1 /*------------------------------------------------------------------------- 2 * 3 * primnodes.h 4 * Definitions for "primitive" node types, those that are used in more 5 * than one of the parse/plan/execute stages of the query pipeline. 6 * Currently, these are mostly nodes for executable expressions 7 * and join trees. 8 * 9 * 10 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group 11 * Portions Copyright (c) 1994, Regents of the University of California 12 * 13 * src/include/nodes/primnodes.h 14 * 15 *------------------------------------------------------------------------- 16 */ 17 #ifndef PRIMNODES_H 18 #define PRIMNODES_H 19 20 #include "access/attnum.h" 21 #include "nodes/bitmapset.h" 22 #include "nodes/pg_list.h" 23 24 25 /* ---------------------------------------------------------------- 26 * node definitions 27 * ---------------------------------------------------------------- 28 */ 29 30 /* 31 * Alias - 32 * specifies an alias for a range variable; the alias might also 33 * specify renaming of columns within the table. 34 * 35 * Note: colnames is a list of Value nodes (always strings). In Alias structs 36 * associated with RTEs, there may be entries corresponding to dropped 37 * columns; these are normally empty strings (""). See parsenodes.h for info. 38 */ 39 typedef struct Alias 40 { 41 NodeTag type; 42 char *aliasname; /* aliased rel name (never qualified) */ 43 List *colnames; /* optional list of column aliases */ 44 } Alias; 45 46 /* What to do at commit time for temporary relations */ 47 typedef enum OnCommitAction 48 { 49 ONCOMMIT_NOOP, /* No ON COMMIT clause (do nothing) */ 50 ONCOMMIT_PRESERVE_ROWS, /* ON COMMIT PRESERVE ROWS (do nothing) */ 51 ONCOMMIT_DELETE_ROWS, /* ON COMMIT DELETE ROWS */ 52 ONCOMMIT_DROP /* ON COMMIT DROP */ 53 } OnCommitAction; 54 55 /* 56 * RangeVar - range variable, used in FROM clauses 57 * 58 * Also used to represent table names in utility statements; there, the alias 59 * field is not used, and inh tells whether to apply the operation 60 * recursively to child tables. In some contexts it is also useful to carry 61 * a TEMP table indication here. 62 */ 63 typedef struct RangeVar 64 { 65 NodeTag type; 66 char *catalogname; /* the catalog (database) name, or NULL */ 67 char *schemaname; /* the schema name, or NULL */ 68 char *relname; /* the relation/sequence name */ 69 bool inh; /* expand rel by inheritance? recursively act 70 * on children? */ 71 char relpersistence; /* see RELPERSISTENCE_* in pg_class.h */ 72 Alias *alias; /* table alias & optional column aliases */ 73 int location; /* token location, or -1 if unknown */ 74 } RangeVar; 75 76 /* 77 * TableFunc - node for a table function, such as XMLTABLE. 78 * 79 * Entries in the ns_names list are either string Value nodes containing 80 * literal namespace names, or NULL pointers to represent DEFAULT. 81 */ 82 typedef struct TableFunc 83 { 84 NodeTag type; 85 List *ns_uris; /* list of namespace URI expressions */ 86 List *ns_names; /* list of namespace names or NULL */ 87 Node *docexpr; /* input document expression */ 88 Node *rowexpr; /* row filter expression */ 89 List *colnames; /* column names (list of String) */ 90 List *coltypes; /* OID list of column type OIDs */ 91 List *coltypmods; /* integer list of column typmods */ 92 List *colcollations; /* OID list of column collation OIDs */ 93 List *colexprs; /* list of column filter expressions */ 94 List *coldefexprs; /* list of column default expressions */ 95 Bitmapset *notnulls; /* nullability flag for each output column */ 96 int ordinalitycol; /* counts from 0; -1 if none specified */ 97 int location; /* token location, or -1 if unknown */ 98 } TableFunc; 99 100 /* 101 * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and 102 * CREATE MATERIALIZED VIEW 103 * 104 * For CREATE MATERIALIZED VIEW, viewQuery is the parsed-but-not-rewritten 105 * SELECT Query for the view; otherwise it's NULL. (Although it's actually 106 * Query*, we declare it as Node* to avoid a forward reference.) 107 */ 108 typedef struct IntoClause 109 { 110 NodeTag type; 111 112 RangeVar *rel; /* target relation name */ 113 List *colNames; /* column names to assign, or NIL */ 114 char *accessMethod; /* table access method */ 115 List *options; /* options from WITH clause */ 116 OnCommitAction onCommit; /* what do we do at COMMIT? */ 117 char *tableSpaceName; /* table space to use, or NULL */ 118 Node *viewQuery; /* materialized view's SELECT query */ 119 bool skipData; /* true for WITH NO DATA */ 120 } IntoClause; 121 122 123 /* ---------------------------------------------------------------- 124 * node types for executable expressions 125 * ---------------------------------------------------------------- 126 */ 127 128 /* 129 * Expr - generic superclass for executable-expression nodes 130 * 131 * All node types that are used in executable expression trees should derive 132 * from Expr (that is, have Expr as their first field). Since Expr only 133 * contains NodeTag, this is a formality, but it is an easy form of 134 * documentation. See also the ExprState node types in execnodes.h. 135 */ 136 typedef struct Expr 137 { 138 NodeTag type; 139 } Expr; 140 141 /* 142 * Var - expression node representing a variable (ie, a table column) 143 * 144 * In the parser and planner, varno and varattno identify the semantic 145 * referent, which is a base-relation column unless the reference is to a join 146 * USING column that isn't semantically equivalent to either join input column 147 * (because it is a FULL join or the input column requires a type coercion). 148 * In those cases varno and varattno refer to the JOIN RTE. (Early in the 149 * planner, we replace such join references by the implied expression; but up 150 * till then we want join reference Vars to keep their original identity for 151 * query-printing purposes.) 152 * 153 * At the end of planning, Var nodes appearing in upper-level plan nodes are 154 * reassigned to point to the outputs of their subplans; for example, in a 155 * join node varno becomes INNER_VAR or OUTER_VAR and varattno becomes the 156 * index of the proper element of that subplan's target list. Similarly, 157 * INDEX_VAR is used to identify Vars that reference an index column rather 158 * than a heap column. (In ForeignScan and CustomScan plan nodes, INDEX_VAR 159 * is abused to signify references to columns of a custom scan tuple type.) 160 * 161 * In the parser, varnosyn and varattnosyn are either identical to 162 * varno/varattno, or they specify the column's position in an aliased JOIN 163 * RTE that hides the semantic referent RTE's refname. This is a syntactic 164 * identifier as opposed to the semantic identifier; it tells ruleutils.c 165 * how to print the Var properly. varnosyn/varattnosyn retain their values 166 * throughout planning and execution, so they are particularly helpful to 167 * identify Vars when debugging. Note, however, that a Var that is generated 168 * in the planner and doesn't correspond to any simple relation column may 169 * have varnosyn = varattnosyn = 0. 170 */ 171 #define INNER_VAR 65000 /* reference to inner subplan */ 172 #define OUTER_VAR 65001 /* reference to outer subplan */ 173 #define INDEX_VAR 65002 /* reference to index column */ 174 175 #define IS_SPECIAL_VARNO(varno) ((varno) >= INNER_VAR) 176 177 /* Symbols for the indexes of the special RTE entries in rules */ 178 #define PRS2_OLD_VARNO 1 179 #define PRS2_NEW_VARNO 2 180 181 typedef struct Var 182 { 183 Expr xpr; 184 Index varno; /* index of this var's relation in the range 185 * table, or INNER_VAR/OUTER_VAR/INDEX_VAR */ 186 AttrNumber varattno; /* attribute number of this var, or zero for 187 * all attrs ("whole-row Var") */ 188 Oid vartype; /* pg_type OID for the type of this var */ 189 int32 vartypmod; /* pg_attribute typmod value */ 190 Oid varcollid; /* OID of collation, or InvalidOid if none */ 191 Index varlevelsup; /* for subquery variables referencing outer 192 * relations; 0 in a normal var, >0 means N 193 * levels up */ 194 Index varnosyn; /* syntactic relation index (0 if unknown) */ 195 AttrNumber varattnosyn; /* syntactic attribute number */ 196 int location; /* token location, or -1 if unknown */ 197 } Var; 198 199 /* 200 * Const 201 * 202 * Note: for varlena data types, we make a rule that a Const node's value 203 * must be in non-extended form (4-byte header, no compression or external 204 * references). This ensures that the Const node is self-contained and makes 205 * it more likely that equal() will see logically identical values as equal. 