1 /*------------------------------------------------------------------------- 2 * 3 * pathnodes.h 4 * Definitions for planner's internal data structures, especially Paths. 5 * 6 * 7 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group 8 * Portions Copyright (c) 1994, Regents of the University of California 9 * 10 * src/include/nodes/pathnodes.h 11 * 12 *------------------------------------------------------------------------- 13 */ 14 #ifndef PATHNODES_H 15 #define PATHNODES_H 16 17 #include "access/sdir.h" 18 #include "lib/stringinfo.h" 19 #include "nodes/params.h" 20 #include "nodes/parsenodes.h" 21 #include "storage/block.h" 22 23 24 /* 25 * Relids 26 * Set of relation identifiers (indexes into the rangetable). 27 */ 28 typedef Bitmapset *Relids; 29 30 /* 31 * When looking for a "cheapest path", this enum specifies whether we want 32 * cheapest startup cost or cheapest total cost. 33 */ 34 typedef enum CostSelector 35 { 36 STARTUP_COST, TOTAL_COST 37 } CostSelector; 38 39 /* 40 * The cost estimate produced by cost_qual_eval() includes both a one-time 41 * (startup) cost, and a per-tuple cost. 42 */ 43 typedef struct QualCost 44 { 45 Cost startup; /* one-time cost */ 46 Cost per_tuple; /* per-evaluation cost */ 47 } QualCost; 48 49 /* 50 * Costing aggregate function execution requires these statistics about 51 * the aggregates to be executed by a given Agg node. Note that the costs 52 * include the execution costs of the aggregates' argument expressions as 53 * well as the aggregate functions themselves. Also, the fields must be 54 * defined so that initializing the struct to zeroes with memset is correct. 55 */ 56 typedef struct AggClauseCosts 57 { 58 int numAggs; /* total number of aggregate functions */ 59 int numOrderedAggs; /* number w/ DISTINCT/ORDER BY/WITHIN GROUP */ 60 bool hasNonPartial; /* does any agg not support partial mode? */ 61 bool hasNonSerial; /* is any partial agg non-serializable? */ 62 QualCost transCost; /* total per-input-row execution costs */ 63 QualCost finalCost; /* total per-aggregated-row costs */ 64 Size transitionSpace; /* space for pass-by-ref transition data */ 65 } AggClauseCosts; 66 67 /* 68 * This enum identifies the different types of "upper" (post-scan/join) 69 * relations that we might deal with during planning. 70 */ 71 typedef enum UpperRelationKind 72 { 73 UPPERREL_SETOP, /* result of UNION/INTERSECT/EXCEPT, if any */ 74 UPPERREL_PARTIAL_GROUP_AGG, /* result of partial grouping/aggregation, if 75 * any */ 76 UPPERREL_GROUP_AGG, /* result of grouping/aggregation, if any */ 77 UPPERREL_WINDOW, /* result of window functions, if any */ 78 UPPERREL_DISTINCT, /* result of "SELECT DISTINCT", if any */ 79 UPPERREL_ORDERED, /* result of ORDER BY, if any */ 80 UPPERREL_FINAL /* result of any remaining top-level actions */ 81 /* NB: UPPERREL_FINAL must be last enum entry; it's used to size arrays */ 82 } UpperRelationKind; 83 84 /* 85 * This enum identifies which type of relation is being planned through the 86 * inheritance planner. INHKIND_NONE indicates the inheritance planner 87 * was not used. 88 */ 89 typedef enum InheritanceKind 90 { 91 INHKIND_NONE, 92 INHKIND_INHERITED, 93 INHKIND_PARTITIONED 94 } InheritanceKind; 95 96 /*---------- 97 * PlannerGlobal 98 * Global information for planning/optimization 99 * 100 * PlannerGlobal holds state for an entire planner invocation; this state 101 * is shared across all levels of sub-Queries that exist in the command being 102 * planned. 103 *---------- 104 */ 105 typedef struct PlannerGlobal 106 { 107 NodeTag type; 108 109 ParamListInfo boundParams; /* Param values provided to planner() */ 110 111 List *subplans; /* Plans for SubPlan nodes */ 112 113 List *subroots; /* PlannerInfos for SubPlan nodes */ 114 115 Bitmapset *rewindPlanIDs; /* indices of subplans that require REWIND */ 116 117 List *finalrtable; /* "flat" rangetable for executor */ 118 119 List *finalrowmarks; /* "flat" list of PlanRowMarks */ 120 121 List *resultRelations; /* "flat" list of integer RT indexes */ 122 123 List *rootResultRelations; /* "flat" list of integer RT indexes */ 124 125 List *appendRelations; /* "flat" list of AppendRelInfos */ 126 127 List *relationOids; /* OIDs of relations the plan depends on */ 128 129 List *invalItems; /* other dependencies, as PlanInvalItems */ 130 131 List *paramExecTypes; /* type OIDs for PARAM_EXEC Params */ 132 133 Index lastPHId; /* highest PlaceHolderVar ID assigned */ 134 135 Index lastRowMarkId; /* highest PlanRowMark ID assigned */ 136 137 int lastPlanNodeId; /* highest plan node ID assigned */ 138 139 bool transientPlan; /* redo plan when TransactionXmin changes? */ 140 141 bool dependsOnRole; /* is plan specific to current role? */ 142 143 bool parallelModeOK; /* parallel mode potentially OK? */ 144 145 bool parallelModeNeeded; /* parallel mode actually required? */ 146 147 char maxParallelHazard; /* worst PROPARALLEL hazard level */ 148 149 PartitionDirectory partition_directory; /* partition descriptors */ 150 } PlannerGlobal; 151 152 /* macro for fetching the Plan associated with a SubPlan node */ 153 #define planner_subplan_get_plan(root, subplan) \ 154 ((Plan *) list_nth((root)->glob->subplans, (subplan)->plan_id - 1)) 155 156 157 /*---------- 158 * PlannerInfo 159 * Per-query information for planning/optimization 160 * 161 * This struct is conventionally called "root" in all the planner routines. 162 * It holds links to all of the planner's working state, in addition to the 163 * original Query. Note that at present the planner extensively modifies 164 * the passed-in Query data structure; someday that should stop. 165 * 166 * For reasons explained in optimizer/optimizer.h, we define the typedef 167 * either here or in that header, whichever is read first. 168 *---------- 169 */ 170 #ifndef HAVE_PLANNERINFO_TYPEDEF 171 typedef struct PlannerInfo PlannerInfo; 172 #define HAVE_PLANNERINFO_TYPEDEF 1 173 #endif 174 175 struct PlannerInfo 176 { 177 NodeTag type; 178 179 Query *parse; /* the Query being planned */ 180 181 PlannerGlobal *glob; /* global info for current planner run */ 182 183 Index query_level; /* 1 at the outermost Query */ 184 185 PlannerInfo *parent_root; /* NULL at outermost Query */ 186 187 /* 188 * plan_params contains the expressions that this query level needs to 189 * make available to a lower query level that is currently being planned. 190 * outer_params contains the paramIds of PARAM_EXEC Params that outer 191 * query levels will make available to this query level. 192 */ 193 List *plan_params; /* list of PlannerParamItems, see below */ 194 Bitmapset *outer_params; 195 196 /* 197 * simple_rel_array holds pointers to "base rels" and "other rels" (see 198 * comments for RelOptInfo for more info). It is indexed by rangetable 199 * index (so entry 0 is always wasted). Entries can be NULL when an RTE 200 * does not correspond to a base relation, such as a join RTE or an 201 * unreferenced view RTE; or if the RelOptInfo hasn't been made yet. 202 */ 203 struct RelOptInfo **simple_rel_array; /* All 1-rel RelOptInfos */ 204 int simple_rel_array_size; /* allocated size of array */ 205 206 /* 207 * simple_rte_array is the same length as simple_rel_array and holds 208 * pointers to the associated rangetable entries. Using this is a shade 209 * faster than using rt_fetch(), mostly due to fewer indirections. 210 */ 211 RangeTblEntry **simple_rte_array; /* rangetable as an array */ 212 213 /* 214 * append_rel_array is the same length as the above arrays, and holds 215 * pointers to the corresponding AppendRelInfo entry indexed by 216 * child_relid, or NULL if the rel is not an appendrel child. The array 217 * itself is not allocated if append_rel_list is empty. 218 */ 219 struct AppendRelInfo **append_rel_array; 220 221 /* 222 * all_baserels is a Relids set of all base relids (but not "other" 223 * relids) in the query; that is, the Relids identifier of the final join 224 * we need to form. This is computed in make_one_rel, just before we 225 * start making Paths. 226 */ 227 Relids all_baserels; 228 229 /* 230 * nullable_baserels is a Relids set of base relids that are nullable by 231 * some outer join in the jointree; these are rels that are potentially 232 * nullable below the WHERE clause, SELECT targetlist, etc. This is 233 * computed in deconstruct_jointree. 234 */ 235 Relids nullable_baserels; 236 237 /* 238 * join_rel_list is a list of all join-relation RelOptInfos we have 239 * considered in this planning run. For small problems we just scan the 240 * list to do lookups, but when there are many join relations we build a 241 * hash table for faster lookups. The hash table is present and valid 242 * when join_rel_hash is not NULL. Note that we still maintain the list 243 * even when using the hash table for lookups; this simplifies life for 244 * GEQO. 245 */ 246 List *join_rel_list; /* list of join-relation RelOptInfos */ 247 struct HTAB *join_rel_hash; /* optional hashtable for join relations */ 248 249 /* 250 * When doing a dynamic-programming-style join search, join_rel_level[k] 251 * is a list of all join-relation RelOptInfos of level k, and 252 * join_cur_level is the current level. New join-relation RelOptInfos are 253 * automatically added to the join_rel_level[join_cur_level] list. 254 * join_rel_level is NULL if not in use. 255 */ 256 List **join_rel_level; /* lists of join-relation RelOptInfos */ 257 int join_cur_level; /* index of list being extended */ 258 259 List *init_plans; /* init SubPlans for query */ 260 261 List *cte_plan_ids; /* per-CTE-item list of subplan IDs */ 262 263 List *multiexpr_params; /* List of Lists of Params for MULTIEXPR 264 * subquery outputs */ 265 266 List *eq_classes; /* list of active EquivalenceClasses */ 267 268 bool ec_merging_done; /* set true once ECs are canonical */ 269 270 List *canon_pathkeys; /* list of "canonical" PathKeys */ 271 272 List *left_join_clauses; /* list of RestrictInfos for mergejoinable 273 * outer join clauses w/nonnullable var on 274 * left */ 275 276 List *right_join_clauses; /* list of RestrictInfos for mergejoinable 277 * outer join clauses w/nonnullable var on 278 * right */ 279 280 List *full_join_clauses; /* list of RestrictInfos for mergejoinable 281 * full join clauses */ 282 283 List *join_info_list; /* list of SpecialJoinInfos */ 284 285 /* 286 * Note: for AppendRelInfos describing partitions of a partitioned table, 287 * we guarantee that partitions that come earlier in the partitioned 288 * table's PartitionDesc will appear earlier in append_rel_list. 289 */ 290 List *append_rel_list; /* list of AppendRelInfos */ 291 292 List *rowMarks; /* list of PlanRowMarks */ 293 294 List *placeholder_list; /* list of PlaceHolderInfos */ 295 296 List *fkey_list; /* list of ForeignKeyOptInfos */ 297 298 List *query_pathkeys; /* desired pathkeys for query_planner() */ 299 300 List *group_pathkeys; /* groupClause pathkeys, if any */ 301 List *window_pathkeys; /* pathkeys of bottom window, if any */ 302 List *distinct_pathkeys; /* distinctClause pathkeys, if any */ 303 List *sort_pathkeys; /* sortClause pathkeys, if any */ 304 305 List *part_schemes; /* Canonicalised partition schemes used in the 306 * query. */ 307 308 List *initial_rels; /* RelOptInfos we are now trying to join */ 309 310 /* Use fetch_upper_rel() to get any particular upper rel */ 311 List *upper_rels[UPPERREL_FINAL + 1]; /* upper-rel RelOptInfos */ 312 313 /* Result tlists chosen by grouping_planner for upper-stage processing */ 314 struct PathTarget *upper_targets[UPPERREL_FINAL + 1]; 315 316 /* 317 * The fully-processed targetlist is kept here. It differs from 318 * parse->targetList in that (for INSERT and UPDATE) it's been reordered 319 * to match the target table, and defaults have been filled in. Also, 320 * additional resjunk targets may be present. preprocess_targetlist() 321 * does most of this work, but note that more resjunk targets can get 322 * added during appendrel expansion. (Hence, upper_targets mustn't get 323 * set up till after that.) 324 */ 325 List *processed_tlist; 326 327 /* Fields filled during create_plan() for use in setrefs.c */ 328 AttrNumber *grouping_map; /* for GroupingFunc fixup */ 329 List *minmax_aggs; /* List of MinMaxAggInfos */ 330 331 MemoryContext planner_cxt; /* context holding PlannerInfo */ 332 333 double total_table_pages; /* # of pages in all non-dummy tables of 334 * query */ 335 336 double tuple_fraction; /* tuple_fraction passed to query_planner */ 337 double limit_tuples; /* limit_tuples passed to query_planner */ 338 339 Index qual_security_level; /* minimum security_level for quals */ 340 /* Note: qual_security_level is zero if there are no securityQuals */ 341 342 InheritanceKind inhTargetKind; /* indicates if the target relation is an 343 * inheritance child or partition or a 344 * partitioned table */ 345 bool hasJoinRTEs; /* true if any RTEs are RTE_JOIN kind */ 346 bool hasLateralRTEs; /* true if any RTEs are marked LATERAL */ 347 bool hasHavingQual; /* true if havingQual was non-null */ 348 bool hasPseudoConstantQuals; /* true if any RestrictInfo has 349 * pseudoconstant = true */ 350 bool hasRecursion; /* true if planning a recursive WITH item */ 351 352 /* These fields are used only when hasRecursion is true: */ 353 int wt_param_id; /* PARAM_EXEC ID for the work table */ 354 struct Path *non_recursive_path; /* a path for non-recursive term */ 355 356 /* These fields are workspace for createplan.c */ 357 Relids curOuterRels; /* outer rels above current node */ 358 List *curOuterParams; /* not-yet-assigned NestLoopParams */ 359 360 /* optional private data for join_search_hook, e.g., GEQO */ 361 void *join_search_private; 362 363 /* Does this query modify any partition key columns? */ 364 bool partColsUpdated; 365 }; 366 367 368 /* 369 * In places where it's known that simple_rte_array[] must have been prepared 370 * already, we just index into it to fetch RTEs. In code that might be 371 * executed before or after entering query_planner(), use this macro. 372 */ 373 #define planner_rt_fetch(rti, root) \ 374 ((root)->simple_rte_array ? (root)->simple_rte_array[rti] : \ 375 rt_fetch(rti, (root)->parse->rtable)) 376 377 /* 378 * If multiple relations are partitioned the same way, all such partitions 379 * will have a pointer to the same PartitionScheme. A list of PartitionScheme 380 * objects is attached to the PlannerInfo. By design, the partition scheme 381 * incorporates only the general properties of the partition method (LIST vs. 382 * RANGE, number of partitioning columns and the type information for each) 383 * and not the specific bounds. 