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) 1996-2018, 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 List *options; /* options from WITH clause */ 115 OnCommitAction onCommit; /* what do we do at COMMIT? */ 116 char *tableSpaceName; /* table space to use, or NULL */ 117 Node *viewQuery; /* materialized view's SELECT query */ 118 bool skipData; /* true for WITH NO DATA */ 119 } IntoClause; 120 121 122 /* ---------------------------------------------------------------- 123 * node types for executable expressions 124 * ---------------------------------------------------------------- 125 */ 126 127 /* 128 * Expr - generic superclass for executable-expression nodes 129 * 130 * All node types that are used in executable expression trees should derive 131 * from Expr (that is, have Expr as their first field). Since Expr only 132 * contains NodeTag, this is a formality, but it is an easy form of 133 * documentation. See also the ExprState node types in execnodes.h. 134 */ 135 typedef struct Expr 136 { 137 NodeTag type; 138 } Expr; 139 140 /* 141 * Var - expression node representing a variable (ie, a table column) 142 * 143 * Note: during parsing/planning, varnoold/varoattno are always just copies 144 * of varno/varattno. At the tail end of planning, Var nodes appearing in 145 * upper-level plan nodes are reassigned to point to the outputs of their 146 * subplans; for example, in a join node varno becomes INNER_VAR or OUTER_VAR 147 * and varattno becomes the index of the proper element of that subplan's 148 * target list. Similarly, INDEX_VAR is used to identify Vars that reference 149 * an index column rather than a heap column. (In ForeignScan and CustomScan 150 * plan nodes, INDEX_VAR is abused to signify references to columns of a 151 * custom scan tuple type.) In all these cases, varnoold/varoattno hold the 152 * original values. The code doesn't really need varnoold/varoattno, but they 153 * are very useful for debugging and interpreting completed plans, so we keep 154 * them around. 155 */ 156 #define INNER_VAR 65000 /* reference to inner subplan */ 157 #define OUTER_VAR 65001 /* reference to outer subplan */ 158 #define INDEX_VAR 65002 /* reference to index column */ 159 160 #define IS_SPECIAL_VARNO(varno) ((varno) >= INNER_VAR) 161 162 /* Symbols for the indexes of the special RTE entries in rules */ 163 #define PRS2_OLD_VARNO 1 164 #define PRS2_NEW_VARNO 2 165 166 typedef struct Var 167 { 168 Expr xpr; 169 Index varno; /* index of this var's relation in the range 170 * table, or INNER_VAR/OUTER_VAR/INDEX_VAR */ 171 AttrNumber varattno; /* attribute number of this var, or zero for 172 * all attrs ("whole-row Var") */ 173 Oid vartype; /* pg_type OID for the type of this var */ 174 int32 vartypmod; /* pg_attribute typmod value */ 175 Oid varcollid; /* OID of collation, or InvalidOid if none */ 176 Index varlevelsup; /* for subquery variables referencing outer 177 * relations; 0 in a normal var, >0 means N 178 * levels up */ 179 Index varnoold; /* original value of varno, for debugging */ 180 AttrNumber varoattno; /* original value of varattno */ 181 int location; /* token location, or -1 if unknown */ 182 } Var; 183 184 /* 185 * Const 186 * 187 * Note: for varlena data types, we make a rule that a Const node's value 188 * must be in non-extended form (4-byte header, no compression or external 189 * references). This ensures that the Const node is self-contained and makes 190 * it more likely that equal() will see logically identical values as equal. 191 */ 192 typedef struct Const 193 { 194 Expr xpr; 195 Oid consttype; /* pg_type OID of the constant's datatype */ 196 int32 consttypmod; /* typmod value, if any */ 197 Oid constcollid; /* OID of collation, or InvalidOid if none */ 198 int constlen; /* typlen of the constant's datatype */ 199 Datum constvalue; /* the constant's value */ 200 bool constisnull; /* whether the constant is null (if true, 201 * constvalue is undefined) */ 202 bool constbyval; /* whether this datatype is passed by value. 