206 */ 207 typedef struct Const 208 { 209 Expr xpr; 210 Oid consttype; /* pg_type OID of the constant's datatype */ 211 int32 consttypmod; /* typmod value, if any */ 212 Oid constcollid; /* OID of collation, or InvalidOid if none */ 213 int constlen; /* typlen of the constant's datatype */ 214 Datum constvalue; /* the constant's value */ 215 bool constisnull; /* whether the constant is null (if true, 216 * constvalue is undefined) */ 217 bool constbyval; /* whether this datatype is passed by value. 218 * If true, then all the information is stored 219 * in the Datum. If false, then the Datum 220 * contains a pointer to the information. */ 221 int location; /* token location, or -1 if unknown */ 222 } Const; 223 224 /* 225 * Param 226 * 227 * paramkind specifies the kind of parameter. The possible values 228 * for this field are: 229 * 230 * PARAM_EXTERN: The parameter value is supplied from outside the plan. 231 * Such parameters are numbered from 1 to n. 232 * 233 * PARAM_EXEC: The parameter is an internal executor parameter, used 234 * for passing values into and out of sub-queries or from 235 * nestloop joins to their inner scans. 236 * For historical reasons, such parameters are numbered from 0. 237 * These numbers are independent of PARAM_EXTERN numbers. 238 * 239 * PARAM_SUBLINK: The parameter represents an output column of a SubLink 240 * node's sub-select. The column number is contained in the 241 * `paramid' field. (This type of Param is converted to 242 * PARAM_EXEC during planning.) 243 * 244 * PARAM_MULTIEXPR: Like PARAM_SUBLINK, the parameter represents an 245 * output column of a SubLink node's sub-select, but here, the 246 * SubLink is always a MULTIEXPR SubLink. The high-order 16 bits 247 * of the `paramid' field contain the SubLink's subLinkId, and 248 * the low-order 16 bits contain the column number. (This type 249 * of Param is also converted to PARAM_EXEC during planning.) 250 */ 251 typedef enum ParamKind 252 { 253 PARAM_EXTERN, 254 PARAM_EXEC, 255 PARAM_SUBLINK, 256 PARAM_MULTIEXPR 257 } ParamKind; 258 259 typedef struct Param 260 { 261 Expr xpr; 262 ParamKind paramkind; /* kind of parameter. See above */ 263 int paramid; /* numeric ID for parameter */ 264 Oid paramtype; /* pg_type OID of parameter's datatype */ 265 int32 paramtypmod; /* typmod value, if known */ 266 Oid paramcollid; /* OID of collation, or InvalidOid if none */ 267 int location; /* token location, or -1 if unknown */ 268 } Param; 269 270 /* 271 * Aggref 272 * 273 * The aggregate's args list is a targetlist, ie, a list of TargetEntry nodes. 274 * 275 * For a normal (non-ordered-set) aggregate, the non-resjunk TargetEntries 276 * represent the aggregate's regular arguments (if any) and resjunk TLEs can 277 * be added at the end to represent ORDER BY expressions that are not also 278 * arguments. As in a top-level Query, the TLEs can be marked with 279 * ressortgroupref indexes to let them be referenced by SortGroupClause 280 * entries in the aggorder and/or aggdistinct lists. This represents ORDER BY 281 * and DISTINCT operations to be applied to the aggregate input rows before 282 * they are passed to the transition function. The grammar only allows a 283 * simple "DISTINCT" specifier for the arguments, but we use the full 284 * query-level representation to allow more code sharing. 285 * 286 * For an ordered-set aggregate, the args list represents the WITHIN GROUP 287 * (aggregated) arguments, all of which will be listed in the aggorder list. 288 * DISTINCT is not supported in this case, so aggdistinct will be NIL. 289 * The direct arguments appear in aggdirectargs (as a list of plain 290 * expressions, not TargetEntry nodes). 291 * 292 * aggtranstype is the data type of the state transition values for this 293 * aggregate (resolved to an actual type, if agg's transtype is polymorphic). 294 * This is determined during planning and is InvalidOid before that. 295 * 296 * aggargtypes is an OID list of the data types of the direct and regular 297 * arguments. Normally it's redundant with the aggdirectargs and args lists, 298 * but in a combining aggregate, it's not because the args list has been 299 * replaced with a single argument representing the partial-aggregate 300 * transition values. 301 * 302 * aggsplit indicates the expected partial-aggregation mode for the Aggref's 303 * parent plan node. It's always set to AGGSPLIT_SIMPLE in the parser, but 304 * the planner might change it to something else. We use this mainly as 305 * a crosscheck that the Aggrefs match the plan; but note that when aggsplit 306 * indicates a non-final mode, aggtype reflects the transition data type 307 * not the SQL-level output type of the aggregate. 308 */ 309 typedef struct Aggref 310 { 311 Expr xpr; 312 Oid aggfnoid; /* pg_proc Oid of the aggregate */ 313 Oid aggtype; /* type Oid of result of the aggregate */ 314 Oid aggcollid; /* OID of collation of result */ 315 Oid inputcollid; /* OID of collation that function should use */ 316 Oid aggtranstype; /* type Oid of aggregate's transition value */ 317 List *aggargtypes; /* type Oids of direct and aggregated args */ 318 List *aggdirectargs; /* direct arguments, if an ordered-set agg */ 319 List *args; /* aggregated arguments and sort expressions */ 320 List *aggorder; /* ORDER BY (list of SortGroupClause) */ 321 List *aggdistinct; /* DISTINCT (list of SortGroupClause) */ 322 Expr *aggfilter; /* FILTER expression, if any */ 323 bool aggstar; /* true if argument list was really '*' */ 324 bool aggvariadic; /* true if variadic arguments have been 325 * combined into an array last argument */ 326 char aggkind; /* aggregate kind (see pg_aggregate.h) */ 327 Index agglevelsup; /* > 0 if agg belongs to outer query */ 328 AggSplit aggsplit; /* expected agg-splitting mode of parent Agg */ 329 int location; /* token location, or -1 if unknown */ 330 } Aggref; 331 332 /* 333 * GroupingFunc 334 * 335 * A GroupingFunc is a GROUPING(...) expression, which behaves in many ways 336 * like an aggregate function (e.g. it "belongs" to a specific query level, 337 * which might not be the one immediately containing it), but also differs in 338 * an important respect: it never evaluates its arguments, they merely 339 * designate expressions from the GROUP BY clause of the query level to which 340 * it belongs. 341 * 342 * The spec defines the evaluation of GROUPING() purely by syntactic 343 * replacement, but we make it a real expression for optimization purposes so 344 * that one Agg node can handle multiple grouping sets at once. Evaluating the 345 * result only needs the column positions to check against the grouping set 346 * being projected. However, for EXPLAIN to produce meaningful output, we have 347 * to keep the original expressions around, since expression deparse does not 348 * give us any feasible way to get at the GROUP BY clause. 349 * 350 * Also, we treat two GroupingFunc nodes as equal if they have equal arguments 351 * lists and agglevelsup, without comparing the refs and cols annotations. 352 * 353 * In raw parse output we have only the args list; parse analysis fills in the 354 * refs list, and the planner fills in the cols list. 355 */ 356 typedef struct GroupingFunc 357 { 358 Expr xpr; 359 List *args; /* arguments, not evaluated but kept for 360 * benefit of EXPLAIN etc. */ 361 List *refs; /* ressortgrouprefs of arguments */ 362 List *cols; /* actual column positions set by planner */ 363 Index agglevelsup; /* same as Aggref.agglevelsup */ 364 int location; /* token location */ 365 } GroupingFunc; 366 367 /* 368 * WindowFunc 369 */ 370 typedef struct WindowFunc 371 { 372 Expr xpr; 373 Oid winfnoid; /* pg_proc Oid of the function */ 374 Oid wintype; /* type Oid of result of the window function */ 375 Oid wincollid; /* OID of collation of result */ 376 Oid inputcollid; /* OID of collation that function should use */ 377 List *args; /* arguments to the window function */ 378 Expr *aggfilter; /* FILTER expression, if any */ 379 Index winref; /* index of associated WindowClause */ 380 bool winstar; /* true if argument list was really '*' */ 381 bool winagg; /* is function a simple aggregate? */ 382 int location; /* token location, or -1 if unknown */ 383 } WindowFunc; 384 385 /* ---------------- 386 * SubscriptingRef: describes a subscripting operation over a container 387 * (array, etc). 