384 * 385 * We store the opclass-declared input data types instead of the partition key 386 * datatypes since the former rather than the latter are used to compare 387 * partition bounds. Since partition key data types and the opclass declared 388 * input data types are expected to be binary compatible (per ResolveOpClass), 389 * both of those should have same byval and length properties. 390 */ 391 typedef struct PartitionSchemeData 392 { 393 char strategy; /* partition strategy */ 394 int16 partnatts; /* number of partition attributes */ 395 Oid *partopfamily; /* OIDs of operator families */ 396 Oid *partopcintype; /* OIDs of opclass declared input data types */ 397 Oid *partcollation; /* OIDs of partitioning collations */ 398 399 /* Cached information about partition key data types. */ 400 int16 *parttyplen; 401 bool *parttypbyval; 402 403 /* Cached information about partition comparison functions. */ 404 struct FmgrInfo *partsupfunc; 405 } PartitionSchemeData; 406 407 typedef struct PartitionSchemeData *PartitionScheme; 408 409 /*---------- 410 * RelOptInfo 411 * Per-relation information for planning/optimization 412 * 413 * For planning purposes, a "base rel" is either a plain relation (a table) 414 * or the output of a sub-SELECT or function that appears in the range table. 415 * In either case it is uniquely identified by an RT index. A "joinrel" 416 * is the joining of two or more base rels. A joinrel is identified by 417 * the set of RT indexes for its component baserels. We create RelOptInfo 418 * nodes for each baserel and joinrel, and store them in the PlannerInfo's 419 * simple_rel_array and join_rel_list respectively. 420 * 421 * Note that there is only one joinrel for any given set of component 422 * baserels, no matter what order we assemble them in; so an unordered 423 * set is the right datatype to identify it with. 424 * 425 * We also have "other rels", which are like base rels in that they refer to 426 * single RT indexes; but they are not part of the join tree, and are given 427 * a different RelOptKind to identify them. 428 * Currently the only kind of otherrels are those made for member relations 429 * of an "append relation", that is an inheritance set or UNION ALL subquery. 430 * An append relation has a parent RTE that is a base rel, which represents 431 * the entire append relation. The member RTEs are otherrels. The parent 432 * is present in the query join tree but the members are not. The member 433 * RTEs and otherrels are used to plan the scans of the individual tables or 434 * subqueries of the append set; then the parent baserel is given Append 435 * and/or MergeAppend paths comprising the best paths for the individual 436 * member rels. (See comments for AppendRelInfo for more information.) 437 * 438 * At one time we also made otherrels to represent join RTEs, for use in 439 * handling join alias Vars. Currently this is not needed because all join 440 * alias Vars are expanded to non-aliased form during preprocess_expression. 441 * 442 * We also have relations representing joins between child relations of 443 * different partitioned tables. These relations are not added to 444 * join_rel_level lists as they are not joined directly by the dynamic 445 * programming algorithm. 446 * 447 * There is also a RelOptKind for "upper" relations, which are RelOptInfos 448 * that describe post-scan/join processing steps, such as aggregation. 449 * Many of the fields in these RelOptInfos are meaningless, but their Path 450 * fields always hold Paths showing ways to do that processing step. 451 * 452 * Lastly, there is a RelOptKind for "dead" relations, which are base rels 453 * that we have proven we don't need to join after all. 454 * 455 * Parts of this data structure are specific to various scan and join 456 * mechanisms. It didn't seem worth creating new node types for them. 457 * 458 * relids - Set of base-relation identifiers; it is a base relation 459 * if there is just one, a join relation if more than one 460 * rows - estimated number of tuples in the relation after restriction 461 * clauses have been applied (ie, output rows of a plan for it) 462 * consider_startup - true if there is any value in keeping plain paths for 463 * this rel on the basis of having cheap startup cost 464 * consider_param_startup - the same for parameterized paths 465 * reltarget - Default Path output tlist for this rel; normally contains 466 * Var and PlaceHolderVar nodes for the values we need to 467 * output from this relation. 468 * List is in no particular order, but all rels of an 469 * appendrel set must use corresponding orders. 470 * NOTE: in an appendrel child relation, may contain 471 * arbitrary expressions pulled up from a subquery! 472 * pathlist - List of Path nodes, one for each potentially useful 473 * method of generating the relation 474 * ppilist - ParamPathInfo nodes for parameterized Paths, if any 475 * cheapest_startup_path - the pathlist member with lowest startup cost 476 * (regardless of ordering) among the unparameterized paths; 477 * or NULL if there is no unparameterized path 478 * cheapest_total_path - the pathlist member with lowest total cost 479 * (regardless of ordering) among the unparameterized paths; 480 * or if there is no unparameterized path, the path with lowest 481 * total cost among the paths with minimum parameterization 482 * cheapest_unique_path - for caching cheapest path to produce unique 483 * (no duplicates) output from relation; NULL if not yet requested 484 * cheapest_parameterized_paths - best paths for their parameterizations; 485 * always includes cheapest_total_path, even if that's unparameterized 486 * direct_lateral_relids - rels this rel has direct LATERAL references to 487 * lateral_relids - required outer rels for LATERAL, as a Relids set 488 * (includes both direct and indirect lateral references) 489 * 490 * If the relation is a base relation it will have these fields set: 491 * 492 * relid - RTE index (this is redundant with the relids field, but 493 * is provided for convenience of access) 494 * rtekind - copy of RTE's rtekind field 495 * min_attr, max_attr - range of valid AttrNumbers for rel 496 * attr_needed - array of bitmapsets indicating the highest joinrel 497 * in which each attribute is needed; if bit 0 is set then 498 * the attribute is needed as part of final targetlist 499 * attr_widths - cache space for per-attribute width estimates; 500 * zero means not computed yet 501 * lateral_vars - lateral cross-references of rel, if any (list of 502 * Vars and PlaceHolderVars) 503 * lateral_referencers - relids of rels that reference this one laterally 504 * (includes both direct and indirect lateral references) 505 * indexlist - list of IndexOptInfo nodes for relation's indexes 506 * (always NIL if it's not a table) 507 * pages - number of disk pages in relation (zero if not a table) 508 * tuples - number of tuples in relation (not considering restrictions) 509 * allvisfrac - fraction of disk pages that are marked all-visible 510 * eclass_indexes - EquivalenceClasses that mention this rel (filled 511 * only after EC merging is complete) 512 * subroot - PlannerInfo for subquery (NULL if it's not a subquery) 513 * subplan_params - list of PlannerParamItems to be passed to subquery 514 * 515 * Note: for a subquery, tuples and subroot are not set immediately 516 * upon creation of the RelOptInfo object; they are filled in when 517 * set_subquery_pathlist processes the object. 518 * 519 * For otherrels that are appendrel members, these fields are filled 520 * in just as for a baserel, except we don't bother with lateral_vars. 521 * 522 * If the relation is either a foreign table or a join of foreign tables that 523 * all belong to the same foreign server and are assigned to the same user to 524 * check access permissions as (cf checkAsUser), these fields will be set: 525 * 526 * serverid - OID of foreign server, if foreign table (else InvalidOid) 527 * userid - OID of user to check access as (InvalidOid means current user) 528 * useridiscurrent - we've assumed that userid equals current user 529 * fdwroutine - function hooks for FDW, if foreign table (else NULL) 530 * fdw_private - private state for FDW, if foreign table (else NULL) 531 * 532 * Two fields are used to cache knowledge acquired during the join search 533 * about whether this rel is provably unique when being joined to given other 534 * relation(s), ie, it can have at most one row matching any given row from 535 * that join relation. Currently we only attempt such proofs, and thus only 536 * populate these fields, for base rels; but someday they might be used for 537 * join rels too: 538 * 539 * unique_for_rels - list of Relid sets, each one being a set of other 540 * rels for which this one has been proven unique 541 * non_unique_for_rels - list of Relid sets, each one being a set of 542 * other rels for which we have tried and failed to prove 543 * this one unique 544 * 545 * The presence of the following fields depends on the restrictions 546 * and joins that the relation participates in: 547 * 548 * baserestrictinfo - List of RestrictInfo nodes, containing info about 549 * each non-join qualification clause in which this relation 550 * participates (only used for base rels) 551 * baserestrictcost - Estimated cost of evaluating the baserestrictinfo 552 * clauses at a single tuple (only used for base rels) 553 * baserestrict_min_security - Smallest security_level found among 554 * clauses in baserestrictinfo 555 * joininfo - List of RestrictInfo nodes, containing info about each 556 * join clause in which this relation participates (but 557 * note this excludes clauses that might be derivable from 558 * EquivalenceClasses) 559 * has_eclass_joins - flag that EquivalenceClass joins are possible 560 * 561 * Note: Keeping a restrictinfo list in the RelOptInfo is useful only for 562 * base rels, because for a join rel the set of clauses that are treated as 563 * restrict clauses varies depending on which sub-relations we choose to join. 564 * (For example, in a 3-base-rel join, a clause relating rels 1 and 2 must be 565 * treated as a restrictclause if we join {1} and {2 3} to make {1 2 3}; but 566 * if we join {1 2} and {3} then that clause will be a restrictclause in {1 2} 567 * and should not be processed again at the level of {1 2 3}.) Therefore, 568 * the restrictinfo list in the join case appears in individual JoinPaths 569 * (field joinrestrictinfo), not in the parent relation. But it's OK for 570 * the RelOptInfo to store the joininfo list, because that is the same 571 * for a given rel no matter how we form it. 572 * 573 * We store baserestrictcost in the RelOptInfo (for base relations) because 574 * we know we will need it at least once (to price the sequential scan) 575 * and may need it multiple times to price index scans. 576 * 577 * A join relation is considered to be partitioned if it is formed from a 578 * join of two relations that are partitioned, have matching partitioning 579 * schemes, and are joined on an equijoin of the partitioning columns. 580 * Under those conditions we can consider the join relation to be partitioned 581 * by either relation's partitioning keys, though some care is needed if 582 * either relation can be forced to null by outer-joining. For example, an 583 * outer join like (A LEFT JOIN B ON A.a = B.b) may produce rows with B.b 584 * NULL. These rows may not fit the partitioning conditions imposed on B. 585 * Hence, strictly speaking, the join is not partitioned by B.b and thus 586 * partition keys of an outer join should include partition key expressions 587 * from the non-nullable side only. However, if a subsequent join uses 588 * strict comparison operators (and all commonly-used equijoin operators are 589 * strict), the presence of nulls doesn't cause a problem: such rows couldn't 590 * match anything on the other side and thus they don't create a need to do 591 * any cross-partition sub-joins. Hence we can treat such values as still 592 * partitioning the join output for the purpose of additional partitionwise 593 * joining, so long as a strict join operator is used by the next join. 594 * 595 * If the relation is partitioned, these fields will be set: 596 * 597 * part_scheme - Partitioning scheme of the relation 598 * nparts - Number of partitions 599 * boundinfo - Partition bounds 600 * partbounds_merged - true if partition bounds are merged ones 601 * partition_qual - Partition constraint if not the root 602 * part_rels - RelOptInfos for each partition 603 * all_partrels - Relids set of all partition relids 604 * partexprs, nullable_partexprs - Partition key expressions 605 * partitioned_child_rels - RT indexes of unpruned partitions of 606 * this relation that are partitioned tables 607 * themselves, in hierarchical order 608 * 609 * The partexprs and nullable_partexprs arrays each contain 610 * part_scheme->partnatts elements. Each of the elements is a list of 611 * partition key expressions. For partitioned base relations, there is one 612 * expression in each partexprs element, and nullable_partexprs is empty. 613 * For partitioned join relations, each base relation within the join 614 * contributes one partition key expression per partitioning column; 615 * that expression goes in the partexprs[i] list if the base relation 616 * is not nullable by this join or any lower outer join, or in the 617 * nullable_partexprs[i] list if the base relation is nullable. 618 * Furthermore, FULL JOINs add extra nullable_partexprs expressions 619 * corresponding to COALESCE expressions of the left and right join columns, 620 * to simplify matching join clauses to those lists. 621 *---------- 622 */ 623 typedef enum RelOptKind 624 { 625 RELOPT_BASEREL, 626 RELOPT_JOINREL, 627 RELOPT_OTHER_MEMBER_REL, 628 RELOPT_OTHER_JOINREL, 629 RELOPT_UPPER_REL, 630 RELOPT_OTHER_UPPER_REL, 631 RELOPT_DEADREL 632 } RelOptKind; 633 634 /* 635 * Is the given relation a simple relation i.e a base or "other" member 636 * relation? 