203 * If true, then all the information is stored 204 * in the Datum. If false, then the Datum 205 * contains a pointer to the information. */ 206 int location; /* token location, or -1 if unknown */ 207 } Const; 208 209 /* 210 * Param 211 * 212 * paramkind specifies the kind of parameter. The possible values 213 * for this field are: 214 * 215 * PARAM_EXTERN: The parameter value is supplied from outside the plan. 216 * Such parameters are numbered from 1 to n. 217 * 218 * PARAM_EXEC: The parameter is an internal executor parameter, used 219 * for passing values into and out of sub-queries or from 220 * nestloop joins to their inner scans. 221 * For historical reasons, such parameters are numbered from 0. 222 * These numbers are independent of PARAM_EXTERN numbers. 223 * 224 * PARAM_SUBLINK: The parameter represents an output column of a SubLink 225 * node's sub-select. The column number is contained in the 226 * `paramid' field. (This type of Param is converted to 227 * PARAM_EXEC during planning.) 228 * 229 * PARAM_MULTIEXPR: Like PARAM_SUBLINK, the parameter represents an 230 * output column of a SubLink node's sub-select, but here, the 231 * SubLink is always a MULTIEXPR SubLink. The high-order 16 bits 232 * of the `paramid' field contain the SubLink's subLinkId, and 233 * the low-order 16 bits contain the column number. (This type 234 * of Param is also converted to PARAM_EXEC during planning.) 235 */ 236 typedef enum ParamKind 237 { 238 PARAM_EXTERN, 239 PARAM_EXEC, 240 PARAM_SUBLINK, 241 PARAM_MULTIEXPR 242 } ParamKind; 243 244 typedef struct Param 245 { 246 Expr xpr; 247 ParamKind paramkind; /* kind of parameter. See above */ 248 int paramid; /* numeric ID for parameter */ 249 Oid paramtype; /* pg_type OID of parameter's datatype */ 250 int32 paramtypmod; /* typmod value, if known */ 251 Oid paramcollid; /* OID of collation, or InvalidOid if none */ 252 int location; /* token location, or -1 if unknown */ 253 } Param; 254 255 /* 256 * Aggref 257 * 258 * The aggregate's args list is a targetlist, ie, a list of TargetEntry nodes. 259 * 260 * For a normal (non-ordered-set) aggregate, the non-resjunk TargetEntries 261 * represent the aggregate's regular arguments (if any) and resjunk TLEs can 262 * be added at the end to represent ORDER BY expressions that are not also 263 * arguments. As in a top-level Query, the TLEs can be marked with 264 * ressortgroupref indexes to let them be referenced by SortGroupClause 265 * entries in the aggorder and/or aggdistinct lists. This represents ORDER BY 266 * and DISTINCT operations to be applied to the aggregate input rows before 267 * they are passed to the transition function. The grammar only allows a 268 * simple "DISTINCT" specifier for the arguments, but we use the full 269 * query-level representation to allow more code sharing. 270 * 271 * For an ordered-set aggregate, the args list represents the WITHIN GROUP 272 * (aggregated) arguments, all of which will be listed in the aggorder list. 273 * DISTINCT is not supported in this case, so aggdistinct will be NIL. 274 * The direct arguments appear in aggdirectargs (as a list of plain 275 * expressions, not TargetEntry nodes). 276 * 277 * aggtranstype is the data type of the state transition values for this 278 * aggregate (resolved to an actual type, if agg's transtype is polymorphic). 279 * This is determined during planning and is InvalidOid before that. 280 * 281 * aggargtypes is an OID list of the data types of the direct and regular 282 * arguments. Normally it's redundant with the aggdirectargs and args lists, 283 * but in a combining aggregate, it's not because the args list has been 284 * replaced with a single argument representing the partial-aggregate 285 * transition values. 286 * 287 * aggsplit indicates the expected partial-aggregation mode for the Aggref's 288 * parent plan node. It's always set to AGGSPLIT_SIMPLE in the parser, but 289 * the planner might change it to something else. We use this mainly as 290 * a crosscheck that the Aggrefs match the plan; but note that when aggsplit 291 * indicates a non-final mode, aggtype reflects the transition data type 292 * not the SQL-level output type of the aggregate. 