388 * 389 * A SubscriptingRef can describe fetching a single element from a container, 390 * fetching a part of container (e.g. array slice), storing a single element into 391 * a container, or storing a slice. The "store" cases work with an 392 * initial container value and a source value that is inserted into the 393 * appropriate part of the container; the result of the operation is an 394 * entire new modified container value. 395 * 396 * If reflowerindexpr = NIL, then we are fetching or storing a single container 397 * element at the subscripts given by refupperindexpr. Otherwise we are 398 * fetching or storing a container slice, that is a rectangular subcontainer 399 * with lower and upper bounds given by the index expressions. 400 * reflowerindexpr must be the same length as refupperindexpr when it 401 * is not NIL. 402 * 403 * In the slice case, individual expressions in the subscript lists can be 404 * NULL, meaning "substitute the array's current lower or upper bound". 405 * 406 * Note: the result datatype is the element type when fetching a single 407 * element; but it is the array type when doing subarray fetch or either 408 * type of store. 409 * 410 * Note: for the cases where a container is returned, if refexpr yields a R/W 411 * expanded container, then the implementation is allowed to modify that object 412 * in-place and return the same object.) 413 * ---------------- 414 */ 415 typedef struct SubscriptingRef 416 { 417 Expr xpr; 418 Oid refcontainertype; /* type of the container proper */ 419 Oid refelemtype; /* type of the container elements */ 420 int32 reftypmod; /* typmod of the container (and elements too) */ 421 Oid refcollid; /* OID of collation, or InvalidOid if none */ 422 List *refupperindexpr; /* expressions that evaluate to upper 423 * container indexes */ 424 List *reflowerindexpr; /* expressions that evaluate to lower 425 * container indexes, or NIL for single 426 * container element */ 427 Expr *refexpr; /* the expression that evaluates to a 428 * container value */ 429 430 Expr *refassgnexpr; /* expression for the source value, or NULL if 431 * fetch */ 432 } SubscriptingRef; 433 434 /* 435 * CoercionContext - distinguishes the allowed set of type casts 436 * 437 * NB: ordering of the alternatives is significant; later (larger) values 438 * allow more casts than earlier ones. 439 */ 440 typedef enum CoercionContext 441 { 442 COERCION_IMPLICIT, /* coercion in context of expression */ 443 COERCION_ASSIGNMENT, /* coercion in context of assignment */ 444 COERCION_EXPLICIT /* explicit cast operation */ 445 } CoercionContext; 446 447 /* 448 * CoercionForm - how to display a node that could have come from a cast 449 * 450 * NB: equal() ignores CoercionForm fields, therefore this *must* not carry 451 * any semantically significant information. We need that behavior so that 452 * the planner will consider equivalent implicit and explicit casts to be 453 * equivalent. In cases where those actually behave differently, the coercion 454 * function's arguments will be different. 455 */ 456 typedef enum CoercionForm 457 { 458 COERCE_EXPLICIT_CALL, /* display as a function call */ 459 COERCE_EXPLICIT_CAST, /* display as an explicit cast */ 460 COERCE_IMPLICIT_CAST /* implicit cast, so hide it */ 461 } CoercionForm; 462 463 /* 464 * FuncExpr - expression node for a function call 465 */ 466 typedef struct FuncExpr 467 { 468 Expr xpr; 469 Oid funcid; /* PG_PROC OID of the function */ 470 Oid funcresulttype; /* PG_TYPE OID of result value */ 471 bool funcretset; /* true if function returns set */ 472 bool funcvariadic; /* true if variadic arguments have been 473 * combined into an array last argument */ 474 CoercionForm funcformat; /* how to display this function call */ 475 Oid funccollid; /* OID of collation of result */ 476 Oid inputcollid; /* OID of collation that function should use */ 477 List *args; /* arguments to the function */ 478 int location; /* token location, or -1 if unknown */ 479 } FuncExpr; 480 481 /* 482 * NamedArgExpr - a named argument of a function 483 * 484 * This node type can only appear in the args list of a FuncCall or FuncExpr 485 * node. We support pure positional call notation (no named arguments), 486 * named notation (all arguments are named), and mixed notation (unnamed 487 * arguments followed by named ones). 488 * 489 * Parse analysis sets argnumber to the positional index of the argument, 490 * but doesn't rearrange the argument list. 491 * 492 * The planner will convert argument lists to pure positional notation 493 * during expression preprocessing, so execution never sees a NamedArgExpr. 494 */ 495 typedef struct NamedArgExpr 496 { 497 Expr xpr; 498 Expr *arg; /* the argument expression */ 499 char *name; /* the name */ 500 int argnumber; /* argument's number in positional notation */ 501 int location; /* argument name location, or -1 if unknown */ 502 } NamedArgExpr; 503 504 /* 505 * OpExpr - expression node for an operator invocation 506 * 507 * Semantically, this is essentially the same as a function call. 508 * 509 * Note that opfuncid is not necessarily filled in immediately on creation 510 * of the node. The planner makes sure it is valid before passing the node 511 * tree to the executor, but during parsing/planning opfuncid can be 0. 512 */ 513 typedef struct OpExpr 514 { 515 Expr xpr; 516 Oid opno; /* PG_OPERATOR OID of the operator */ 517 Oid opfuncid; /* PG_PROC OID of underlying function */ 518 Oid opresulttype; /* PG_TYPE OID of result value */ 519 bool opretset; /* true if operator returns set */ 520 Oid opcollid; /* OID of collation of result */ 521 Oid inputcollid; /* OID of collation that operator should use */ 522 List *args; /* arguments to the operator (1 or 2) */ 523 int location; /* token location, or -1 if unknown */ 524 } OpExpr; 525 526 /* 527 * DistinctExpr - expression node for "x IS DISTINCT FROM y" 528 * 529 * Except for the nodetag, this is represented identically to an OpExpr 530 * referencing the "=" operator for x and y. 531 * We use "=", not the more obvious "<>", because more datatypes have "=" 532 * than "<>". This means the executor must invert the operator result. 533 * Note that the operator function won't be called at all if either input 534 * is NULL, since then the result can be determined directly. 535 */ 536 typedef OpExpr DistinctExpr; 537 538 /* 539 * NullIfExpr - a NULLIF expression 540 * 541 * Like DistinctExpr, this is represented the same as an OpExpr referencing 542 * the "=" operator for x and y. 543 */ 544 typedef OpExpr NullIfExpr; 545 546 /* 547 * ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)" 548 * 549 * The operator must yield boolean. It is applied to the left operand 550 * and each element of the righthand array, and the results are combined 551 * with OR or AND (for ANY or ALL respectively). The node representation 552 * is almost the same as for the underlying operator, but we need a useOr 553 * flag to remember whether it's ANY or ALL, and we don't have to store 554 * the result type (or the collation) because it must be boolean. 555 */ 556 typedef struct ScalarArrayOpExpr 557 { 558 Expr xpr; 559 Oid opno; /* PG_OPERATOR OID of the operator */ 560 Oid opfuncid; /* PG_PROC OID of underlying function */ 561 bool useOr; /* true for ANY, false for ALL */ 562 Oid inputcollid; /* OID of collation that operator should use */ 563 List *args; /* the scalar and array operands */ 564 int location; /* token location, or -1 if unknown */ 565 } ScalarArrayOpExpr; 566 567 /* 568 * BoolExpr - expression node for the basic Boolean operators AND, OR, NOT 569 * 570 * Notice the arguments are given as a List. For NOT, of course the list 571 * must always have exactly one element. For AND and OR, there can be two 572 * or more arguments. 