637 */ 638 #define IS_SIMPLE_REL(rel) \ 639 ((rel)->reloptkind == RELOPT_BASEREL || \ 640 (rel)->reloptkind == RELOPT_OTHER_MEMBER_REL) 641 642 /* Is the given relation a join relation? */ 643 #define IS_JOIN_REL(rel) \ 644 ((rel)->reloptkind == RELOPT_JOINREL || \ 645 (rel)->reloptkind == RELOPT_OTHER_JOINREL) 646 647 /* Is the given relation an upper relation? */ 648 #define IS_UPPER_REL(rel) \ 649 ((rel)->reloptkind == RELOPT_UPPER_REL || \ 650 (rel)->reloptkind == RELOPT_OTHER_UPPER_REL) 651 652 /* Is the given relation an "other" relation? */ 653 #define IS_OTHER_REL(rel) \ 654 ((rel)->reloptkind == RELOPT_OTHER_MEMBER_REL || \ 655 (rel)->reloptkind == RELOPT_OTHER_JOINREL || \ 656 (rel)->reloptkind == RELOPT_OTHER_UPPER_REL) 657 658 typedef struct RelOptInfo 659 { 660 NodeTag type; 661 662 RelOptKind reloptkind; 663 664 /* all relations included in this RelOptInfo */ 665 Relids relids; /* set of base relids (rangetable indexes) */ 666 667 /* size estimates generated by planner */ 668 double rows; /* estimated number of result tuples */ 669 670 /* per-relation planner control flags */ 671 bool consider_startup; /* keep cheap-startup-cost paths? */ 672 bool consider_param_startup; /* ditto, for parameterized paths? */ 673 bool consider_parallel; /* consider parallel paths? */ 674 675 /* default result targetlist for Paths scanning this relation */ 676 struct PathTarget *reltarget; /* list of Vars/Exprs, cost, width */ 677 678 /* materialization information */ 679 List *pathlist; /* Path structures */ 680 List *ppilist; /* ParamPathInfos used in pathlist */ 681 List *partial_pathlist; /* partial Paths */ 682 struct Path *cheapest_startup_path; 683 struct Path *cheapest_total_path; 684 struct Path *cheapest_unique_path; 685 List *cheapest_parameterized_paths; 686 687 /* parameterization information needed for both base rels and join rels */ 688 /* (see also lateral_vars and lateral_referencers) */ 689 Relids direct_lateral_relids; /* rels directly laterally referenced */ 690 Relids lateral_relids; /* minimum parameterization of rel */ 691 692 /* information about a base rel (not set for join rels!) */ 693 Index relid; 694 Oid reltablespace; /* containing tablespace */ 695 RTEKind rtekind; /* RELATION, SUBQUERY, FUNCTION, etc */ 696 AttrNumber min_attr; /* smallest attrno of rel (often <0) */ 697 AttrNumber max_attr; /* largest attrno of rel */ 698 Relids *attr_needed; /* array indexed [min_attr .. max_attr] */ 699 int32 *attr_widths; /* array indexed [min_attr .. max_attr] */ 700 List *lateral_vars; /* LATERAL Vars and PHVs referenced by rel */ 701 Relids lateral_referencers; /* rels that reference me laterally */ 702 List *indexlist; /* list of IndexOptInfo */ 703 List *statlist; /* list of StatisticExtInfo */ 704 BlockNumber pages; /* size estimates derived from pg_class */ 705 double tuples; 706 double allvisfrac; 707 Bitmapset *eclass_indexes; /* Indexes in PlannerInfo's eq_classes list of 708 * ECs that mention this rel */ 709 PlannerInfo *subroot; /* if subquery */ 710 List *subplan_params; /* if subquery */ 711 int rel_parallel_workers; /* wanted number of parallel workers */ 712 713 /* Information about foreign tables and foreign joins */ 714 Oid serverid; /* identifies server for the table or join */ 715 Oid userid; /* identifies user to check access as */ 716 bool useridiscurrent; /* join is only valid for current user */ 717 /* use "struct FdwRoutine" to avoid including fdwapi.h here */ 718 struct FdwRoutine *fdwroutine; 719 void *fdw_private; 720 721 /* cache space for remembering if we have proven this relation unique */ 722 List *unique_for_rels; /* known unique for these other relid 723 * set(s) */ 724 List *non_unique_for_rels; /* known not unique for these set(s) */ 725 726 /* used by various scans and joins: */ 727 List *baserestrictinfo; /* RestrictInfo structures (if base rel) */ 728 QualCost baserestrictcost; /* cost of evaluating the above */ 729 Index baserestrict_min_security; /* min security_level found in 730 * baserestrictinfo */ 731 List *joininfo; /* RestrictInfo structures for join clauses 732 * involving this rel */ 733 bool has_eclass_joins; /* T means joininfo is incomplete */ 734 735 /* used by partitionwise joins: */ 736 bool consider_partitionwise_join; /* consider partitionwise join 737 * paths? (if partitioned rel) */ 738 Relids top_parent_relids; /* Relids of topmost parents (if "other" 739 * rel) */ 740 741 /* used for partitioned relations: */ 742 PartitionScheme part_scheme; /* Partitioning scheme */ 743 int nparts; /* Number of partitions; -1 if not yet set; in 744 * case of a join relation 0 means it's 745 * considered unpartitioned */ 746 struct PartitionBoundInfoData *boundinfo; /* Partition bounds */ 747 bool partbounds_merged; /* True if partition bounds were created 748 * by partition_bounds_merge() */ 749 List *partition_qual; /* Partition constraint, if not the root */ 750 struct RelOptInfo **part_rels; /* Array of RelOptInfos of partitions, 751 * stored in the same order as bounds */ 752 Relids all_partrels; /* Relids set of all partition relids */ 753 List **partexprs; /* Non-nullable partition key expressions */ 754 List **nullable_partexprs; /* Nullable partition key expressions */ 755 List *partitioned_child_rels; /* List of RT indexes */ 756 } RelOptInfo; 757 758 /* 759 * Is given relation partitioned? 760 * 761 * It's not enough to test whether rel->part_scheme is set, because it might 762 * be that the basic partitioning properties of the input relations matched 763 * but the partition bounds did not. Also, if we are able to prove a rel 764 * dummy (empty), we should henceforth treat it as unpartitioned. 765 */ 766 #define IS_PARTITIONED_REL(rel) \ 767 ((rel)->part_scheme && (rel)->boundinfo && (rel)->nparts > 0 && \ 768 (rel)->part_rels && !IS_DUMMY_REL(rel)) 769 770 /* 771 * Convenience macro to make sure that a partitioned relation has all the 772 * required members set. 773 */ 774 #define REL_HAS_ALL_PART_PROPS(rel) \ 775 ((rel)->part_scheme && (rel)->boundinfo && (rel)->nparts > 0 && \ 776 (rel)->part_rels && (rel)->partexprs && (rel)->nullable_partexprs) 777 778 /* 779 * IndexOptInfo 780 * Per-index information for planning/optimization 781 * 782 * indexkeys[], indexcollations[] each have ncolumns entries. 783 * opfamily[], and opcintype[] each have nkeycolumns entries. They do 784 * not contain any information about included attributes. 785 * 786 * sortopfamily[], reverse_sort[], and nulls_first[] have 787 * nkeycolumns entries, if the index is ordered; but if it is unordered, 788 * those pointers are NULL. 789 * 790 * Zeroes in the indexkeys[] array indicate index columns that are 791 * expressions; there is one element in indexprs for each such column. 792 * 793 * For an ordered index, reverse_sort[] and nulls_first[] describe the 794 * sort ordering of a forward indexscan; we can also consider a backward 795 * indexscan, which will generate the reverse ordering. 796 * 797 * The indexprs and indpred expressions have been run through 798 * prepqual.c and eval_const_expressions() for ease of matching to 799 * WHERE clauses. indpred is in implicit-AND form. 800 * 801 * indextlist is a TargetEntry list representing the index columns. 802 * It provides an equivalent base-relation Var for each simple column, 803 * and links to the matching indexprs element for each expression column. 804 * 805 * While most of these fields are filled when the IndexOptInfo is created 806 * (by plancat.c), indrestrictinfo and predOK are set later, in 807 * check_index_predicates(). 808 */ 809 #ifndef HAVE_INDEXOPTINFO_TYPEDEF 810 typedef struct IndexOptInfo IndexOptInfo; 811 #define HAVE_INDEXOPTINFO_TYPEDEF 1 812 #endif 813 814 struct IndexOptInfo 815 { 816 NodeTag type; 817 818 Oid indexoid; /* OID of the index relation */ 819 Oid reltablespace; /* tablespace of index (not table) */ 820 RelOptInfo *rel; /* back-link to index's table */ 821 822 /* index-size statistics (from pg_class and elsewhere) */ 823 BlockNumber pages; /* number of disk pages in index */ 824 double tuples; /* number of index tuples in index */ 825 int tree_height; /* index tree height, or -1 if unknown */ 826 827 /* index descriptor information */ 828 int ncolumns; /* number of columns in index */ 829 int nkeycolumns; /* number of key columns in index */ 830 int *indexkeys; /* column numbers of index's attributes both 831 * key and included columns, or 0 */ 832 Oid *indexcollations; /* OIDs of collations of index columns */ 833 Oid *opfamily; /* OIDs of operator families for columns */ 834 Oid *opcintype; /* OIDs of opclass declared input data types */ 835 Oid *sortopfamily; /* OIDs of btree opfamilies, if orderable */ 836 bool *reverse_sort; /* is sort order descending? */ 837 bool *nulls_first; /* do NULLs come first in the sort order? */ 838 bytea **opclassoptions; /* opclass-specific options for columns */ 839 bool *canreturn; /* which index cols can be returned in an 840 * index-only scan? */ 841 Oid relam; /* OID of the access method (in pg_am) */ 842 843 List *indexprs; /* expressions for non-simple index columns */ 844 List *indpred; /* predicate if a partial index, else NIL */ 845 846 List *indextlist; /* targetlist representing index columns */ 847 848 List *indrestrictinfo; /* parent relation's baserestrictinfo 849 * list, less any conditions implied by 850 * the index's predicate (unless it's a 851 * target rel, see comments in 852 * check_index_predicates()) */ 853 854 bool predOK; /* true if index predicate matches query */ 855 bool unique; /* true if a unique index */ 856 bool immediate; /* is uniqueness enforced immediately? */ 857 bool hypothetical; /* true if index doesn't really exist */ 858 859 /* Remaining fields are copied from the index AM's API struct: */ 860 bool amcanorderbyop; /* does AM support order by operator result? */ 861 bool amoptionalkey; /* can query omit key for the first column? */ 862 bool amsearcharray; /* can AM handle ScalarArrayOpExpr quals? */ 863 bool amsearchnulls; /* can AM search for NULL/NOT NULL entries? */ 864 bool amhasgettuple; /* does AM have amgettuple interface? */ 865 bool amhasgetbitmap; /* does AM have amgetbitmap interface? */ 866 bool amcanparallel; /* does AM support parallel scan? */ 867 bool amcanmarkpos; /* does AM support mark/restore? */ 868 /* Rather than include amapi.h here, we declare amcostestimate like this */ 869 void (*amcostestimate) (); /* AM's cost estimator */ 870 }; 871 872 /* 873 * ForeignKeyOptInfo 874 * Per-foreign-key information for planning/optimization 875 * 876 * The per-FK-column arrays can be fixed-size because we allow at most 877 * INDEX_MAX_KEYS columns in a foreign key constraint. Each array has 878 * nkeys valid entries. 879 */ 880 typedef struct ForeignKeyOptInfo 881 { 882 NodeTag type; 883 884 /* Basic data about the foreign key (fetched from catalogs): */ 885 Index con_relid; /* RT index of the referencing table */ 886 Index ref_relid; /* RT index of the referenced table */ 887 int nkeys; /* number of columns in the foreign key */ 888 AttrNumber conkey[INDEX_MAX_KEYS]; /* cols in referencing table */ 889 AttrNumber confkey[INDEX_MAX_KEYS]; /* cols in referenced table */ 890 Oid conpfeqop[INDEX_MAX_KEYS]; /* PK = FK operator OIDs */ 891 892 /* Derived info about whether FK's equality conditions match the query: */ 893 int nmatched_ec; /* # of FK cols matched by ECs */ 894 int nmatched_rcols; /* # of FK cols matched by non-EC rinfos */ 895 int nmatched_ri; /* total # of non-EC rinfos matched to FK */ 896 /* Pointer to eclass matching each column's condition, if there is one */ 897 struct EquivalenceClass *eclass[INDEX_MAX_KEYS]; 898 /* List of non-EC RestrictInfos matching each column's condition */ 899 List *rinfos[INDEX_MAX_KEYS]; 900 } ForeignKeyOptInfo; 901 902 /* 903 * StatisticExtInfo 904 * Information about extended statistics for planning/optimization 905 * 906 * Each pg_statistic_ext row is represented by one or more nodes of this 907 * type, or even zero if ANALYZE has not computed them. 908 */ 909 typedef struct StatisticExtInfo 910 { 911 NodeTag type; 912 913 Oid statOid; /* OID of the statistics row */ 914 RelOptInfo *rel; /* back-link to statistic's table */ 915 char kind; /* statistics kind of this entry */ 916 Bitmapset *keys; /* attnums of the columns covered */ 917 } StatisticExtInfo; 918 919 /* 920 * EquivalenceClasses 921 * 922 * Whenever we can determine that a mergejoinable equality clause A = B is 923 * not delayed by any outer join, we create an EquivalenceClass containing 924 * the expressions A and B to record this knowledge. If we later find another 925 * equivalence B = C, we add C to the existing EquivalenceClass; this may 926 * require merging two existing EquivalenceClasses. At the end of the qual 927 * distribution process, we have sets of values that are known all transitively 928 * equal to each other, where "equal" is according to the rules of the btree 929 * operator family(s) shown in ec_opfamilies, as well as the collation shown 930 * by ec_collation. (We restrict an EC to contain only equalities whose 931 * operators belong to the same set of opfamilies. This could probably be 932 * relaxed, but for now it's not worth the trouble, since nearly all equality 933 * operators belong to only one btree opclass anyway. Similarly, we suppose 934 * that all or none of the input datatypes are collatable, so that a single 935 * collation value is sufficient.) 936 * 937 * We also use EquivalenceClasses as the base structure for PathKeys, letting 938 * us represent knowledge about different sort orderings being equivalent. 939 * Since every PathKey must reference an EquivalenceClass, we will end up 940 * with single-member EquivalenceClasses whenever a sort key expression has 941 * not been equivalenced to anything else. It is also possible that such an 942 * EquivalenceClass will contain a volatile expression ("ORDER BY random()"), 943 * which is a case that can't arise otherwise since clauses containing 944 * volatile functions are never considered mergejoinable. We mark such 945 * EquivalenceClasses specially to prevent them from being merged with 946 * ordinary EquivalenceClasses. Also, for volatile expressions we have 947 * to be careful to match the EquivalenceClass to the correct targetlist 948 * entry: consider SELECT random() AS a, random() AS b ... ORDER BY b,a. 949 * So we record the SortGroupRef of the originating sort clause. 950 * 951 * We allow equality clauses appearing below the nullable side of an outer join 952 * to form EquivalenceClasses, but these have a slightly different meaning: 953 * the included values might be all NULL rather than all the same non-null 954 * values. See src/backend/optimizer/README for more on that point. 955 * 956 * NB: if ec_merged isn't NULL, this class has been merged into another, and 957 * should be ignored in favor of using the pointed-to class. 