293 */ 294 typedef struct Aggref 295 { 296 Expr xpr; 297 Oid aggfnoid; /* pg_proc Oid of the aggregate */ 298 Oid aggtype; /* type Oid of result of the aggregate */ 299 Oid aggcollid; /* OID of collation of result */ 300 Oid inputcollid; /* OID of collation that function should use */ 301 Oid aggtranstype; /* type Oid of aggregate's transition value */ 302 List *aggargtypes; /* type Oids of direct and aggregated args */ 303 List *aggdirectargs; /* direct arguments, if an ordered-set agg */ 304 List *args; /* aggregated arguments and sort expressions */ 305 List *aggorder; /* ORDER BY (list of SortGroupClause) */ 306 List *aggdistinct; /* DISTINCT (list of SortGroupClause) */ 307 Expr *aggfilter; /* FILTER expression, if any */ 308 bool aggstar; /* true if argument list was really '*' */ 309 bool aggvariadic; /* true if variadic arguments have been 310 * combined into an array last argument */ 311 char aggkind; /* aggregate kind (see pg_aggregate.h) */ 312 Index agglevelsup; /* > 0 if agg belongs to outer query */ 313 AggSplit aggsplit; /* expected agg-splitting mode of parent Agg */ 314 int location; /* token location, or -1 if unknown */ 315 } Aggref; 316 317 /* 318 * GroupingFunc 319 * 320 * A GroupingFunc is a GROUPING(...) expression, which behaves in many ways 321 * like an aggregate function (e.g. it "belongs" to a specific query level, 322 * which might not be the one immediately containing it), but also differs in 323 * an important respect: it never evaluates its arguments, they merely 324 * designate expressions from the GROUP BY clause of the query level to which 325 * it belongs. 326 * 327 * The spec defines the evaluation of GROUPING() purely by syntactic 328 * replacement, but we make it a real expression for optimization purposes so 329 * that one Agg node can handle multiple grouping sets at once. Evaluating the 330 * result only needs the column positions to check against the grouping set 331 * being projected. However, for EXPLAIN to produce meaningful output, we have 332 * to keep the original expressions around, since expression deparse does not 333 * give us any feasible way to get at the GROUP BY clause. 334 * 335 * Also, we treat two GroupingFunc nodes as equal if they have equal arguments 336 * lists and agglevelsup, without comparing the refs and cols annotations. 337 * 338 * In raw parse output we have only the args list; parse analysis fills in the 339 * refs list, and the planner fills in the cols list. 340 */ 341 typedef struct GroupingFunc 342 { 343 Expr xpr; 344 List *args; /* arguments, not evaluated but kept for 345 * benefit of EXPLAIN etc. */ 346 List *refs; /* ressortgrouprefs of arguments */ 347 List *cols; /* actual column positions set by planner */ 348 Index agglevelsup; /* same as Aggref.agglevelsup */ 349 int location; /* token location */ 350 } GroupingFunc; 351 352 /* 353 * WindowFunc 354 */ 355 typedef struct WindowFunc 356 { 357 Expr xpr; 358 Oid winfnoid; /* pg_proc Oid of the function */ 359 Oid wintype; /* type Oid of result of the window function */ 360 Oid wincollid; /* OID of collation of result */ 361 Oid inputcollid; /* OID of collation that function should use */ 362 List *args; /* arguments to the window function */ 363 Expr *aggfilter; /* FILTER expression, if any */ 364 Index winref; /* index of associated WindowClause */ 365 bool winstar; /* true if argument list was really '*' */ 366 bool winagg; /* is function a simple aggregate? */ 367 int location; /* token location, or -1 if unknown */ 368 } WindowFunc; 369 370 /* ---------------- 371 * ArrayRef: describes an array subscripting operation 372 * 373 * An ArrayRef can describe fetching a single element from an array, 374 * fetching a subarray (array slice), storing a single element into 375 * an array, or storing a slice. The "store" cases work with an 376 * initial array value and a source value that is inserted into the 377 * appropriate part of the array; the result of the operation is an 378 * entire new modified array value. 