573 */ 574 typedef enum BoolExprType 575 { 576 AND_EXPR, OR_EXPR, NOT_EXPR 577 } BoolExprType; 578 579 typedef struct BoolExpr 580 { 581 Expr xpr; 582 BoolExprType boolop; 583 List *args; /* arguments to this expression */ 584 int location; /* token location, or -1 if unknown */ 585 } BoolExpr; 586 587 /* 588 * SubLink 589 * 590 * A SubLink represents a subselect appearing in an expression, and in some 591 * cases also the combining operator(s) just above it. The subLinkType 592 * indicates the form of the expression represented: 593 * EXISTS_SUBLINK EXISTS(SELECT ...) 594 * ALL_SUBLINK (lefthand) op ALL (SELECT ...) 595 * ANY_SUBLINK (lefthand) op ANY (SELECT ...) 596 * ROWCOMPARE_SUBLINK (lefthand) op (SELECT ...) 597 * EXPR_SUBLINK (SELECT with single targetlist item ...) 598 * MULTIEXPR_SUBLINK (SELECT with multiple targetlist items ...) 599 * ARRAY_SUBLINK ARRAY(SELECT with single targetlist item ...) 600 * CTE_SUBLINK WITH query (never actually part of an expression) 601 * For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the 602 * same length as the subselect's targetlist. ROWCOMPARE will *always* have 603 * a list with more than one entry; if the subselect has just one target 604 * then the parser will create an EXPR_SUBLINK instead (and any operator 605 * above the subselect will be represented separately). 606 * ROWCOMPARE, EXPR, and MULTIEXPR require the subselect to deliver at most 607 * one row (if it returns no rows, the result is NULL). 608 * ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean 609 * results. ALL and ANY combine the per-row results using AND and OR 610 * semantics respectively. 611 * ARRAY requires just one target column, and creates an array of the target 612 * column's type using any number of rows resulting from the subselect. 613 * 614 * SubLink is classed as an Expr node, but it is not actually executable; 615 * it must be replaced in the expression tree by a SubPlan node during 616 * planning. 617 * 618 * NOTE: in the raw output of gram.y, testexpr contains just the raw form 619 * of the lefthand expression (if any), and operName is the String name of 620 * the combining operator. Also, subselect is a raw parsetree. During parse 621 * analysis, the parser transforms testexpr into a complete boolean expression 622 * that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the 623 * output columns of the subselect. And subselect is transformed to a Query. 624 * This is the representation seen in saved rules and in the rewriter. 625 * 626 * In EXISTS, EXPR, MULTIEXPR, and ARRAY SubLinks, testexpr and operName 627 * are unused and are always null. 628 * 629 * subLinkId is currently used only for MULTIEXPR SubLinks, and is zero in 630 * other SubLinks. This number identifies different multiple-assignment 631 * subqueries within an UPDATE statement's SET list. It is unique only 632 * within a particular targetlist. The output column(s) of the MULTIEXPR 633 * are referenced by PARAM_MULTIEXPR Params appearing elsewhere in the tlist. 634 * 635 * The CTE_SUBLINK case never occurs in actual SubLink nodes, but it is used 636 * in SubPlans generated for WITH subqueries. 637 */ 638 typedef enum SubLinkType 639 { 640 EXISTS_SUBLINK, 641 ALL_SUBLINK, 642 ANY_SUBLINK, 643 ROWCOMPARE_SUBLINK, 644 EXPR_SUBLINK, 645 MULTIEXPR_SUBLINK, 646 ARRAY_SUBLINK, 647 CTE_SUBLINK /* for SubPlans only */ 648 } SubLinkType; 649 650 651 typedef struct SubLink 652 { 653 Expr xpr; 654 SubLinkType subLinkType; /* see above */ 655 int subLinkId; /* ID (1..n); 0 if not MULTIEXPR */ 656 Node *testexpr; /* outer-query test for ALL/ANY/ROWCOMPARE */ 657 List *operName; /* originally specified operator name */ 658 Node *subselect; /* subselect as Query* or raw parsetree */ 659 int location; /* token location, or -1 if unknown */ 660 } SubLink; 661 662 /* 663 * SubPlan - executable expression node for a subplan (sub-SELECT) 664 * 665 * The planner replaces SubLink nodes in expression trees with SubPlan 666 * nodes after it has finished planning the subquery. SubPlan references 667 * a sub-plantree stored in the subplans list of the toplevel PlannedStmt. 668 * (We avoid a direct link to make it easier to copy expression trees 669 * without causing multiple processing of the subplan.) 670 * 671 * In an ordinary subplan, testexpr points to an executable expression 672 * (OpExpr, an AND/OR tree of OpExprs, or RowCompareExpr) for the combining 673 * operator(s); the left-hand arguments are the original lefthand expressions, 674 * and the right-hand arguments are PARAM_EXEC Param nodes representing the 675 * outputs of the sub-select. (NOTE: runtime coercion functions may be 676 * inserted as well.) This is just the same expression tree as testexpr in 677 * the original SubLink node, but the PARAM_SUBLINK nodes are replaced by 678 * suitably numbered PARAM_EXEC nodes. 679 * 680 * If the sub-select becomes an initplan rather than a subplan, the executable 681 * expression is part of the outer plan's expression tree (and the SubPlan 682 * node itself is not, but rather is found in the outer plan's initPlan 683 * list). In this case testexpr is NULL to avoid duplication. 684 * 685 * The planner also derives lists of the values that need to be passed into 686 * and out of the subplan. Input values are represented as a list "args" of 687 * expressions to be evaluated in the outer-query context (currently these 688 * args are always just Vars, but in principle they could be any expression). 689 * The values are assigned to the global PARAM_EXEC params indexed by parParam 690 * (the parParam and args lists must have the same ordering). setParam is a 691 * list of the PARAM_EXEC params that are computed by the sub-select, if it 692 * is an initplan; they are listed in order by sub-select output column 693 * position. (parParam and setParam are integer Lists, not Bitmapsets, 694 * because their ordering is significant.) 695 * 696 * Also, the planner computes startup and per-call costs for use of the 697 * SubPlan. Note that these include the cost of the subquery proper, 698 * evaluation of the testexpr if any, and any hashtable management overhead. 699 */ 700 typedef struct SubPlan 701 { 702 Expr xpr; 703 /* Fields copied from original SubLink: */ 704 SubLinkType subLinkType; /* see above */ 705 /* The combining operators, transformed to an executable expression: */ 706 Node *testexpr; /* OpExpr or RowCompareExpr expression tree */ 707 List *paramIds; /* IDs of Params embedded in the above */ 708 /* Identification of the Plan tree to use: */ 709 int plan_id; /* Index (from 1) in PlannedStmt.subplans */ 710 /* Identification of the SubPlan for EXPLAIN and debugging purposes: */ 711 char *plan_name; /* A name assigned during planning */ 712 /* Extra data useful for determining subplan's output type: */ 713 Oid firstColType; /* Type of first column of subplan result */ 714 int32 firstColTypmod; /* Typmod of first column of subplan result */ 715 Oid firstColCollation; /* Collation of first column of subplan 716 * result */ 717 /* Information about execution strategy: */ 718 bool useHashTable; /* true to store subselect output in a hash 719 * table (implies we are doing "IN") */ 720 bool unknownEqFalse; /* true if it's okay to return FALSE when the 721 * spec result is UNKNOWN; this allows much 722 * simpler handling of null values */ 723 bool parallel_safe; /* is the subplan parallel-safe? */ 724 /* Note: parallel_safe does not consider contents of testexpr or args */ 725 /* Information for passing params into and out of the subselect: */ 726 /* setParam and parParam are lists of integers (param IDs) */ 727 List *setParam; /* initplan subqueries have to set these 728 * Params for parent plan */ 729 List *parParam; /* indices of input Params from parent plan */ 730 List *args; /* exprs to pass as parParam values */ 731 /* Estimated execution costs: */ 732 Cost startup_cost; /* one-time setup cost */ 733 Cost per_call_cost; /* cost for each subplan evaluation */ 734 } SubPlan; 735 736 /* 737 * AlternativeSubPlan - expression node for a choice among SubPlans 738 * 739 * The subplans are given as a List so that the node definition need not 740 * change if there's ever more than two alternatives. For the moment, 741 * though, there are always exactly two; and the first one is the fast-start 742 * plan. 743 */ 744 typedef struct AlternativeSubPlan 745 { 746 Expr xpr; 747 List *subplans; /* SubPlan(s) with equivalent results */ 748 } AlternativeSubPlan; 749 750 /* ---------------- 751 * FieldSelect 752 * 753 * FieldSelect represents the operation of extracting one field from a tuple 754 * value. At runtime, the input expression is expected to yield a rowtype 755 * Datum. The specified field number is extracted and returned as a Datum. 