958 */ 959 typedef struct EquivalenceClass 960 { 961 NodeTag type; 962 963 List *ec_opfamilies; /* btree operator family OIDs */ 964 Oid ec_collation; /* collation, if datatypes are collatable */ 965 List *ec_members; /* list of EquivalenceMembers */ 966 List *ec_sources; /* list of generating RestrictInfos */ 967 List *ec_derives; /* list of derived RestrictInfos */ 968 Relids ec_relids; /* all relids appearing in ec_members, except 969 * for child members (see below) */ 970 bool ec_has_const; /* any pseudoconstants in ec_members? */ 971 bool ec_has_volatile; /* the (sole) member is a volatile expr */ 972 bool ec_below_outer_join; /* equivalence applies below an OJ */ 973 bool ec_broken; /* failed to generate needed clauses? */ 974 Index ec_sortref; /* originating sortclause label, or 0 */ 975 Index ec_min_security; /* minimum security_level in ec_sources */ 976 Index ec_max_security; /* maximum security_level in ec_sources */ 977 struct EquivalenceClass *ec_merged; /* set if merged into another EC */ 978 } EquivalenceClass; 979 980 /* 981 * If an EC contains a const and isn't below-outer-join, any PathKey depending 982 * on it must be redundant, since there's only one possible value of the key. 983 */ 984 #define EC_MUST_BE_REDUNDANT(eclass) \ 985 ((eclass)->ec_has_const && !(eclass)->ec_below_outer_join) 986 987 /* 988 * EquivalenceMember - one member expression of an EquivalenceClass 989 * 990 * em_is_child signifies that this element was built by transposing a member 991 * for an appendrel parent relation to represent the corresponding expression 992 * for an appendrel child. These members are used for determining the 993 * pathkeys of scans on the child relation and for explicitly sorting the 994 * child when necessary to build a MergeAppend path for the whole appendrel 995 * tree. An em_is_child member has no impact on the properties of the EC as a 996 * whole; in particular the EC's ec_relids field does NOT include the child 997 * relation. An em_is_child member should never be marked em_is_const nor 998 * cause ec_has_const or ec_has_volatile to be set, either. Thus, em_is_child 999 * members are not really full-fledged members of the EC, but just reflections 1000 * or doppelgangers of real members. Most operations on EquivalenceClasses 1001 * should ignore em_is_child members, and those that don't should test 1002 * em_relids to make sure they only consider relevant members. 1003 * 1004 * em_datatype is usually the same as exprType(em_expr), but can be 1005 * different when dealing with a binary-compatible opfamily; in particular 1006 * anyarray_ops would never work without this. Use em_datatype when 1007 * looking up a specific btree operator to work with this expression. 1008 */ 1009 typedef struct EquivalenceMember 1010 { 1011 NodeTag type; 1012 1013 Expr *em_expr; /* the expression represented */ 1014 Relids em_relids; /* all relids appearing in em_expr */ 1015 Relids em_nullable_relids; /* nullable by lower outer joins */ 1016 bool em_is_const; /* expression is pseudoconstant? */ 1017 bool em_is_child; /* derived version for a child relation? */ 1018 Oid em_datatype; /* the "nominal type" used by the opfamily */ 1019 } EquivalenceMember; 1020 1021 /* 1022 * PathKeys 1023 * 1024 * The sort ordering of a path is represented by a list of PathKey nodes. 1025 * An empty list implies no known ordering. Otherwise the first item 1026 * represents the primary sort key, the second the first secondary sort key, 1027 * etc. The value being sorted is represented by linking to an 1028 * EquivalenceClass containing that value and including pk_opfamily among its 1029 * ec_opfamilies. The EquivalenceClass tells which collation to use, too. 1030 * This is a convenient method because it makes it trivial to detect 1031 * equivalent and closely-related orderings. (See optimizer/README for more 1032 * information.) 1033 * 1034 * Note: pk_strategy is either BTLessStrategyNumber (for ASC) or 1035 * BTGreaterStrategyNumber (for DESC). We assume that all ordering-capable 1036 * index types will use btree-compatible strategy numbers. 1037 */ 1038 typedef struct PathKey 1039 { 1040 NodeTag type; 1041 1042 EquivalenceClass *pk_eclass; /* the value that is ordered */ 1043 Oid pk_opfamily; /* btree opfamily defining the ordering */ 1044 int pk_strategy; /* sort direction (ASC or DESC) */ 1045 bool pk_nulls_first; /* do NULLs come before normal values? */ 1046 } PathKey; 1047 1048 1049 /* 1050 * PathTarget 1051 * 1052 * This struct contains what we need to know during planning about the 1053 * targetlist (output columns) that a Path will compute. Each RelOptInfo 1054 * includes a default PathTarget, which its individual Paths may simply 1055 * reference. However, in some cases a Path may compute outputs different 1056 * from other Paths, and in that case we make a custom PathTarget for it. 1057 * For example, an indexscan might return index expressions that would 1058 * otherwise need to be explicitly calculated. (Note also that "upper" 1059 * relations generally don't have useful default PathTargets.) 1060 * 1061 * exprs contains bare expressions; they do not have TargetEntry nodes on top, 1062 * though those will appear in finished Plans. 1063 * 1064 * sortgrouprefs[] is an array of the same length as exprs, containing the 1065 * corresponding sort/group refnos, or zeroes for expressions not referenced 1066 * by sort/group clauses. If sortgrouprefs is NULL (which it generally is in 1067 * RelOptInfo.reltarget targets; only upper-level Paths contain this info), 1068 * we have not identified sort/group columns in this tlist. This allows us to 1069 * deal with sort/group refnos when needed with less expense than including 1070 * TargetEntry nodes in the exprs list. 1071 */ 1072 typedef struct PathTarget 1073 { 1074 NodeTag type; 1075 List *exprs; /* list of expressions to be computed */ 1076 Index *sortgrouprefs; /* corresponding sort/group refnos, or 0 */ 1077 QualCost cost; /* cost of evaluating the expressions */ 1078 int width; /* estimated avg width of result tuples */ 1079 } PathTarget; 1080 1081 /* Convenience macro to get a sort/group refno from a PathTarget */ 1082 #define get_pathtarget_sortgroupref(target, colno) \ 1083 ((target)->sortgrouprefs ? (target)->sortgrouprefs[colno] : (Index) 0) 1084 1085 1086 /* 1087 * ParamPathInfo 1088 * 1089 * All parameterized paths for a given relation with given required outer rels 1090 * link to a single ParamPathInfo, which stores common information such as 1091 * the estimated rowcount for this parameterization. We do this partly to 1092 * avoid recalculations, but mostly to ensure that the estimated rowcount 1093 * is in fact the same for every such path. 1094 * 1095 * Note: ppi_clauses is only used in ParamPathInfos for base relation paths; 1096 * in join cases it's NIL because the set of relevant clauses varies depending 1097 * on how the join is formed. The relevant clauses will appear in each 1098 * parameterized join path's joinrestrictinfo list, instead. 1099 */ 1100 typedef struct ParamPathInfo 1101 { 1102 NodeTag type; 1103 1104 Relids ppi_req_outer; /* rels supplying parameters used by path */ 1105 double ppi_rows; /* estimated number of result tuples */ 1106 List *ppi_clauses; /* join clauses available from outer rels */ 1107 } ParamPathInfo; 1108 1109 1110 /* 1111 * Type "Path" is used as-is for sequential-scan paths, as well as some other 1112 * simple plan types that we don't need any extra information in the path for. 1113 * For other path types it is the first component of a larger struct. 1114 * 1115 * "pathtype" is the NodeTag of the Plan node we could build from this Path. 1116 * It is partially redundant with the Path's NodeTag, but allows us to use 1117 * the same Path type for multiple Plan types when there is no need to 1118 * distinguish the Plan type during path processing. 1119 * 1120 * "parent" identifies the relation this Path scans, and "pathtarget" 1121 * describes the precise set of output columns the Path would compute. 1122 * In simple cases all Paths for a given rel share the same targetlist, 1123 * which we represent by having path->pathtarget equal to parent->reltarget. 1124 * 1125 * "param_info", if not NULL, links to a ParamPathInfo that identifies outer 1126 * relation(s) that provide parameter values to each scan of this path. 1127 * That means this path can only be joined to those rels by means of nestloop 1128 * joins with this path on the inside. Also note that a parameterized path 1129 * is responsible for testing all "movable" joinclauses involving this rel 1130 * and the specified outer rel(s). 1131 * 1132 * "rows" is the same as parent->rows in simple paths, but in parameterized 1133 * paths and UniquePaths it can be less than parent->rows, reflecting the 1134 * fact that we've filtered by extra join conditions or removed duplicates. 1135 * 1136 * "pathkeys" is a List of PathKey nodes (see above), describing the sort 1137 * ordering of the path's output rows. 1138 */ 1139 typedef struct Path 1140 { 1141 NodeTag type; 1142 1143 NodeTag pathtype; /* tag identifying scan/join method */ 1144 1145 RelOptInfo *parent; /* the relation this path can build */ 1146 PathTarget *pathtarget; /* list of Vars/Exprs, cost, width */ 1147 1148 ParamPathInfo *param_info; /* parameterization info, or NULL if none */ 1149 1150 bool parallel_aware; /* engage parallel-aware logic? */ 1151 bool parallel_safe; /* OK to use as part of parallel plan? */ 1152 int parallel_workers; /* desired # of workers; 0 = not parallel */ 1153 1154 /* estimated size/costs for path (see costsize.c for more info) */ 1155 double rows; /* estimated number of result tuples */ 1156 Cost startup_cost; /* cost expended before fetching any tuples */ 1157 Cost total_cost; /* total cost (assuming all tuples fetched) */ 1158 1159 List *pathkeys; /* sort ordering of path's output */ 1160 /* pathkeys is a List of PathKey nodes; see above */ 1161 } Path; 1162 1163 /* Macro for extracting a path's parameterization relids; beware double eval */ 1164 #define PATH_REQ_OUTER(path) \ 1165 ((path)->param_info ? (path)->param_info->ppi_req_outer : (Relids) NULL) 1166 1167 /*---------- 1168 * IndexPath represents an index scan over a single index. 1169 * 1170 * This struct is used for both regular indexscans and index-only scans; 1171 * path.pathtype is T_IndexScan or T_IndexOnlyScan to show which is meant. 1172 * 1173 * 'indexinfo' is the index to be scanned. 1174 * 1175 * 'indexclauses' is a list of IndexClause nodes, each representing one 1176 * index-checkable restriction, with implicit AND semantics across the list. 1177 * An empty list implies a full index scan. 1178 * 1179 * 'indexorderbys', if not NIL, is a list of ORDER BY expressions that have 1180 * been found to be usable as ordering operators for an amcanorderbyop index. 1181 * The list must match the path's pathkeys, ie, one expression per pathkey 1182 * in the same order. These are not RestrictInfos, just bare expressions, 1183 * since they generally won't yield booleans. It's guaranteed that each 1184 * expression has the index key on the left side of the operator. 1185 * 1186 * 'indexorderbycols' is an integer list of index column numbers (zero-based) 1187 * of the same length as 'indexorderbys', showing which index column each 1188 * ORDER BY expression is meant to be used with. (There is no restriction 1189 * on which index column each ORDER BY can be used with.) 1190 * 1191 * 'indexscandir' is one of: 1192 * ForwardScanDirection: forward scan of an ordered index 1193 * BackwardScanDirection: backward scan of an ordered index 1194 * NoMovementScanDirection: scan of an unordered index, or don't care 1195 * (The executor doesn't care whether it gets ForwardScanDirection or 1196 * NoMovementScanDirection for an indexscan, but the planner wants to 1197 * distinguish ordered from unordered indexes for building pathkeys.) 1198 * 1199 * 'indextotalcost' and 'indexselectivity' are saved in the IndexPath so that 1200 * we need not recompute them when considering using the same index in a 1201 * bitmap index/heap scan (see BitmapHeapPath). The costs of the IndexPath 1202 * itself represent the costs of an IndexScan or IndexOnlyScan plan type. 1203 *---------- 1204 */ 1205 typedef struct IndexPath 1206 { 1207 Path path; 1208 IndexOptInfo *indexinfo; 1209 List *indexclauses; 1210 List *indexorderbys; 1211 List *indexorderbycols; 1212 ScanDirection indexscandir; 1213 Cost indextotalcost; 1214 Selectivity indexselectivity; 1215 } IndexPath; 1216 1217 /* 1218 * Each IndexClause references a RestrictInfo node from the query's WHERE 1219 * or JOIN conditions, and shows how that restriction can be applied to 1220 * the particular index. We support both indexclauses that are directly 1221 * usable by the index machinery, which are typically of the form 1222 * "indexcol OP pseudoconstant", and those from which an indexable qual 1223 * can be derived. The simplest such transformation is that a clause 1224 * of the form "pseudoconstant OP indexcol" can be commuted to produce an 1225 * indexable qual (the index machinery expects the indexcol to be on the 1226 * left always). Another example is that we might be able to extract an 1227 * indexable range condition from a LIKE condition, as in "x LIKE 'foo%bar'" 1228 * giving rise to "x >= 'foo' AND x < 'fop'". Derivation of such lossy 1229 * conditions is done by a planner support function attached to the 1230 * indexclause's top-level function or operator. 1231 * 1232 * indexquals is a list of RestrictInfos for the directly-usable index 1233 * conditions associated with this IndexClause. In the simplest case 1234 * it's a one-element list whose member is iclause->rinfo. Otherwise, 1235 * it contains one or more directly-usable indexqual conditions extracted 1236 * from the given clause. The 'lossy' flag indicates whether the 1237 * indexquals are semantically equivalent to the original clause, or 1238 * represent a weaker condition. 1239 * 1240 * Normally, indexcol is the index of the single index column the clause 1241 * works on, and indexcols is NIL. But if the clause is a RowCompareExpr, 1242 * indexcol is the index of the leading column, and indexcols is a list of 1243 * all the affected columns. (Note that indexcols matches up with the 1244 * columns of the actual indexable RowCompareExpr in indexquals, which 1245 * might be different from the original in rinfo.) 1246 * 1247 * An IndexPath's IndexClause list is required to be ordered by index 1248 * column, i.e. the indexcol values must form a nondecreasing sequence. 1249 * (The order of multiple clauses for the same index column is unspecified.) 