756 * ---------------- 757 */ 758 759 typedef struct FieldSelect 760 { 761 Expr xpr; 762 Expr *arg; /* input expression */ 763 AttrNumber fieldnum; /* attribute number of field to extract */ 764 Oid resulttype; /* type of the field (result type of this 765 * node) */ 766 int32 resulttypmod; /* output typmod (usually -1) */ 767 Oid resultcollid; /* OID of collation of the field */ 768 } FieldSelect; 769 770 /* ---------------- 771 * FieldStore 772 * 773 * FieldStore represents the operation of modifying one field in a tuple 774 * value, yielding a new tuple value (the input is not touched!). Like 775 * the assign case of SubscriptingRef, this is used to implement UPDATE of a 776 * portion of a column. 777 * 778 * resulttype is always a named composite type (not a domain). To update 779 * a composite domain value, apply CoerceToDomain to the FieldStore. 780 * 781 * A single FieldStore can actually represent updates of several different 782 * fields. The parser only generates FieldStores with single-element lists, 783 * but the planner will collapse multiple updates of the same base column 784 * into one FieldStore. 785 * ---------------- 786 */ 787 788 typedef struct FieldStore 789 { 790 Expr xpr; 791 Expr *arg; /* input tuple value */ 792 List *newvals; /* new value(s) for field(s) */ 793 List *fieldnums; /* integer list of field attnums */ 794 Oid resulttype; /* type of result (same as type of arg) */ 795 /* Like RowExpr, we deliberately omit a typmod and collation here */ 796 } FieldStore; 797 798 /* ---------------- 799 * RelabelType 800 * 801 * RelabelType represents a "dummy" type coercion between two binary- 802 * compatible datatypes, such as reinterpreting the result of an OID 803 * expression as an int4. It is a no-op at runtime; we only need it 804 * to provide a place to store the correct type to be attributed to 805 * the expression result during type resolution. (We can't get away 806 * with just overwriting the type field of the input expression node, 807 * so we need a separate node to show the coercion's result type.) 808 * ---------------- 809 */ 810 811 typedef struct RelabelType 812 { 813 Expr xpr; 814 Expr *arg; /* input expression */ 815 Oid resulttype; /* output type of coercion expression */ 816 int32 resulttypmod; /* output typmod (usually -1) */ 817 Oid resultcollid; /* OID of collation, or InvalidOid if none */ 818 CoercionForm relabelformat; /* how to display this node */ 819 int location; /* token location, or -1 if unknown */ 820 } RelabelType; 821 822 /* ---------------- 823 * CoerceViaIO 824 * 825 * CoerceViaIO represents a type coercion between two types whose textual 826 * representations are compatible, implemented by invoking the source type's 827 * typoutput function then the destination type's typinput function. 828 * ---------------- 829 */ 830 831 typedef struct CoerceViaIO 832 { 833 Expr xpr; 834 Expr *arg; /* input expression */ 835 Oid resulttype; /* output type of coercion */ 836 /* output typmod is not stored, but is presumed -1 */ 837 Oid resultcollid; /* OID of collation, or InvalidOid if none */ 838 CoercionForm coerceformat; /* how to display this node */ 839 int location; /* token location, or -1 if unknown */ 840 } CoerceViaIO; 841 842 /* ---------------- 843 * ArrayCoerceExpr 844 * 845 * ArrayCoerceExpr represents a type coercion from one array type to another, 846 * which is implemented by applying the per-element coercion expression 847 * "elemexpr" to each element of the source array. Within elemexpr, the 848 * source element is represented by a CaseTestExpr node. Note that even if 849 * elemexpr is a no-op (that is, just CaseTestExpr + RelabelType), the 850 * coercion still requires some effort: we have to fix the element type OID 851 * stored in the array header. 852 * ---------------- 853 */ 854 855 typedef struct ArrayCoerceExpr 856 { 857 Expr xpr; 858 Expr *arg; /* input expression (yields an array) */ 859 Expr *elemexpr; /* expression representing per-element work */ 860 Oid resulttype; /* output type of coercion (an array type) */ 861 int32 resulttypmod; /* output typmod (also element typmod) */ 862 Oid resultcollid; /* OID of collation, or InvalidOid if none */ 863 CoercionForm coerceformat; /* how to display this node */ 864 int location; /* token location, or -1 if unknown */ 865 } ArrayCoerceExpr; 866 867 /* ---------------- 868 * ConvertRowtypeExpr 869 * 870 * ConvertRowtypeExpr represents a type coercion from one composite type 871 * to another, where the source type is guaranteed to contain all the columns 872 * needed for the destination type plus possibly others; the columns need not 873 * be in the same positions, but are matched up by name. This is primarily 874 * used to convert a whole-row value of an inheritance child table into a 875 * valid whole-row value of its parent table's rowtype. Both resulttype 876 * and the exposed type of "arg" must be named composite types (not domains). 877 * ---------------- 878 */ 879 880 typedef struct ConvertRowtypeExpr 881 { 882 Expr xpr; 883 Expr *arg; /* input expression */ 884 Oid resulttype; /* output type (always a composite type) */ 885 /* Like RowExpr, we deliberately omit a typmod and collation here */ 886 CoercionForm convertformat; /* how to display this node */ 887 int location; /* token location, or -1 if unknown */ 888 } ConvertRowtypeExpr; 889 890 /*---------- 891 * CollateExpr - COLLATE 892 * 893 * The planner replaces CollateExpr with RelabelType during expression 894 * preprocessing, so execution never sees a CollateExpr. 895 *---------- 896 */ 897 typedef struct CollateExpr 898 { 899 Expr xpr; 900 Expr *arg; /* input expression */ 901 Oid collOid; /* collation's OID */ 902 int location; /* token location, or -1 if unknown */ 903 } CollateExpr; 904 905 /*---------- 906 * CaseExpr - a CASE expression 907 * 908 * We support two distinct forms of CASE expression: 909 * CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ] 910 * CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ] 911 * These are distinguishable by the "arg" field being NULL in the first case 912 * and the testexpr in the second case. 913 * 914 * In the raw grammar output for the second form, the condition expressions 915 * of the WHEN clauses are just the comparison values. Parse analysis 916 * converts these to valid boolean expressions of the form 917 * CaseTestExpr '=' compexpr 918 * where the CaseTestExpr node is a placeholder that emits the correct 919 * value at runtime. This structure is used so that the testexpr need be 920 * evaluated only once. Note that after parse analysis, the condition 921 * expressions always yield boolean. 922 * 923 * Note: we can test whether a CaseExpr has been through parse analysis 924 * yet by checking whether casetype is InvalidOid or not. 925 *---------- 926 */ 927 typedef struct CaseExpr 928 { 929 Expr xpr; 930 Oid casetype; /* type of expression result */ 931 Oid casecollid; /* OID of collation, or InvalidOid if none */ 932 Expr *arg; /* implicit equality comparison argument */ 933 List *args; /* the arguments (list of WHEN clauses) */ 934 Expr *defresult; /* the default result (ELSE clause) */ 935 int location; /* token location, or -1 if unknown */ 936 } CaseExpr; 937 938 /* 939 * CaseWhen - one arm of a CASE expression 940 */ 941 typedef struct CaseWhen 942 { 943 Expr xpr; 944 Expr *expr; /* condition expression */ 945 Expr *result; /* substitution result */ 946 int location; /* token location, or -1 if unknown */ 947 } CaseWhen; 948 949 /* 950 * Placeholder node for the test value to be processed by a CASE expression. 951 * This is effectively like a Param, but can be implemented more simply 952 * since we need only one replacement value at a time. 953 * 954 * We also abuse this node type for some other purposes, including: 955 * * Placeholder for the current array element value in ArrayCoerceExpr; 956 * see build_coercion_expression(). 957 * * Nested FieldStore/SubscriptingRef assignment expressions in INSERT/UPDATE; 958 * see transformAssignmentIndirection(). 959 * 960 * The uses in CaseExpr and ArrayCoerceExpr are safe only to the extent that 961 * there is not any other CaseExpr or ArrayCoerceExpr between the value source 962 * node and its child CaseTestExpr(s). This is true in the parse analysis 963 * output, but the planner's function-inlining logic has to be careful not to 964 * break it. 965 * 966 * The nested-assignment-expression case is safe because the only node types 967 * that can be above such CaseTestExprs are FieldStore and SubscriptingRef. 968 */ 969 typedef struct CaseTestExpr 970 { 971 Expr xpr; 972 Oid typeId; /* type for substituted value */ 973 int32 typeMod; /* typemod for substituted value */ 974 Oid collation; /* collation for the substituted value */ 975 } CaseTestExpr; 976 977 /* 978 * ArrayExpr - an ARRAY[] expression 979 * 980 * Note: if multidims is false, the constituent expressions all yield the 981 * scalar type identified by element_typeid. If multidims is true, the 982 * constituent expressions all yield arrays of element_typeid (ie, the same 983 * type as array_typeid); at runtime we must check for compatible subscripts. 984 */ 985 typedef struct ArrayExpr 986 { 987 Expr xpr; 988 Oid array_typeid; /* type of expression result */ 989 Oid array_collid; /* OID of collation, or InvalidOid if none */ 990 Oid element_typeid; /* common type of array elements */ 991 List *elements; /* the array elements or sub-arrays */ 992 bool multidims; /* true if elements are sub-arrays */ 993 int location; /* token location, or -1 if unknown */ 994 } ArrayExpr; 995 996 /* 997 * RowExpr - a ROW() expression 998 * 999 * Note: the list of fields must have a one-for-one correspondence with 1000 * physical fields of the associated rowtype, although it is okay for it 1001 * to be shorter than the rowtype. That is, the N'th list element must 1002 * match up with the N'th physical field. When the N'th physical field 1003 * is a dropped column (attisdropped) then the N'th list element can just 1004 * be a NULL constant. (This case can only occur for named composite types, 1005 * not RECORD types, since those are built from the RowExpr itself rather 1006 * than vice versa.) It is important not to assume that length(args) is 1007 * the same as the number of columns logically present in the rowtype. 1008 * 1009 * colnames provides field names in cases where the names can't easily be 1010 * obtained otherwise. Names *must* be provided if row_typeid is RECORDOID. 1011 * If row_typeid identifies a known composite type, colnames can be NIL to 1012 * indicate the type's cataloged field names apply. Note that colnames can 1013 * be non-NIL even for a composite type, and typically is when the RowExpr 1014 * was created by expanding a whole-row Var. This is so that we can retain 1015 * the column alias names of the RTE that the Var referenced (which would 1016 * otherwise be very difficult to extract from the parsetree). Like the 1017 * args list, colnames is one-for-one with physical fields of the rowtype. 1018 */ 1019 typedef struct RowExpr 1020 { 1021 Expr xpr; 1022 List *args; /* the fields */ 1023 Oid row_typeid; /* RECORDOID or a composite type's ID */ 1024 1025 /* 1026 * row_typeid cannot be a domain over composite, only plain composite. To 1027 * create a composite domain value, apply CoerceToDomain to the RowExpr. 1028 * 1029 * Note: we deliberately do NOT store a typmod. Although a typmod will be 1030 * associated with specific RECORD types at runtime, it will differ for 1031 * different backends, and so cannot safely be stored in stored 1032 * parsetrees. We must assume typmod -1 for a RowExpr node. 1033 * 1034 * We don't need to store a collation either. The result type is 1035 * necessarily composite, and composite types never have a collation. 1036 */ 1037 CoercionForm row_format; /* how to display this node */ 1038 List *colnames; /* list of String, or NIL */ 1039 int location; /* token location, or -1 if unknown */ 1040 } RowExpr; 1041 1042 /* 1043 * RowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2) 1044 * 1045 * We support row comparison for any operator that can be determined to 1046 * act like =, <>, <, <=, >, or >= (we determine this by looking for the 1047 * operator in btree opfamilies). Note that the same operator name might 1048 * map to a different operator for each pair of row elements, since the 1049 * element datatypes can vary. 1050 * 1051 * A RowCompareExpr node is only generated for the < <= > >= cases; 1052 * the = and <> cases are translated to simple AND or OR combinations 1053 * of the pairwise comparisons. However, we include = and <> in the 1054 * RowCompareType enum for the convenience of parser logic. 1055 */ 1056 typedef enum RowCompareType 1057 { 1058 /* Values of this enum are chosen to match btree strategy numbers */ 1059 ROWCOMPARE_LT = 1, /* BTLessStrategyNumber */ 1060 ROWCOMPARE_LE = 2, /* BTLessEqualStrategyNumber */ 1061 ROWCOMPARE_EQ = 3, /* BTEqualStrategyNumber */ 1062 ROWCOMPARE_GE = 4, /* BTGreaterEqualStrategyNumber */ 1063 ROWCOMPARE_GT = 5, /* BTGreaterStrategyNumber */ 1064 ROWCOMPARE_NE = 6 /* no such btree strategy */ 1065 } RowCompareType; 1066 1067 typedef struct RowCompareExpr 1068 { 1069 Expr xpr; 1070 RowCompareType rctype; /* LT LE GE or GT, never EQ or NE */ 1071 List *opnos; /* OID list of pairwise comparison ops */ 1072 List *opfamilies; /* OID list of containing operator families */ 1073 List *inputcollids; /* OID list of collations for comparisons */ 1074 List *largs; /* the left-hand input arguments */ 1075 List *rargs; /* the right-hand input arguments */ 1076 } RowCompareExpr; 1077 1078 /* 1079 * CoalesceExpr - a COALESCE expression 1080 */ 1081 typedef struct CoalesceExpr 1082 { 1083 Expr xpr; 1084 Oid coalescetype; /* type of expression result */ 1085 Oid coalescecollid; /* OID of collation, or InvalidOid if none */ 1086 List *args; /* the arguments */ 1087 int location; /* token location, or -1 if unknown */ 1088 } CoalesceExpr; 1089 1090 /* 1091 * MinMaxExpr - a GREATEST or LEAST function 1092 */ 1093 typedef enum MinMaxOp 1094 { 1095 IS_GREATEST, 1096 IS_LEAST 1097 } MinMaxOp; 1098 1099 typedef struct MinMaxExpr 1100 { 1101 Expr xpr; 1102 Oid minmaxtype; /* common type of arguments and result */ 1103 Oid minmaxcollid; /* OID of collation of result */ 1104 Oid inputcollid; /* OID of collation that function should use */ 1105 MinMaxOp op; /* function to execute */ 1106 List *args; /* the arguments */ 1107 int location; /* token location, or -1 if unknown */ 1108 } MinMaxExpr; 1109 1110 /* 1111 * SQLValueFunction - parameterless functions with special grammar productions 1112 * 1113 * The SQL standard categorizes some of these as <datetime value function> 1114 * and others as <general value specification>. We call 'em SQLValueFunctions 1115 * for lack of a better term. We store type and typmod of the result so that 1116 * some code doesn't need to know each function individually, and because 1117 * we would need to store typmod anyway for some of the datetime functions. 1118 * Note that currently, all variants return non-collating datatypes, so we do 1119 * not need a collation field; also, all these functions are stable. 1120 */ 1121 typedef enum SQLValueFunctionOp 1122 { 1123 SVFOP_CURRENT_DATE, 1124 SVFOP_CURRENT_TIME, 1125 SVFOP_CURRENT_TIME_N, 1126 SVFOP_CURRENT_TIMESTAMP, 1127 SVFOP_CURRENT_TIMESTAMP_N, 1128 SVFOP_LOCALTIME, 1129 SVFOP_LOCALTIME_N, 1130 SVFOP_LOCALTIMESTAMP, 1131 SVFOP_LOCALTIMESTAMP_N, 1132 SVFOP_CURRENT_ROLE, 1133 SVFOP_CURRENT_USER, 1134 SVFOP_USER, 1135 SVFOP_SESSION_USER, 1136 SVFOP_CURRENT_CATALOG, 1137 SVFOP_CURRENT_SCHEMA 1138 } SQLValueFunctionOp; 1139 1140 typedef struct SQLValueFunction 1141 { 1142 Expr xpr; 1143 SQLValueFunctionOp op; /* which function this is */ 1144 Oid type; /* result type/typmod */ 1145 int32 typmod; 1146 int location; /* token location, or -1 if unknown */ 1147 } SQLValueFunction; 1148 1149 /* 1150 * XmlExpr - various SQL/XML functions requiring special grammar productions 1151 * 1152 * 'name' carries the "NAME foo" argument (already XML-escaped). 1153 * 'named_args' and 'arg_names' represent an xml_attribute list. 1154 * 'args' carries all other arguments. 