1250 */ 1251 typedef struct IndexClause 1252 { 1253 NodeTag type; 1254 struct RestrictInfo *rinfo; /* original restriction or join clause */ 1255 List *indexquals; /* indexqual(s) derived from it */ 1256 bool lossy; /* are indexquals a lossy version of clause? */ 1257 AttrNumber indexcol; /* index column the clause uses (zero-based) */ 1258 List *indexcols; /* multiple index columns, if RowCompare */ 1259 } IndexClause; 1260 1261 /* 1262 * BitmapHeapPath represents one or more indexscans that generate TID bitmaps 1263 * instead of directly accessing the heap, followed by AND/OR combinations 1264 * to produce a single bitmap, followed by a heap scan that uses the bitmap. 1265 * Note that the output is always considered unordered, since it will come 1266 * out in physical heap order no matter what the underlying indexes did. 1267 * 1268 * The individual indexscans are represented by IndexPath nodes, and any 1269 * logic on top of them is represented by a tree of BitmapAndPath and 1270 * BitmapOrPath nodes. Notice that we can use the same IndexPath node both 1271 * to represent a regular (or index-only) index scan plan, and as the child 1272 * of a BitmapHeapPath that represents scanning the same index using a 1273 * BitmapIndexScan. The startup_cost and total_cost figures of an IndexPath 1274 * always represent the costs to use it as a regular (or index-only) 1275 * IndexScan. The costs of a BitmapIndexScan can be computed using the 1276 * IndexPath's indextotalcost and indexselectivity. 1277 */ 1278 typedef struct BitmapHeapPath 1279 { 1280 Path path; 1281 Path *bitmapqual; /* IndexPath, BitmapAndPath, BitmapOrPath */ 1282 } BitmapHeapPath; 1283 1284 /* 1285 * BitmapAndPath represents a BitmapAnd plan node; it can only appear as 1286 * part of the substructure of a BitmapHeapPath. The Path structure is 1287 * a bit more heavyweight than we really need for this, but for simplicity 1288 * we make it a derivative of Path anyway. 1289 */ 1290 typedef struct BitmapAndPath 1291 { 1292 Path path; 1293 List *bitmapquals; /* IndexPaths and BitmapOrPaths */ 1294 Selectivity bitmapselectivity; 1295 } BitmapAndPath; 1296 1297 /* 1298 * BitmapOrPath represents a BitmapOr plan node; it can only appear as 1299 * part of the substructure of a BitmapHeapPath. The Path structure is 1300 * a bit more heavyweight than we really need for this, but for simplicity 1301 * we make it a derivative of Path anyway. 1302 */ 1303 typedef struct BitmapOrPath 1304 { 1305 Path path; 1306 List *bitmapquals; /* IndexPaths and BitmapAndPaths */ 1307 Selectivity bitmapselectivity; 1308 } BitmapOrPath; 1309 1310 /* 1311 * TidPath represents a scan by TID 1312 * 1313 * tidquals is an implicitly OR'ed list of qual expressions of the form 1314 * "CTID = pseudoconstant", or "CTID = ANY(pseudoconstant_array)", 1315 * or a CurrentOfExpr for the relation. 1316 */ 1317 typedef struct TidPath 1318 { 1319 Path path; 1320 List *tidquals; /* qual(s) involving CTID = something */ 1321 } TidPath; 1322 1323 /* 1324 * SubqueryScanPath represents a scan of an unflattened subquery-in-FROM 1325 * 1326 * Note that the subpath comes from a different planning domain; for example 1327 * RTE indexes within it mean something different from those known to the 1328 * SubqueryScanPath. path.parent->subroot is the planning context needed to 1329 * interpret the subpath. 1330 */ 1331 typedef struct SubqueryScanPath 1332 { 1333 Path path; 1334 Path *subpath; /* path representing subquery execution */ 1335 } SubqueryScanPath; 1336 1337 /* 1338 * ForeignPath represents a potential scan of a foreign table, foreign join 1339 * or foreign upper-relation. 1340 * 1341 * fdw_private stores FDW private data about the scan. While fdw_private is 1342 * not actually touched by the core code during normal operations, it's 1343 * generally a good idea to use a representation that can be dumped by 1344 * nodeToString(), so that you can examine the structure during debugging 1345 * with tools like pprint(). 1346 */ 1347 typedef struct ForeignPath 1348 { 1349 Path path; 1350 Path *fdw_outerpath; 1351 List *fdw_private; 1352 } ForeignPath; 1353 1354 /* 1355 * CustomPath represents a table scan done by some out-of-core extension. 1356 * 1357 * We provide a set of hooks here - which the provider must take care to set 1358 * up correctly - to allow extensions to supply their own methods of scanning 1359 * a relation. For example, a provider might provide GPU acceleration, a 1360 * cache-based scan, or some other kind of logic we haven't dreamed up yet. 1361 * 1362 * CustomPaths can be injected into the planning process for a relation by 1363 * set_rel_pathlist_hook functions. 1364 * 1365 * Core code must avoid assuming that the CustomPath is only as large as 1366 * the structure declared here; providers are allowed to make it the first 1367 * element in a larger structure. (Since the planner never copies Paths, 1368 * this doesn't add any complication.) However, for consistency with the 1369 * FDW case, we provide a "custom_private" field in CustomPath; providers 1370 * may prefer to use that rather than define another struct type. 1371 */ 1372 1373 struct CustomPathMethods; 1374 1375 typedef struct CustomPath 1376 { 1377 Path path; 1378 uint32 flags; /* mask of CUSTOMPATH_* flags, see 1379 * nodes/extensible.h */ 1380 List *custom_paths; /* list of child Path nodes, if any */ 1381 List *custom_private; 1382 const struct CustomPathMethods *methods; 1383 } CustomPath; 1384 1385 /* 1386 * AppendPath represents an Append plan, ie, successive execution of 1387 * several member plans. 1388 * 1389 * For partial Append, 'subpaths' contains non-partial subpaths followed by 1390 * partial subpaths. 1391 * 1392 * Note: it is possible for "subpaths" to contain only one, or even no, 1393 * elements. These cases are optimized during create_append_plan. 1394 * In particular, an AppendPath with no subpaths is a "dummy" path that 1395 * is created to represent the case that a relation is provably empty. 1396 * (This is a convenient representation because it means that when we build 1397 * an appendrel and find that all its children have been excluded, no extra 1398 * action is needed to recognize the relation as dummy.) 1399 */ 1400 typedef struct AppendPath 1401 { 1402 Path path; 1403 /* RT indexes of non-leaf tables in a partition tree */ 1404 List *partitioned_rels; 1405 List *subpaths; /* list of component Paths */ 1406 /* Index of first partial path in subpaths; list_length(subpaths) if none */ 1407 int first_partial_path; 1408 double limit_tuples; /* hard limit on output tuples, or -1 */ 1409 } AppendPath; 1410 1411 #define IS_DUMMY_APPEND(p) \ 1412 (IsA((p), AppendPath) && ((AppendPath *) (p))->subpaths == NIL) 1413 1414 /* 1415 * A relation that's been proven empty will have one path that is dummy 1416 * (but might have projection paths on top). For historical reasons, 1417 * this is provided as a macro that wraps is_dummy_rel(). 1418 */ 1419 #define IS_DUMMY_REL(r) is_dummy_rel(r) 1420 extern bool is_dummy_rel(RelOptInfo *rel); 1421 1422 /* 1423 * MergeAppendPath represents a MergeAppend plan, ie, the merging of sorted 1424 * results from several member plans to produce similarly-sorted output. 1425 */ 1426 typedef struct MergeAppendPath 1427 { 1428 Path path; 1429 /* RT indexes of non-leaf tables in a partition tree */ 1430 List *partitioned_rels; 1431 List *subpaths; /* list of component Paths */ 1432 double limit_tuples; /* hard limit on output tuples, or -1 */ 1433 } MergeAppendPath; 1434 1435 /* 1436 * GroupResultPath represents use of a Result plan node to compute the 1437 * output of a degenerate GROUP BY case, wherein we know we should produce 1438 * exactly one row, which might then be filtered by a HAVING qual. 1439 * 1440 * Note that quals is a list of bare clauses, not RestrictInfos. 1441 */ 1442 typedef struct GroupResultPath 1443 { 1444 Path path; 1445 List *quals; 1446 } GroupResultPath; 1447 1448 /* 1449 * MaterialPath represents use of a Material plan node, i.e., caching of 1450 * the output of its subpath. This is used when the subpath is expensive 1451 * and needs to be scanned repeatedly, or when we need mark/restore ability 1452 * and the subpath doesn't have it. 1453 */ 1454 typedef struct MaterialPath 1455 { 1456 Path path; 1457 Path *subpath; 1458 } MaterialPath; 1459 1460 /* 1461 * UniquePath represents elimination of distinct rows from the output of 1462 * its subpath. 1463 * 1464 * This can represent significantly different plans: either hash-based or 1465 * sort-based implementation, or a no-op if the input path can be proven 1466 * distinct already. The decision is sufficiently localized that it's not 1467 * worth having separate Path node types. (Note: in the no-op case, we could 1468 * eliminate the UniquePath node entirely and just return the subpath; but 1469 * it's convenient to have a UniquePath in the path tree to signal upper-level 1470 * routines that the input is known distinct.) 1471 */ 1472 typedef enum 1473 { 1474 UNIQUE_PATH_NOOP, /* input is known unique already */ 1475 UNIQUE_PATH_HASH, /* use hashing */ 1476 UNIQUE_PATH_SORT /* use sorting */ 1477 } UniquePathMethod; 1478 1479 typedef struct UniquePath 1480 { 1481 Path path; 1482 Path *subpath; 1483 UniquePathMethod umethod; 1484 List *in_operators; /* equality operators of the IN clause */ 1485 List *uniq_exprs; /* expressions to be made unique */ 1486 } UniquePath; 1487 1488 /* 1489 * GatherPath runs several copies of a plan in parallel and collects the 1490 * results. The parallel leader may also execute the plan, unless the 1491 * single_copy flag is set. 1492 */ 1493 typedef struct GatherPath 1494 { 1495 Path path; 1496 Path *subpath; /* path for each worker */ 1497 bool single_copy; /* don't execute path more than once */ 1498 int num_workers; /* number of workers sought to help */ 1499 } GatherPath; 1500 1501 /* 1502 * GatherMergePath runs several copies of a plan in parallel and collects 1503 * the results, preserving their common sort order. 1504 */ 1505 typedef struct GatherMergePath 1506 { 1507 Path path; 1508 Path *subpath; /* path for each worker */ 1509 int num_workers; /* number of workers sought to help */ 1510 } GatherMergePath; 1511 1512 1513 /* 1514 * All join-type paths share these fields. 1515 */ 1516 1517 typedef struct JoinPath 1518 { 1519 Path path; 1520 1521 JoinType jointype; 1522 1523 bool inner_unique; /* each outer tuple provably matches no more 1524 * than one inner tuple */ 1525 1526 Path *outerjoinpath; /* path for the outer side of the join */ 1527 Path *innerjoinpath; /* path for the inner side of the join */ 1528 1529 List *joinrestrictinfo; /* RestrictInfos to apply to join */ 1530 1531 /* 1532 * See the notes for RelOptInfo and ParamPathInfo to understand why 1533 * joinrestrictinfo is needed in JoinPath, and can't be merged into the 1534 * parent RelOptInfo. 1535 */ 1536 } JoinPath; 1537 1538 /* 1539 * A nested-loop path needs no special fields. 1540 */ 1541 1542 typedef JoinPath NestPath; 1543 1544 /* 1545 * A mergejoin path has these fields. 1546 * 1547 * Unlike other path types, a MergePath node doesn't represent just a single 1548 * run-time plan node: it can represent up to four. Aside from the MergeJoin 1549 * node itself, there can be a Sort node for the outer input, a Sort node 1550 * for the inner input, and/or a Material node for the inner input. We could 1551 * represent these nodes by separate path nodes, but considering how many 1552 * different merge paths are investigated during a complex join problem, 1553 * it seems better to avoid unnecessary palloc overhead. 1554 * 1555 * path_mergeclauses lists the clauses (in the form of RestrictInfos) 1556 * that will be used in the merge. 1557 * 1558 * Note that the mergeclauses are a subset of the parent relation's 1559 * restriction-clause list. Any join clauses that are not mergejoinable 1560 * appear only in the parent's restrict list, and must be checked by a 1561 * qpqual at execution time. 1562 * 1563 * outersortkeys (resp. innersortkeys) is NIL if the outer path 1564 * (resp. inner path) is already ordered appropriately for the 1565 * mergejoin. If it is not NIL then it is a PathKeys list describing 1566 * the ordering that must be created by an explicit Sort node. 1567 * 1568 * skip_mark_restore is true if the executor need not do mark/restore calls. 1569 * Mark/restore overhead is usually required, but can be skipped if we know 1570 * that the executor need find only one match per outer tuple, and that the 1571 * mergeclauses are sufficient to identify a match. In such cases the 1572 * executor can immediately advance the outer relation after processing a 1573 * match, and therefore it need never back up the inner relation. 1574 * 1575 * materialize_inner is true if a Material node should be placed atop the 1576 * inner input. This may appear with or without an inner Sort step. 1577 */ 1578 1579 typedef struct MergePath 1580 { 1581 JoinPath jpath; 1582 List *path_mergeclauses; /* join clauses to be used for merge */ 1583 List *outersortkeys; /* keys for explicit sort, if any */ 1584 List *innersortkeys; /* keys for explicit sort, if any */ 1585 bool skip_mark_restore; /* can executor skip mark/restore? */ 1586 bool materialize_inner; /* add Materialize to inner? */ 1587 } MergePath; 1588 1589 /* 1590 * A hashjoin path has these fields. 1591 * 1592 * The remarks above for mergeclauses apply for hashclauses as well. 1593 * 1594 * Hashjoin does not care what order its inputs appear in, so we have 1595 * no need for sortkeys. 1596 */ 1597 1598 typedef struct HashPath 1599 { 1600 JoinPath jpath; 1601 List *path_hashclauses; /* join clauses used for hashing */ 1602 int num_batches; /* number of batches expected */ 1603 double inner_rows_total; /* total inner rows expected */ 1604 } HashPath; 1605 1606 /* 1607 * ProjectionPath represents a projection (that is, targetlist computation) 1608 * 1609 * Nominally, this path node represents using a Result plan node to do a 1610 * projection step. However, if the input plan node supports projection, 1611 * we can just modify its output targetlist to do the required calculations 1612 * directly, and not need a Result. In some places in the planner we can just 1613 * jam the desired PathTarget into the input path node (and adjust its cost 1614 * accordingly), so we don't need a ProjectionPath. But in other places 1615 * it's necessary to not modify the input path node, so we need a separate 1616 * ProjectionPath node, which is marked dummy to indicate that we intend to 1617 * assign the work to the input plan node. The estimated cost for the 1618 * ProjectionPath node will account for whether a Result will be used or not. 1619 */ 1620 typedef struct ProjectionPath 1621 { 1622 Path path; 1623 Path *subpath; /* path representing input source */ 1624 bool dummypp; /* true if no separate Result is needed */ 1625 } ProjectionPath; 1626 1627 /* 1628 * ProjectSetPath represents evaluation of a targetlist that includes 1629 * set-returning function(s), which will need to be implemented by a 1630 * ProjectSet plan node. 1631 */ 1632 typedef struct ProjectSetPath 1633 { 1634 Path path; 1635 Path *subpath; /* path representing input source */ 1636 } ProjectSetPath; 1637 1638 /* 1639 * SortPath represents an explicit sort step 1640 * 1641 * The sort keys are, by definition, the same as path.pathkeys. 1642 * 1643 * Note: the Sort plan node cannot project, so path.pathtarget must be the 1644 * same as the input's pathtarget. 1645 */ 1646 typedef struct SortPath 1647 { 1648 Path path; 1649 Path *subpath; /* path representing input source */ 1650 } SortPath; 1651 1652 /* 1653 * IncrementalSortPath represents an incremental sort step 1654 * 1655 * This is like a regular sort, except some leading key columns are assumed 1656 * to be ordered already. 1657 */ 1658 typedef struct IncrementalSortPath 1659 { 1660 SortPath spath; 1661 int nPresortedCols; /* number of presorted columns */ 1662 } IncrementalSortPath; 1663 1664 /* 1665 * GroupPath represents grouping (of presorted input) 1666 * 1667 * groupClause represents the columns to be grouped on; the input path 1668 * must be at least that well sorted. 1669 * 1670 * We can also apply a qual to the grouped rows (equivalent of HAVING) 1671 */ 1672 typedef struct GroupPath 1673 { 1674 Path path; 1675 Path *subpath; /* path representing input source */ 1676 List *groupClause; /* a list of SortGroupClause's */ 1677 List *qual; /* quals (HAVING quals), if any */ 1678 } GroupPath; 1679 1680 /* 1681 * UpperUniquePath represents adjacent-duplicate removal (in presorted input) 1682 * 1683 * The columns to be compared are the first numkeys columns of the path's 1684 * pathkeys. The input is presumed already sorted that way. 1685 */ 1686 typedef struct UpperUniquePath 1687 { 1688 Path path; 1689 Path *subpath; /* path representing input source */ 1690 int numkeys; /* number of pathkey columns to compare */ 1691 } UpperUniquePath; 1692 1693 /* 1694 * AggPath represents generic computation of aggregate functions 1695 * 1696 * This may involve plain grouping (but not grouping sets), using either 1697 * sorted or hashed grouping; for the AGG_SORTED case, the input must be 1698 * appropriately presorted. 1699 */ 1700 typedef struct AggPath 1701 { 1702 Path path; 1703 Path *subpath; /* path representing input source */ 1704 AggStrategy aggstrategy; /* basic strategy, see nodes.h */ 1705 AggSplit aggsplit; /* agg-splitting mode, see nodes.h */ 1706 double numGroups; /* estimated number of groups in input */ 1707 uint64 transitionSpace; /* for pass-by-ref transition data */ 1708 List *groupClause; /* a list of SortGroupClause's */ 1709 List *qual; /* quals (HAVING quals), if any */ 1710 } AggPath; 1711 1712 /* 1713 * Various annotations used for grouping sets in the planner. 1714 */ 1715 1716 typedef struct GroupingSetData 1717 { 1718 NodeTag type; 1719 List *set; /* grouping set as list of sortgrouprefs */ 1720 double numGroups; /* est. number of result groups */ 1721 } GroupingSetData; 1722 1723 typedef struct RollupData 1724 { 1725 NodeTag type; 1726 List *groupClause; /* applicable subset of parse->groupClause */ 1727 List *gsets; /* lists of integer indexes into groupClause */ 1728 List *gsets_data; /* list of GroupingSetData */ 1729 double numGroups; /* est. number of result groups */ 1730 bool hashable; /* can be hashed */ 1731 bool is_hashed; /* to be implemented as a hashagg */ 1732 } RollupData; 1733 1734 /* 1735 * GroupingSetsPath represents a GROUPING SETS aggregation 1736 */ 1737 1738 typedef struct GroupingSetsPath 1739 { 1740 Path path; 1741 Path *subpath; /* path representing input source */ 1742 AggStrategy aggstrategy; /* basic strategy */ 1743 List *rollups; /* list of RollupData */ 1744 List *qual; /* quals (HAVING quals), if any */ 1745 uint64 transitionSpace; /* for pass-by-ref transition data */ 1746 } GroupingSetsPath; 1747 1748 /* 1749 * MinMaxAggPath represents computation of MIN/MAX aggregates from indexes 1750 */ 1751 typedef struct MinMaxAggPath 1752 { 1753 Path path; 1754 List *mmaggregates; /* list of MinMaxAggInfo */ 1755 List *quals; /* HAVING quals, if any */ 1756 } MinMaxAggPath; 1757 1758 /* 1759 * WindowAggPath represents generic computation of window functions 1760 */ 1761 typedef struct WindowAggPath 1762 { 1763 Path path; 1764 Path *subpath; /* path representing input source */ 1765 WindowClause *winclause; /* WindowClause we'll be using */ 1766 } WindowAggPath; 1767 1768 /* 1769 * SetOpPath represents a set-operation, that is INTERSECT or EXCEPT 1770 */ 1771 typedef struct SetOpPath 1772 { 1773 Path path; 1774 Path *subpath; /* path representing input source */ 1775 SetOpCmd cmd; /* what to do, see nodes.h */ 1776 SetOpStrategy strategy; /* how to do it, see nodes.h */ 1777 List *distinctList; /* SortGroupClauses identifying target cols */ 1778 AttrNumber flagColIdx; /* where is the flag column, if any */ 1779 int firstFlag; /* flag value for first input relation */ 1780 double numGroups; /* estimated number of groups in input */ 1781 } SetOpPath; 1782 1783 /* 1784 * RecursiveUnionPath represents a recursive UNION node 1785 */ 1786 typedef struct RecursiveUnionPath 1787 { 1788 Path path; 1789 Path *leftpath; /* paths representing input sources */ 1790 Path *rightpath; 1791 List *distinctList; /* SortGroupClauses identifying target cols */ 1792 int wtParam; /* ID of Param representing work table */ 1793 double numGroups; /* estimated number of groups in input */ 1794 } RecursiveUnionPath; 1795 1796 /* 1797 * LockRowsPath represents acquiring row locks for SELECT FOR UPDATE/SHARE 1798 */ 1799 typedef struct LockRowsPath 1800 { 1801 Path path; 1802 Path *subpath; /* path representing input source */ 1803 List *rowMarks; /* a list of PlanRowMark's */ 1804 int epqParam; /* ID of Param for EvalPlanQual re-eval */ 1805 } LockRowsPath; 1806 1807 /* 1808 * ModifyTablePath represents performing INSERT/UPDATE/DELETE modifications 1809 * 1810 * We represent most things that will be in the ModifyTable plan node 1811 * literally, except we have child Path(s) not Plan(s). But analysis of the 1812 * OnConflictExpr is deferred to createplan.c, as is collection of FDW data. 1813 */ 1814 typedef struct ModifyTablePath 1815 { 1816 Path path; 1817 CmdType operation; /* INSERT, UPDATE, or DELETE */ 1818 bool canSetTag; /* do we set the command tag/es_processed? */ 1819 Index nominalRelation; /* Parent RT index for use of EXPLAIN */ 1820 Index rootRelation; /* Root RT index, if target is partitioned */ 1821 bool partColsUpdated; /* some part key in hierarchy updated */ 1822 List *resultRelations; /* integer list of RT indexes */ 1823 List *subpaths; /* Path(s) producing source data */ 1824 List *subroots; /* per-target-table PlannerInfos */ 1825 List *withCheckOptionLists; /* per-target-table WCO lists */ 1826 List *returningLists; /* per-target-table RETURNING tlists */ 1827 List *rowMarks; /* PlanRowMarks (non-locking only) */ 1828 OnConflictExpr *onconflict; /* ON CONFLICT clause, or NULL */ 1829 int epqParam; /* ID of Param for EvalPlanQual re-eval */ 1830 } ModifyTablePath; 1831 1832 /* 1833 * LimitPath represents applying LIMIT/OFFSET restrictions 1834 */ 1835 typedef struct LimitPath 1836 { 1837 Path path; 1838 Path *subpath; /* path representing input source */ 1839 Node *limitOffset; /* OFFSET parameter, or NULL if none */ 1840 Node *limitCount; /* COUNT parameter, or NULL if none */ 1841 LimitOption limitOption; /* FETCH FIRST with ties or exact number */ 1842 } LimitPath; 1843 1844 1845 /* 1846 * Restriction clause info. 1847 * 1848 * We create one of these for each AND sub-clause of a restriction condition 1849 * (WHERE or JOIN/ON clause). Since the restriction clauses are logically 1850 * ANDed, we can use any one of them or any subset of them to filter out 1851 * tuples, without having to evaluate the rest. The RestrictInfo node itself 1852 * stores data used by the optimizer while choosing the best query plan. 1853 * 1854 * If a restriction clause references a single base relation, it will appear 1855 * in the baserestrictinfo list of the RelOptInfo for that base rel. 1856 * 1857 * If a restriction clause references more than one base rel, it will 1858 * appear in the joininfo list of every RelOptInfo that describes a strict 1859 * subset of the base rels mentioned in the clause. The joininfo lists are 1860 * used to drive join tree building by selecting plausible join candidates. 1861 * The clause cannot actually be applied until we have built a join rel 1862 * containing all the base rels it references, however. 1863 * 1864 * When we construct a join rel that includes all the base rels referenced 1865 * in a multi-relation restriction clause, we place that clause into the 1866 * joinrestrictinfo lists of paths for the join rel, if neither left nor 1867 * right sub-path includes all base rels referenced in the clause. The clause 1868 * will be applied at that join level, and will not propagate any further up 1869 * the join tree. (Note: the "predicate migration" code was once intended to 1870 * push restriction clauses up and down the plan tree based on evaluation 1871 * costs, but it's dead code and is unlikely to be resurrected in the 1872 * foreseeable future.) 1873 * 1874 * Note that in the presence of more than two rels, a multi-rel restriction 1875 * might reach different heights in the join tree depending on the join 1876 * sequence we use. So, these clauses cannot be associated directly with 1877 * the join RelOptInfo, but must be kept track of on a per-join-path basis. 1878 * 1879 * RestrictInfos that represent equivalence conditions (i.e., mergejoinable 1880 * equalities that are not outerjoin-delayed) are handled a bit differently. 1881 * Initially we attach them to the EquivalenceClasses that are derived from 1882 * them. When we construct a scan or join path, we look through all the 1883 * EquivalenceClasses and generate derived RestrictInfos representing the 1884 * minimal set of conditions that need to be checked for this particular scan 1885 * or join to enforce that all members of each EquivalenceClass are in fact 1886 * equal in all rows emitted by the scan or join. 1887 * 1888 * When dealing with outer joins we have to be very careful about pushing qual 1889 * clauses up and down the tree. An outer join's own JOIN/ON conditions must 1890 * be evaluated exactly at that join node, unless they are "degenerate" 1891 * conditions that reference only Vars from the nullable side of the join. 1892 * Quals appearing in WHERE or in a JOIN above the outer join cannot be pushed 1893 * down below the outer join, if they reference any nullable Vars. 1894 * RestrictInfo nodes contain a flag to indicate whether a qual has been 1895 * pushed down to a lower level than its original syntactic placement in the 1896 * join tree would suggest. If an outer join prevents us from pushing a qual 1897 * down to its "natural" semantic level (the level associated with just the 1898 * base rels used in the qual) then we mark the qual with a "required_relids" 1899 * value including more than just the base rels it actually uses. By 1900 * pretending that the qual references all the rels required to form the outer 1901 * join, we prevent it from being evaluated below the outer join's joinrel. 1902 * When we do form the outer join's joinrel, we still need to distinguish 1903 * those quals that are actually in that join's JOIN/ON condition from those 1904 * that appeared elsewhere in the tree and were pushed down to the join rel 1905 * because they used no other rels. That's what the is_pushed_down flag is 1906 * for; it tells us that a qual is not an OUTER JOIN qual for the set of base 1907 * rels listed in required_relids. A clause that originally came from WHERE 1908 * or an INNER JOIN condition will *always* have its is_pushed_down flag set. 1909 * It's possible for an OUTER JOIN clause to be marked is_pushed_down too, 1910 * if we decide that it can be pushed down into the nullable side of the join. 1911 * In that case it acts as a plain filter qual for wherever it gets evaluated. 1912 * (In short, is_pushed_down is only false for non-degenerate outer join 1913 * conditions. Possibly we should rename it to reflect that meaning? But 1914 * see also the comments for RINFO_IS_PUSHED_DOWN, below.) 1915 * 1916 * RestrictInfo nodes also contain an outerjoin_delayed flag, which is true 1917 * if the clause's applicability must be delayed due to any outer joins 1918 * appearing below it (ie, it has to be postponed to some join level higher 1919 * than the set of relations it actually references). 1920 * 1921 * There is also an outer_relids field, which is NULL except for outer join 1922 * clauses; for those, it is the set of relids on the outer side of the 1923 * clause's outer join. (These are rels that the clause cannot be applied to 1924 * in parameterized scans, since pushing it into the join's outer side would 1925 * lead to wrong answers.) 1926 * 1927 * There is also a nullable_relids field, which is the set of rels the clause 1928 * references that can be forced null by some outer join below the clause. 1929 * 1930 * outerjoin_delayed = true is subtly different from nullable_relids != NULL: 1931 * a clause might reference some nullable rels and yet not be 1932 * outerjoin_delayed because it also references all the other rels of the 1933 * outer join(s). A clause that is not outerjoin_delayed can be enforced 1934 * anywhere it is computable. 1935 * 1936 * To handle security-barrier conditions efficiently, we mark RestrictInfo 1937 * nodes with a security_level field, in which higher values identify clauses 1938 * coming from less-trusted sources. The exact semantics are that a clause 1939 * cannot be evaluated before another clause with a lower security_level value 1940 * unless the first clause is leakproof. As with outer-join clauses, this 1941 * creates a reason for clauses to sometimes need to be evaluated higher in 1942 * the join tree than their contents would suggest; and even at a single plan 1943 * node, this rule constrains the order of application of clauses. 