1155 * 1156 * Note: result type/typmod/collation are not stored, but can be deduced 1157 * from the XmlExprOp. The type/typmod fields are just used for display 1158 * purposes, and are NOT necessarily the true result type of the node. 1159 */ 1160 typedef enum XmlExprOp 1161 { 1162 IS_XMLCONCAT, /* XMLCONCAT(args) */ 1163 IS_XMLELEMENT, /* XMLELEMENT(name, xml_attributes, args) */ 1164 IS_XMLFOREST, /* XMLFOREST(xml_attributes) */ 1165 IS_XMLPARSE, /* XMLPARSE(text, is_doc, preserve_ws) */ 1166 IS_XMLPI, /* XMLPI(name [, args]) */ 1167 IS_XMLROOT, /* XMLROOT(xml, version, standalone) */ 1168 IS_XMLSERIALIZE, /* XMLSERIALIZE(is_document, xmlval) */ 1169 IS_DOCUMENT /* xmlval IS DOCUMENT */ 1170 } XmlExprOp; 1171 1172 typedef enum 1173 { 1174 XMLOPTION_DOCUMENT, 1175 XMLOPTION_CONTENT 1176 } XmlOptionType; 1177 1178 typedef struct XmlExpr 1179 { 1180 Expr xpr; 1181 XmlExprOp op; /* xml function ID */ 1182 char *name; /* name in xml(NAME foo ...) syntaxes */ 1183 List *named_args; /* non-XML expressions for xml_attributes */ 1184 List *arg_names; /* parallel list of Value strings */ 1185 List *args; /* list of expressions */ 1186 XmlOptionType xmloption; /* DOCUMENT or CONTENT */ 1187 Oid type; /* target type/typmod for XMLSERIALIZE */ 1188 int32 typmod; 1189 int location; /* token location, or -1 if unknown */ 1190 } XmlExpr; 1191 1192 /* ---------------- 1193 * NullTest 1194 * 1195 * NullTest represents the operation of testing a value for NULLness. 1196 * The appropriate test is performed and returned as a boolean Datum. 1197 * 1198 * When argisrow is false, this simply represents a test for the null value. 1199 * 1200 * When argisrow is true, the input expression must yield a rowtype, and 1201 * the node implements "row IS [NOT] NULL" per the SQL standard. This 1202 * includes checking individual fields for NULLness when the row datum 1203 * itself isn't NULL. 1204 * 1205 * NOTE: the combination of a rowtype input and argisrow==false does NOT 1206 * correspond to the SQL notation "row IS [NOT] NULL"; instead, this case 1207 * represents the SQL notation "row IS [NOT] DISTINCT FROM NULL". 1208 * ---------------- 1209 */ 1210 1211 typedef enum NullTestType 1212 { 1213 IS_NULL, IS_NOT_NULL 1214 } NullTestType; 1215 1216 typedef struct NullTest 1217 { 1218 Expr xpr; 1219 Expr *arg; /* input expression */ 1220 NullTestType nulltesttype; /* IS NULL, IS NOT NULL */ 1221 bool argisrow; /* T to perform field-by-field null checks */ 1222 int location; /* token location, or -1 if unknown */ 1223 } NullTest; 1224 1225 /* 1226 * BooleanTest 1227 * 1228 * BooleanTest represents the operation of determining whether a boolean 1229 * is TRUE, FALSE, or UNKNOWN (ie, NULL). All six meaningful combinations 1230 * are supported. Note that a NULL input does *not* cause a NULL result. 1231 * The appropriate test is performed and returned as a boolean Datum. 1232 */ 1233 1234 typedef enum BoolTestType 1235 { 1236 IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN 1237 } BoolTestType; 1238 1239 typedef struct BooleanTest 1240 { 1241 Expr xpr; 1242 Expr *arg; /* input expression */ 1243 BoolTestType booltesttype; /* test type */ 1244 int location; /* token location, or -1 if unknown */ 1245 } BooleanTest; 1246 1247 /* 1248 * CoerceToDomain 1249 * 1250 * CoerceToDomain represents the operation of coercing a value to a domain 1251 * type. At runtime (and not before) the precise set of constraints to be 1252 * checked will be determined. If the value passes, it is returned as the 1253 * result; if not, an error is raised. Note that this is equivalent to 1254 * RelabelType in the scenario where no constraints are applied. 1255 */ 1256 typedef struct CoerceToDomain 1257 { 1258 Expr xpr; 1259 Expr *arg; /* input expression */ 1260 Oid resulttype; /* domain type ID (result type) */ 1261 int32 resulttypmod; /* output typmod (currently always -1) */ 1262 Oid resultcollid; /* OID of collation, or InvalidOid if none */ 1263 CoercionForm coercionformat; /* how to display this node */ 1264 int location; /* token location, or -1 if unknown */ 1265 } CoerceToDomain; 1266 1267 /* 1268 * Placeholder node for the value to be processed by a domain's check 1269 * constraint. This is effectively like a Param, but can be implemented more 1270 * simply since we need only one replacement value at a time. 1271 * 1272 * Note: the typeId/typeMod/collation will be set from the domain's base type, 1273 * not the domain itself. This is because we shouldn't consider the value 1274 * to be a member of the domain if we haven't yet checked its constraints. 1275 */ 1276 typedef struct CoerceToDomainValue 1277 { 1278 Expr xpr; 1279 Oid typeId; /* type for substituted value */ 1280 int32 typeMod; /* typemod for substituted value */ 1281 Oid collation; /* collation for the substituted value */ 1282 int location; /* token location, or -1 if unknown */ 1283 } CoerceToDomainValue; 1284 1285 /* 1286 * Placeholder node for a DEFAULT marker in an INSERT or UPDATE command. 1287 * 1288 * This is not an executable expression: it must be replaced by the actual 1289 * column default expression during rewriting. But it is convenient to 1290 * treat it as an expression node during parsing and rewriting. 1291 */ 1292 typedef struct SetToDefault 1293 { 1294 Expr xpr; 1295 Oid typeId; /* type for substituted value */ 1296 int32 typeMod; /* typemod for substituted value */ 1297 Oid collation; /* collation for the substituted value */ 1298 int location; /* token location, or -1 if unknown */ 1299 } SetToDefault; 1300 1301 /* 1302 * Node representing [WHERE] CURRENT OF cursor_name 1303 * 1304 * CURRENT OF is a bit like a Var, in that it carries the rangetable index 1305 * of the target relation being constrained; this aids placing the expression 1306 * correctly during planning. We can assume however that its "levelsup" is 1307 * always zero, due to the syntactic constraints on where it can appear. 1308 * 1309 * The referenced cursor can be represented either as a hardwired string 1310 * or as a reference to a run-time parameter of type REFCURSOR. The latter 1311 * case is for the convenience of plpgsql. 1312 */ 1313 typedef struct CurrentOfExpr 1314 { 1315 Expr xpr; 1316 Index cvarno; /* RT index of target relation */ 1317 char *cursor_name; /* name of referenced cursor, or NULL */ 1318 int cursor_param; /* refcursor parameter number, or 0 */ 1319 } CurrentOfExpr; 1320 1321 /* 1322 * NextValueExpr - get next value from sequence 1323 * 1324 * This has the same effect as calling the nextval() function, but it does not 1325 * check permissions on the sequence. This is used for identity columns, 1326 * where the sequence is an implicit dependency without its own permissions. 1327 */ 1328 typedef struct NextValueExpr 1329 { 1330 Expr xpr; 1331 Oid seqid; 1332 Oid typeId; 1333 } NextValueExpr; 1334 1335 /* 1336 * InferenceElem - an element of a unique index inference specification 1337 * 1338 * This mostly matches the structure of IndexElems, but having a dedicated 1339 * primnode allows for a clean separation between the use of index parameters 1340 * by utility commands, and this node. 1341 */ 1342 typedef struct InferenceElem 1343 { 1344 Expr xpr; 1345 Node *expr; /* expression to infer from, or NULL */ 1346 Oid infercollid; /* OID of collation, or InvalidOid */ 1347 Oid inferopclass; /* OID of att opclass, or InvalidOid */ 1348 } InferenceElem; 1349 1350 /*-------------------- 1351 * TargetEntry - 1352 * a target entry (used in query target lists) 1353 * 1354 * Strictly speaking, a TargetEntry isn't an expression node (since it can't 1355 * be evaluated by ExecEvalExpr). But we treat it as one anyway, since in 1356 * very many places it's convenient to process a whole query targetlist as a 1357 * single expression tree. 1358 * 1359 * In a SELECT's targetlist, resno should always be equal to the item's 1360 * ordinal position (counting from 1). However, in an INSERT or UPDATE 1361 * targetlist, resno represents the attribute number of the destination 1362 * column for the item; so there may be missing or out-of-order resnos. 1363 * It is even legal to have duplicated resnos; consider 1364 * UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ... 1365 * The two meanings come together in the executor, because the planner 1366 * transforms INSERT/UPDATE tlists into a normalized form with exactly 1367 * one entry for each column of the destination table. Before that's 1368 * happened, however, it is risky to assume that resno == position. 