1944 * 1945 * In general, the referenced clause might be arbitrarily complex. The 1946 * kinds of clauses we can handle as indexscan quals, mergejoin clauses, 1947 * or hashjoin clauses are limited (e.g., no volatile functions). The code 1948 * for each kind of path is responsible for identifying the restrict clauses 1949 * it can use and ignoring the rest. Clauses not implemented by an indexscan, 1950 * mergejoin, or hashjoin will be placed in the plan qual or joinqual field 1951 * of the finished Plan node, where they will be enforced by general-purpose 1952 * qual-expression-evaluation code. (But we are still entitled to count 1953 * their selectivity when estimating the result tuple count, if we 1954 * can guess what it is...) 1955 * 1956 * When the referenced clause is an OR clause, we generate a modified copy 1957 * in which additional RestrictInfo nodes are inserted below the top-level 1958 * OR/AND structure. This is a convenience for OR indexscan processing: 1959 * indexquals taken from either the top level or an OR subclause will have 1960 * associated RestrictInfo nodes. 1961 * 1962 * The can_join flag is set true if the clause looks potentially useful as 1963 * a merge or hash join clause, that is if it is a binary opclause with 1964 * nonoverlapping sets of relids referenced in the left and right sides. 1965 * (Whether the operator is actually merge or hash joinable isn't checked, 1966 * however.) 1967 * 1968 * The pseudoconstant flag is set true if the clause contains no Vars of 1969 * the current query level and no volatile functions. Such a clause can be 1970 * pulled out and used as a one-time qual in a gating Result node. We keep 1971 * pseudoconstant clauses in the same lists as other RestrictInfos so that 1972 * the regular clause-pushing machinery can assign them to the correct join 1973 * level, but they need to be treated specially for cost and selectivity 1974 * estimates. Note that a pseudoconstant clause can never be an indexqual 1975 * or merge or hash join clause, so it's of no interest to large parts of 1976 * the planner. 1977 * 1978 * When join clauses are generated from EquivalenceClasses, there may be 1979 * several equally valid ways to enforce join equivalence, of which we need 1980 * apply only one. We mark clauses of this kind by setting parent_ec to 1981 * point to the generating EquivalenceClass. Multiple clauses with the same 1982 * parent_ec in the same join are redundant. 1983 */ 1984 1985 typedef struct RestrictInfo 1986 { 1987 NodeTag type; 1988 1989 Expr *clause; /* the represented clause of WHERE or JOIN */ 1990 1991 bool is_pushed_down; /* true if clause was pushed down in level */ 1992 1993 bool outerjoin_delayed; /* true if delayed by lower outer join */ 1994 1995 bool can_join; /* see comment above */ 1996 1997 bool pseudoconstant; /* see comment above */ 1998 1999 bool leakproof; /* true if known to contain no leaked Vars */ 2000 2001 Index security_level; /* see comment above */ 2002 2003 /* The set of relids (varnos) actually referenced in the clause: */ 2004 Relids clause_relids; 2005 2006 /* The set of relids required to evaluate the clause: */ 2007 Relids required_relids; 2008 2009 /* If an outer-join clause, the outer-side relations, else NULL: */ 2010 Relids outer_relids; 2011 2012 /* The relids used in the clause that are nullable by lower outer joins: */ 2013 Relids nullable_relids; 2014 2015 /* These fields are set for any binary opclause: */ 2016 Relids left_relids; /* relids in left side of clause */ 2017 Relids right_relids; /* relids in right side of clause */ 2018 2019 /* This field is NULL unless clause is an OR clause: */ 2020 Expr *orclause; /* modified clause with RestrictInfos */ 2021 2022 /* This field is NULL unless clause is potentially redundant: */ 2023 EquivalenceClass *parent_ec; /* generating EquivalenceClass */ 2024 2025 /* cache space for cost and selectivity */ 2026 QualCost eval_cost; /* eval cost of clause; -1 if not yet set */ 2027 Selectivity norm_selec; /* selectivity for "normal" (JOIN_INNER) 2028 * semantics; -1 if not yet set; >1 means a 2029 * redundant clause */ 2030 Selectivity outer_selec; /* selectivity for outer join semantics; -1 if 2031 * not yet set */ 2032 2033 /* valid if clause is mergejoinable, else NIL */ 2034 List *mergeopfamilies; /* opfamilies containing clause operator */ 2035 2036 /* cache space for mergeclause processing; NULL if not yet set */ 2037 EquivalenceClass *left_ec; /* EquivalenceClass containing lefthand */ 2038 EquivalenceClass *right_ec; /* EquivalenceClass containing righthand */ 2039 EquivalenceMember *left_em; /* EquivalenceMember for lefthand */ 2040 EquivalenceMember *right_em; /* EquivalenceMember for righthand */ 2041 List *scansel_cache; /* list of MergeScanSelCache structs */ 2042 2043 /* transient workspace for use while considering a specific join path */ 2044 bool outer_is_left; /* T = outer var on left, F = on right */ 2045 2046 /* valid if clause is hashjoinable, else InvalidOid: */ 2047 Oid hashjoinoperator; /* copy of clause operator */ 2048 2049 /* cache space for hashclause processing; -1 if not yet set */ 2050 Selectivity left_bucketsize; /* avg bucketsize of left side */ 2051 Selectivity right_bucketsize; /* avg bucketsize of right side */ 2052 Selectivity left_mcvfreq; /* left side's most common val's freq */ 2053 Selectivity right_mcvfreq; /* right side's most common val's freq */ 2054 } RestrictInfo; 2055 2056 /* 2057 * This macro embodies the correct way to test whether a RestrictInfo is 2058 * "pushed down" to a given outer join, that is, should be treated as a filter 2059 * clause rather than a join clause at that outer join. This is certainly so 2060 * if is_pushed_down is true; but examining that is not sufficient anymore, 2061 * because outer-join clauses will get pushed down to lower outer joins when 2062 * we generate a path for the lower outer join that is parameterized by the 2063 * LHS of the upper one. We can detect such a clause by noting that its 2064 * required_relids exceed the scope of the join. 2065 */ 2066 #define RINFO_IS_PUSHED_DOWN(rinfo, joinrelids) \ 2067 ((rinfo)->is_pushed_down || \ 2068 !bms_is_subset((rinfo)->required_relids, joinrelids)) 2069 2070 /* 2071 * Since mergejoinscansel() is a relatively expensive function, and would 2072 * otherwise be invoked many times while planning a large join tree, 2073 * we go out of our way to cache its results. Each mergejoinable 2074 * RestrictInfo carries a list of the specific sort orderings that have 2075 * been considered for use with it, and the resulting selectivities. 2076 */ 2077 typedef struct MergeScanSelCache 2078 { 2079 /* Ordering details (cache lookup key) */ 2080 Oid opfamily; /* btree opfamily defining the ordering */ 2081 Oid collation; /* collation for the ordering */ 2082 int strategy; /* sort direction (ASC or DESC) */ 2083 bool nulls_first; /* do NULLs come before normal values? */ 2084 /* Results */ 2085 Selectivity leftstartsel; /* first-join fraction for clause left side */ 2086 Selectivity leftendsel; /* last-join fraction for clause left side */ 2087 Selectivity rightstartsel; /* first-join fraction for clause right side */ 2088 Selectivity rightendsel; /* last-join fraction for clause right side */ 2089 } MergeScanSelCache; 2090 2091 /* 2092 * Placeholder node for an expression to be evaluated below the top level 2093 * of a plan tree. This is used during planning to represent the contained 2094 * expression. At the end of the planning process it is replaced by either 2095 * the contained expression or a Var referring to a lower-level evaluation of 2096 * the contained expression. Typically the evaluation occurs below an outer 2097 * join, and Var references above the outer join might thereby yield NULL 2098 * instead of the expression value. 2099 * 2100 * Although the planner treats this as an expression node type, it is not 2101 * recognized by the parser or executor, so we declare it here rather than 2102 * in primnodes.h. 2103 */ 2104 2105 typedef struct PlaceHolderVar 2106 { 2107 Expr xpr; 2108 Expr *phexpr; /* the represented expression */ 2109 Relids phrels; /* base relids syntactically within expr src */ 2110 Index phid; /* ID for PHV (unique within planner run) */ 2111 Index phlevelsup; /* > 0 if PHV belongs to outer query */ 2112 } PlaceHolderVar; 2113 2114 /* 2115 * "Special join" info. 2116 * 2117 * One-sided outer joins constrain the order of joining partially but not 2118 * completely. We flatten such joins into the planner's top-level list of 2119 * relations to join, but record information about each outer join in a 2120 * SpecialJoinInfo struct. These structs are kept in the PlannerInfo node's 2121 * join_info_list. 2122 * 2123 * Similarly, semijoins and antijoins created by flattening IN (subselect) 2124 * and EXISTS(subselect) clauses create partial constraints on join order. 2125 * These are likewise recorded in SpecialJoinInfo structs. 2126 * 2127 * We make SpecialJoinInfos for FULL JOINs even though there is no flexibility 2128 * of planning for them, because this simplifies make_join_rel()'s API. 2129 * 2130 * min_lefthand and min_righthand are the sets of base relids that must be 2131 * available on each side when performing the special join. lhs_strict is 2132 * true if the special join's condition cannot succeed when the LHS variables 2133 * are all NULL (this means that an outer join can commute with upper-level 2134 * outer joins even if it appears in their RHS). We don't bother to set 2135 * lhs_strict for FULL JOINs, however. 2136 * 2137 * It is not valid for either min_lefthand or min_righthand to be empty sets; 2138 * if they were, this would break the logic that enforces join order. 2139 * 2140 * syn_lefthand and syn_righthand are the sets of base relids that are 2141 * syntactically below this special join. (These are needed to help compute 2142 * min_lefthand and min_righthand for higher joins.) 2143 * 2144 * delay_upper_joins is set true if we detect a pushed-down clause that has 2145 * to be evaluated after this join is formed (because it references the RHS). 2146 * Any outer joins that have such a clause and this join in their RHS cannot 2147 * commute with this join, because that would leave noplace to check the 2148 * pushed-down clause. (We don't track this for FULL JOINs, either.) 2149 * 2150 * For a semijoin, we also extract the join operators and their RHS arguments 2151 * and set semi_operators, semi_rhs_exprs, semi_can_btree, and semi_can_hash. 2152 * This is done in support of possibly unique-ifying the RHS, so we don't 2153 * bother unless at least one of semi_can_btree and semi_can_hash can be set 2154 * true. (You might expect that this information would be computed during 2155 * join planning; but it's helpful to have it available during planning of 2156 * parameterized table scans, so we store it in the SpecialJoinInfo structs.) 2157 * 2158 * jointype is never JOIN_RIGHT; a RIGHT JOIN is handled by switching 2159 * the inputs to make it a LEFT JOIN. So the allowed values of jointype 2160 * in a join_info_list member are only LEFT, FULL, SEMI, or ANTI. 2161 * 2162 * For purposes of join selectivity estimation, we create transient 2163 * SpecialJoinInfo structures for regular inner joins; so it is possible 2164 * to have jointype == JOIN_INNER in such a structure, even though this is 2165 * not allowed within join_info_list. We also create transient 2166 * SpecialJoinInfos with jointype == JOIN_INNER for outer joins, since for 2167 * cost estimation purposes it is sometimes useful to know the join size under 2168 * plain innerjoin semantics. Note that lhs_strict, delay_upper_joins, and 2169 * of course the semi_xxx fields are not set meaningfully within such structs. 2170 */ 2171 #ifndef HAVE_SPECIALJOININFO_TYPEDEF 2172 typedef struct SpecialJoinInfo SpecialJoinInfo; 2173 #define HAVE_SPECIALJOININFO_TYPEDEF 1 2174 #endif 2175 2176 struct SpecialJoinInfo 2177 { 2178 NodeTag type; 2179 Relids min_lefthand; /* base relids in minimum LHS for join */ 2180 Relids min_righthand; /* base relids in minimum RHS for join */ 2181 Relids syn_lefthand; /* base relids syntactically within LHS */ 2182 Relids syn_righthand; /* base relids syntactically within RHS */ 2183 JoinType jointype; /* always INNER, LEFT, FULL, SEMI, or ANTI */ 2184 bool lhs_strict; /* joinclause is strict for some LHS rel */ 2185 bool delay_upper_joins; /* can't commute with upper RHS */ 2186 /* Remaining fields are set only for JOIN_SEMI jointype: */ 2187 bool semi_can_btree; /* true if semi_operators are all btree */ 2188 bool semi_can_hash; /* true if semi_operators are all hash */ 2189 List *semi_operators; /* OIDs of equality join operators */ 2190 List *semi_rhs_exprs; /* righthand-side expressions of these ops */ 2191 }; 2192 2193 /* 2194 * Append-relation info. 2195 * 2196 * When we expand an inheritable table or a UNION-ALL subselect into an 2197 * "append relation" (essentially, a list of child RTEs), we build an 2198 * AppendRelInfo for each child RTE. The list of AppendRelInfos indicates 2199 * which child RTEs must be included when expanding the parent, and each node 2200 * carries information needed to translate between columns of the parent and 2201 * columns of the child. 2202 * 2203 * These structs are kept in the PlannerInfo node's append_rel_list, with 2204 * append_rel_array[] providing a convenient lookup method for the struct 2205 * associated with a particular child relid (there can be only one, though 2206 * parent rels may have many entries in append_rel_list). 2207 * 2208 * Note: after completion of the planner prep phase, any given RTE is an 2209 * append parent having entries in append_rel_list if and only if its 2210 * "inh" flag is set. We clear "inh" for plain tables that turn out not 2211 * to have inheritance children, and (in an abuse of the original meaning 2212 * of the flag) we set "inh" for subquery RTEs that turn out to be 2213 * flattenable UNION ALL queries. This lets us avoid useless searches 2214 * of append_rel_list. 2215 * 2216 * Note: the data structure assumes that append-rel members are single 2217 * baserels. This is OK for inheritance, but it prevents us from pulling 2218 * up a UNION ALL member subquery if it contains a join. While that could 2219 * be fixed with a more complex data structure, at present there's not much 2220 * point because no improvement in the plan could result. 2221 */ 2222 2223 typedef struct AppendRelInfo 2224 { 2225 NodeTag type; 2226 2227 /* 2228 * These fields uniquely identify this append relationship. There can be 2229 * (in fact, always should be) multiple AppendRelInfos for the same 2230 * parent_relid, but never more than one per child_relid, since a given 2231 * RTE cannot be a child of more than one append parent. 