1369 * Generally get_tle_by_resno() should be used rather than list_nth() 1370 * to fetch tlist entries by resno, and only in SELECT should you assume 1371 * that resno is a unique identifier. 1372 * 1373 * resname is required to represent the correct column name in non-resjunk 1374 * entries of top-level SELECT targetlists, since it will be used as the 1375 * column title sent to the frontend. In most other contexts it is only 1376 * a debugging aid, and may be wrong or even NULL. (In particular, it may 1377 * be wrong in a tlist from a stored rule, if the referenced column has been 1378 * renamed by ALTER TABLE since the rule was made. Also, the planner tends 1379 * to store NULL rather than look up a valid name for tlist entries in 1380 * non-toplevel plan nodes.) In resjunk entries, resname should be either 1381 * a specific system-generated name (such as "ctid") or NULL; anything else 1382 * risks confusing ExecGetJunkAttribute! 1383 * 1384 * ressortgroupref is used in the representation of ORDER BY, GROUP BY, and 1385 * DISTINCT items. Targetlist entries with ressortgroupref=0 are not 1386 * sort/group items. If ressortgroupref>0, then this item is an ORDER BY, 1387 * GROUP BY, and/or DISTINCT target value. No two entries in a targetlist 1388 * may have the same nonzero ressortgroupref --- but there is no particular 1389 * meaning to the nonzero values, except as tags. (For example, one must 1390 * not assume that lower ressortgroupref means a more significant sort key.) 1391 * The order of the associated SortGroupClause lists determine the semantics. 1392 * 1393 * resorigtbl/resorigcol identify the source of the column, if it is a 1394 * simple reference to a column of a base table (or view). If it is not 1395 * a simple reference, these fields are zeroes. 1396 * 1397 * If resjunk is true then the column is a working column (such as a sort key) 1398 * that should be removed from the final output of the query. Resjunk columns 1399 * must have resnos that cannot duplicate any regular column's resno. Also 1400 * note that there are places that assume resjunk columns come after non-junk 1401 * columns. 1402 *-------------------- 1403 */ 1404 typedef struct TargetEntry 1405 { 1406 Expr xpr; 1407 Expr *expr; /* expression to evaluate */ 1408 AttrNumber resno; /* attribute number (see notes above) */ 1409 char *resname; /* name of the column (could be NULL) */ 1410 Index ressortgroupref; /* nonzero if referenced by a sort/group 1411 * clause */ 1412 Oid resorigtbl; /* OID of column's source table */ 1413 AttrNumber resorigcol; /* column's number in source table */ 1414 bool resjunk; /* set to true to eliminate the attribute from 1415 * final target list */ 1416 } TargetEntry; 1417 1418 1419 /* ---------------------------------------------------------------- 1420 * node types for join trees 1421 * 1422 * The leaves of a join tree structure are RangeTblRef nodes. Above 1423 * these, JoinExpr nodes can appear to denote a specific kind of join 1424 * or qualified join. Also, FromExpr nodes can appear to denote an 1425 * ordinary cross-product join ("FROM foo, bar, baz WHERE ..."). 1426 * FromExpr is like a JoinExpr of jointype JOIN_INNER, except that it 1427 * may have any number of child nodes, not just two. 1428 * 1429 * NOTE: the top level of a Query's jointree is always a FromExpr. 1430 * Even if the jointree contains no rels, there will be a FromExpr. 1431 * 1432 * NOTE: the qualification expressions present in JoinExpr nodes are 1433 * *in addition to* the query's main WHERE clause, which appears as the 1434 * qual of the top-level FromExpr. The reason for associating quals with 1435 * specific nodes in the jointree is that the position of a qual is critical 1436 * when outer joins are present. (If we enforce a qual too soon or too late, 1437 * that may cause the outer join to produce the wrong set of NULL-extended 1438 * rows.) If all joins are inner joins then all the qual positions are 1439 * semantically interchangeable. 1440 * 1441 * NOTE: in the raw output of gram.y, a join tree contains RangeVar, 1442 * RangeSubselect, and RangeFunction nodes, which are all replaced by 1443 * RangeTblRef nodes during the parse analysis phase. Also, the top-level 1444 * FromExpr is added during parse analysis; the grammar regards FROM and 1445 * WHERE as separate. 1446 * ---------------------------------------------------------------- 1447 */ 1448 1449 /* 1450 * RangeTblRef - reference to an entry in the query's rangetable 1451 * 1452 * We could use direct pointers to the RT entries and skip having these 1453 * nodes, but multiple pointers to the same node in a querytree cause 1454 * lots of headaches, so it seems better to store an index into the RT. 1455 */ 1456 typedef struct RangeTblRef 1457 { 1458 NodeTag type; 1459 int rtindex; 1460 } RangeTblRef; 1461 1462 /*---------- 1463 * JoinExpr - for SQL JOIN expressions 1464 * 1465 * isNatural, usingClause, and quals are interdependent. The user can write 1466 * only one of NATURAL, USING(), or ON() (this is enforced by the grammar). 1467 * If he writes NATURAL then parse analysis generates the equivalent USING() 1468 * list, and from that fills in "quals" with the right equality comparisons. 1469 * If he writes USING() then "quals" is filled with equality comparisons. 1470 * If he writes ON() then only "quals" is set. Note that NATURAL/USING 1471 * are not equivalent to ON() since they also affect the output column list. 1472 * 1473 * alias is an Alias node representing the AS alias-clause attached to the 1474 * join expression, or NULL if no clause. NB: presence or absence of the 1475 * alias has a critical impact on semantics, because a join with an alias 1476 * restricts visibility of the tables/columns inside it. 1477 * 1478 * During parse analysis, an RTE is created for the Join, and its index 1479 * is filled into rtindex. This RTE is present mainly so that Vars can 1480 * be created that refer to the outputs of the join. The planner sometimes 1481 * generates JoinExprs internally; these can have rtindex = 0 if there are 1482 * no join alias variables referencing such joins. 1483 *---------- 1484 */ 1485 typedef struct JoinExpr 1486 { 1487 NodeTag type; 1488 JoinType jointype; /* type of join */ 1489 bool isNatural; /* Natural join? Will need to shape table */ 1490 Node *larg; /* left subtree */ 1491 Node *rarg; /* right subtree */ 1492 List *usingClause; /* USING clause, if any (list of String) */ 1493 Node *quals; /* qualifiers on join, if any */ 1494 Alias *alias; /* user-written alias clause, if any */ 1495 int rtindex; /* RT index assigned for join, or 0 */ 1496 } JoinExpr; 1497 1498 /*---------- 1499 * FromExpr - represents a FROM ... WHERE ... construct 1500 * 1501 * This is both more flexible than a JoinExpr (it can have any number of 1502 * children, including zero) and less so --- we don't need to deal with 1503 * aliases and so on. The output column set is implicitly just the union 1504 * of the outputs of the children. 1505 *---------- 1506 */ 1507 typedef struct FromExpr 1508 { 1509 NodeTag type; 1510 List *fromlist; /* List of join subtrees */ 1511 Node *quals; /* qualifiers on join, if any */ 1512 } FromExpr; 1513 1514 /*---------- 1515 * OnConflictExpr - represents an ON CONFLICT DO ... expression 1516 * 1517 * The optimizer requires a list of inference elements, and optionally a WHERE 1518 * clause to infer a unique index. The unique index (or, occasionally, 1519 * indexes) inferred are used to arbitrate whether or not the alternative ON 1520 * CONFLICT path is taken. 1521 *---------- 1522 */ 1523 typedef struct OnConflictExpr 1524 { 1525 NodeTag type; 1526 OnConflictAction action; /* DO NOTHING or UPDATE? */ 1527 1528 /* Arbiter */ 1529 List *arbiterElems; /* unique index arbiter list (of 1530 * InferenceElem's) */ 1531 Node *arbiterWhere; /* unique index arbiter WHERE clause */ 1532 Oid constraint; /* pg_constraint OID for arbiter */ 1533 1534 /* ON CONFLICT UPDATE */ 1535 List *onConflictSet; /* List of ON CONFLICT SET TargetEntrys */ 1536 Node *onConflictWhere; /* qualifiers to restrict UPDATE to */ 1537 int exclRelIndex; /* RT index of 'excluded' relation */ 1538 List *exclRelTlist; /* tlist of the EXCLUDED pseudo relation */ 1539 } OnConflictExpr; 1540 1541 #endif /* PRIMNODES_H */ 1542