2232 */ 2233 Index parent_relid; /* RT index of append parent rel */ 2234 Index child_relid; /* RT index of append child rel */ 2235 2236 /* 2237 * For an inheritance appendrel, the parent and child are both regular 2238 * relations, and we store their rowtype OIDs here for use in translating 2239 * whole-row Vars. For a UNION-ALL appendrel, the parent and child are 2240 * both subqueries with no named rowtype, and we store InvalidOid here. 2241 */ 2242 Oid parent_reltype; /* OID of parent's composite type */ 2243 Oid child_reltype; /* OID of child's composite type */ 2244 2245 /* 2246 * The N'th element of this list is a Var or expression representing the 2247 * child column corresponding to the N'th column of the parent. This is 2248 * used to translate Vars referencing the parent rel into references to 2249 * the child. A list element is NULL if it corresponds to a dropped 2250 * column of the parent (this is only possible for inheritance cases, not 2251 * UNION ALL). The list elements are always simple Vars for inheritance 2252 * cases, but can be arbitrary expressions in UNION ALL cases. 2253 * 2254 * Notice we only store entries for user columns (attno > 0). Whole-row 2255 * Vars are special-cased, and system columns (attno < 0) need no special 2256 * translation since their attnos are the same for all tables. 2257 * 2258 * Caution: the Vars have varlevelsup = 0. Be careful to adjust as needed 2259 * when copying into a subquery. 2260 */ 2261 List *translated_vars; /* Expressions in the child's Vars */ 2262 2263 /* 2264 * This array simplifies translations in the reverse direction, from 2265 * child's column numbers to parent's. The entry at [ccolno - 1] is the 2266 * 1-based parent column number for child column ccolno, or zero if that 2267 * child column is dropped or doesn't exist in the parent. 2268 */ 2269 int num_child_cols; /* length of array */ 2270 AttrNumber *parent_colnos; /* array of parent attnos, or zeroes */ 2271 2272 /* 2273 * We store the parent table's OID here for inheritance, or InvalidOid for 2274 * UNION ALL. This is only needed to help in generating error messages if 2275 * an attempt is made to reference a dropped parent column. 2276 */ 2277 Oid parent_reloid; /* OID of parent relation */ 2278 } AppendRelInfo; 2279 2280 /* 2281 * For each distinct placeholder expression generated during planning, we 2282 * store a PlaceHolderInfo node in the PlannerInfo node's placeholder_list. 2283 * This stores info that is needed centrally rather than in each copy of the 2284 * PlaceHolderVar. The phid fields identify which PlaceHolderInfo goes with 2285 * each PlaceHolderVar. Note that phid is unique throughout a planner run, 2286 * not just within a query level --- this is so that we need not reassign ID's 2287 * when pulling a subquery into its parent. 2288 * 2289 * The idea is to evaluate the expression at (only) the ph_eval_at join level, 2290 * then allow it to bubble up like a Var until the ph_needed join level. 2291 * ph_needed has the same definition as attr_needed for a regular Var. 2292 * 2293 * The PlaceHolderVar's expression might contain LATERAL references to vars 2294 * coming from outside its syntactic scope. If so, those rels are *not* 2295 * included in ph_eval_at, but they are recorded in ph_lateral. 2296 * 2297 * Notice that when ph_eval_at is a join rather than a single baserel, the 2298 * PlaceHolderInfo may create constraints on join order: the ph_eval_at join 2299 * has to be formed below any outer joins that should null the PlaceHolderVar. 2300 * 2301 * We create a PlaceHolderInfo only after determining that the PlaceHolderVar 2302 * is actually referenced in the plan tree, so that unreferenced placeholders 2303 * don't result in unnecessary constraints on join order. 2304 */ 2305 2306 typedef struct PlaceHolderInfo 2307 { 2308 NodeTag type; 2309 2310 Index phid; /* ID for PH (unique within planner run) */ 2311 PlaceHolderVar *ph_var; /* copy of PlaceHolderVar tree */ 2312 Relids ph_eval_at; /* lowest level we can evaluate value at */ 2313 Relids ph_lateral; /* relids of contained lateral refs, if any */ 2314 Relids ph_needed; /* highest level the value is needed at */ 2315 int32 ph_width; /* estimated attribute width */ 2316 } PlaceHolderInfo; 2317 2318 /* 2319 * This struct describes one potentially index-optimizable MIN/MAX aggregate 2320 * function. MinMaxAggPath contains a list of these, and if we accept that 2321 * path, the list is stored into root->minmax_aggs for use during setrefs.c. 2322 */ 2323 typedef struct MinMaxAggInfo 2324 { 2325 NodeTag type; 2326 2327 Oid aggfnoid; /* pg_proc Oid of the aggregate */ 2328 Oid aggsortop; /* Oid of its sort operator */ 2329 Expr *target; /* expression we are aggregating on */ 2330 PlannerInfo *subroot; /* modified "root" for planning the subquery */ 2331 Path *path; /* access path for subquery */ 2332 Cost pathcost; /* estimated cost to fetch first row */ 2333 Param *param; /* param for subplan's output */ 2334 } MinMaxAggInfo; 2335 2336 /* 2337 * At runtime, PARAM_EXEC slots are used to pass values around from one plan 2338 * node to another. They can be used to pass values down into subqueries (for 2339 * outer references in subqueries), or up out of subqueries (for the results 2340 * of a subplan), or from a NestLoop plan node into its inner relation (when 2341 * the inner scan is parameterized with values from the outer relation). 2342 * The planner is responsible for assigning nonconflicting PARAM_EXEC IDs to 2343 * the PARAM_EXEC Params it generates. 2344 * 2345 * Outer references are managed via root->plan_params, which is a list of 2346 * PlannerParamItems. While planning a subquery, each parent query level's 2347 * plan_params contains the values required from it by the current subquery. 2348 * During create_plan(), we use plan_params to track values that must be 2349 * passed from outer to inner sides of NestLoop plan nodes. 2350 * 2351 * The item a PlannerParamItem represents can be one of three kinds: 2352 * 2353 * A Var: the slot represents a variable of this level that must be passed 2354 * down because subqueries have outer references to it, or must be passed 2355 * from a NestLoop node to its inner scan. The varlevelsup value in the Var 2356 * will always be zero. 2357 * 2358 * A PlaceHolderVar: this works much like the Var case, except that the 2359 * entry is a PlaceHolderVar node with a contained expression. The PHV 2360 * will have phlevelsup = 0, and the contained expression is adjusted 2361 * to match in level. 2362 * 2363 * An Aggref (with an expression tree representing its argument): the slot 2364 * represents an aggregate expression that is an outer reference for some 2365 * subquery. The Aggref itself has agglevelsup = 0, and its argument tree 2366 * is adjusted to match in level. 2367 * 2368 * Note: we detect duplicate Var and PlaceHolderVar parameters and coalesce 2369 * them into one slot, but we do not bother to do that for Aggrefs. 2370 * The scope of duplicate-elimination only extends across the set of 2371 * parameters passed from one query level into a single subquery, or for 2372 * nestloop parameters across the set of nestloop parameters used in a single 2373 * query level. So there is no possibility of a PARAM_EXEC slot being used 2374 * for conflicting purposes. 2375 * 2376 * In addition, PARAM_EXEC slots are assigned for Params representing outputs 2377 * from subplans (values that are setParam items for those subplans). These 2378 * IDs need not be tracked via PlannerParamItems, since we do not need any 2379 * duplicate-elimination nor later processing of the represented expressions. 2380 * Instead, we just record the assignment of the slot number by appending to 2381 * root->glob->paramExecTypes. 2382 */ 2383 typedef struct PlannerParamItem 2384 { 2385 NodeTag type; 2386 2387 Node *item; /* the Var, PlaceHolderVar, or Aggref */ 2388 int paramId; /* its assigned PARAM_EXEC slot number */ 2389 } PlannerParamItem; 2390 2391 /* 2392 * When making cost estimates for a SEMI/ANTI/inner_unique join, there are 2393 * some correction factors that are needed in both nestloop and hash joins 2394 * to account for the fact that the executor can stop scanning inner rows 2395 * as soon as it finds a match to the current outer row. These numbers 2396 * depend only on the selected outer and inner join relations, not on the 2397 * particular paths used for them, so it's worthwhile to calculate them 2398 * just once per relation pair not once per considered path. This struct 2399 * is filled by compute_semi_anti_join_factors and must be passed along 2400 * to the join cost estimation functions. 2401 * 2402 * outer_match_frac is the fraction of the outer tuples that are 2403 * expected to have at least one match. 2404 * match_count is the average number of matches expected for 2405 * outer tuples that have at least one match. 2406 */ 2407 typedef struct SemiAntiJoinFactors 2408 { 2409 Selectivity outer_match_frac; 2410 Selectivity match_count; 2411 } SemiAntiJoinFactors; 2412 2413 /* 2414 * Struct for extra information passed to subroutines of add_paths_to_joinrel 2415 * 2416 * restrictlist contains all of the RestrictInfo nodes for restriction 2417 * clauses that apply to this join 2418 * mergeclause_list is a list of RestrictInfo nodes for available 2419 * mergejoin clauses in this join 2420 * inner_unique is true if each outer tuple provably matches no more 2421 * than one inner tuple 2422 * sjinfo is extra info about special joins for selectivity estimation 2423 * semifactors is as shown above (only valid for SEMI/ANTI/inner_unique joins) 2424 * param_source_rels are OK targets for parameterization of result paths 2425 */ 2426 typedef struct JoinPathExtraData 2427 { 2428 List *restrictlist; 2429 List *mergeclause_list; 2430 bool inner_unique; 2431 SpecialJoinInfo *sjinfo; 2432 SemiAntiJoinFactors semifactors; 2433 Relids param_source_rels; 2434 } JoinPathExtraData; 2435 2436 /* 2437 * Various flags indicating what kinds of grouping are possible. 2438 * 2439 * GROUPING_CAN_USE_SORT should be set if it's possible to perform 2440 * sort-based implementations of grouping. When grouping sets are in use, 2441 * this will be true if sorting is potentially usable for any of the grouping 2442 * sets, even if it's not usable for all of them. 2443 * 2444 * GROUPING_CAN_USE_HASH should be set if it's possible to perform 2445 * hash-based implementations of grouping. 2446 * 2447 * GROUPING_CAN_PARTIAL_AGG should be set if the aggregation is of a type 2448 * for which we support partial aggregation (not, for example, grouping sets). 2449 * It says nothing about parallel-safety or the availability of suitable paths. 2450 */ 2451 #define GROUPING_CAN_USE_SORT 0x0001 2452 #define GROUPING_CAN_USE_HASH 0x0002 2453 #define GROUPING_CAN_PARTIAL_AGG 0x0004 2454 2455 /* 2456 * What kind of partitionwise aggregation is in use? 2457 * 2458 * PARTITIONWISE_AGGREGATE_NONE: Not used. 2459 * 2460 * PARTITIONWISE_AGGREGATE_FULL: Aggregate each partition separately, and 2461 * append the results. 2462 * 2463 * PARTITIONWISE_AGGREGATE_PARTIAL: Partially aggregate each partition 2464 * separately, append the results, and then finalize aggregation. 2465 */ 2466 typedef enum 2467 { 2468 PARTITIONWISE_AGGREGATE_NONE, 2469 PARTITIONWISE_AGGREGATE_FULL, 2470 PARTITIONWISE_AGGREGATE_PARTIAL 2471 } PartitionwiseAggregateType; 2472 2473 /* 2474 * Struct for extra information passed to subroutines of create_grouping_paths 2475 * 2476 * flags indicating what kinds of grouping are possible. 2477 * partial_costs_set is true if the agg_partial_costs and agg_final_costs 2478 * have been initialized. 2479 * agg_partial_costs gives partial aggregation costs. 2480 * agg_final_costs gives finalization costs. 2481 * target_parallel_safe is true if target is parallel safe. 2482 * havingQual gives list of quals to be applied after aggregation. 2483 * targetList gives list of columns to be projected. 2484 * patype is the type of partitionwise aggregation that is being performed. 2485 */ 2486 typedef struct 2487 { 2488 /* Data which remains constant once set. */ 2489 int flags; 2490 bool partial_costs_set; 2491 AggClauseCosts agg_partial_costs; 2492 AggClauseCosts agg_final_costs; 2493 2494 /* Data which may differ across partitions. */ 2495 bool target_parallel_safe; 2496 Node *havingQual; 2497 List *targetList; 2498 PartitionwiseAggregateType patype; 2499 } GroupPathExtraData; 2500 2501 /* 2502 * Struct for extra information passed to subroutines of grouping_planner 2503 * 2504 * limit_needed is true if we actually need a Limit plan node. 2505 * limit_tuples is an estimated bound on the number of output tuples, 2506 * or -1 if no LIMIT or couldn't estimate. 2507 * count_est and offset_est are the estimated values of the LIMIT and OFFSET 2508 * expressions computed by preprocess_limit() (see comments for 2509 * preprocess_limit() for more information). 2510 */ 2511 typedef struct 2512 { 2513 bool limit_needed; 2514 double limit_tuples; 2515 int64 count_est; 2516 int64 offset_est; 2517 } FinalPathExtraData; 2518 2519 /* 2520 * For speed reasons, cost estimation for join paths is performed in two 2521 * phases: the first phase tries to quickly derive a lower bound for the 2522 * join cost, and then we check if that's sufficient to reject the path. 2523 * If not, we come back for a more refined cost estimate. The first phase 2524 * fills a JoinCostWorkspace struct with its preliminary cost estimates 2525 * and possibly additional intermediate values. The second phase takes 2526 * these values as inputs to avoid repeating work. 2527 * 2528 * (Ideally we'd declare this in cost.h, but it's also needed in pathnode.h, 2529 * so seems best to put it here.) 2530 */ 2531 typedef struct JoinCostWorkspace 2532 { 2533 /* Preliminary cost estimates --- must not be larger than final ones! */ 2534 Cost startup_cost; /* cost expended before fetching any tuples */ 2535 Cost total_cost; /* total cost (assuming all tuples fetched) */ 2536 2537 /* Fields below here should be treated as private to costsize.c */ 2538 Cost run_cost; /* non-startup cost components */ 2539 2540 /* private for cost_nestloop code */ 2541 Cost inner_run_cost; /* also used by cost_mergejoin code */ 2542 Cost inner_rescan_run_cost; 2543 2544 /* private for cost_mergejoin code */ 2545 double outer_rows; 2546 double inner_rows; 2547 double outer_skip_rows; 2548 double inner_skip_rows; 2549 2550 /* private for cost_hashjoin code */ 2551 int numbuckets; 2552 int numbatches; 2553 double inner_rows_total; 2554 } JoinCostWorkspace; 2555 2556 #endif /* PATHNODES_H */ 2557