379 * 380 * If reflowerindexpr = NIL, then we are fetching or storing a single array 381 * element at the subscripts given by refupperindexpr. Otherwise we are 382 * fetching or storing an array slice, that is a rectangular subarray 383 * with lower and upper bounds given by the index expressions. 384 * reflowerindexpr must be the same length as refupperindexpr when it 385 * is not NIL. 386 * 387 * In the slice case, individual expressions in the subscript lists can be 388 * NULL, meaning "substitute the array's current lower or upper bound". 389 * 390 * Note: the result datatype is the element type when fetching a single 391 * element; but it is the array type when doing subarray fetch or either 392 * type of store. 393 * 394 * Note: for the cases where an array is returned, if refexpr yields a R/W 395 * expanded array, then the implementation is allowed to modify that object 396 * in-place and return the same object.) 397 * ---------------- 398 */ 399 typedef struct ArrayRef 400 { 401 Expr xpr; 402 Oid refarraytype; /* type of the array proper */ 403 Oid refelemtype; /* type of the array elements */ 404 int32 reftypmod; /* typmod of the array (and elements too) */ 405 Oid refcollid; /* OID of collation, or InvalidOid if none */ 406 List *refupperindexpr; /* expressions that evaluate to upper 407 * array indexes */ 408 List *reflowerindexpr; /* expressions that evaluate to lower 409 * array indexes, or NIL for single array 410 * element */ 411 Expr *refexpr; /* the expression that evaluates to an array 412 * value */ 413 Expr *refassgnexpr; /* expression for the source value, or NULL if 414 * fetch */ 415 } ArrayRef; 416 417 /* 418 * CoercionContext - distinguishes the allowed set of type casts 419 * 420 * NB: ordering of the alternatives is significant; later (larger) values 421 * allow more casts than earlier ones. 422 */ 423 typedef enum CoercionContext 424 { 425 COERCION_IMPLICIT, /* coercion in context of expression */ 426 COERCION_ASSIGNMENT, /* coercion in context of assignment */ 427 COERCION_EXPLICIT /* explicit cast operation */ 428 } CoercionContext; 429 430 /* 431 * CoercionForm - how to display a node that could have come from a cast 432 * 433 * NB: equal() ignores CoercionForm fields, therefore this *must* not carry 434 * any semantically significant information. We need that behavior so that 435 * the planner will consider equivalent implicit and explicit casts to be 436 * equivalent. In cases where those actually behave differently, the coercion 437 * function's arguments will be different. 438 */ 439 typedef enum CoercionForm 440 { 441 COERCE_EXPLICIT_CALL, /* display as a function call */ 442 COERCE_EXPLICIT_CAST, /* display as an explicit cast */ 443 COERCE_IMPLICIT_CAST /* implicit cast, so hide it */ 444 } CoercionForm; 445 446 /* 447 * FuncExpr - expression node for a function call 448 */ 449 typedef struct FuncExpr 450 { 451 Expr xpr; 452 Oid funcid; /* PG_PROC OID of the function */ 453 Oid funcresulttype; /* PG_TYPE OID of result value */ 454 bool funcretset; /* true if function returns set */ 455 bool funcvariadic; /* true if variadic arguments have been 456 * combined into an array last argument */ 457 CoercionForm funcformat; /* how to display this function call */ 458 Oid funccollid; /* OID of collation of result */ 459 Oid inputcollid; /* OID of collation that function should use */ 460 List *args; /* arguments to the function */ 461 int location; /* token location, or -1 if unknown */ 462 } FuncExpr; 463 464 /* 465 * NamedArgExpr - a named argument of a function 466 * 467 * This node type can only appear in the args list of a FuncCall or FuncExpr 468 * node. We support pure positional call notation (no named arguments), 469 * named notation (all arguments are named), and mixed notation (unnamed 470 * arguments followed by named ones). 471 * 472 * Parse analysis sets argnumber to the positional index of the argument, 473 * but doesn't rearrange the argument list. 474 * 475 * The planner will convert argument lists to pure positional notation 476 * during expression preprocessing, so execution never sees a NamedArgExpr. 477 */ 478 typedef struct NamedArgExpr 479 { 480 Expr xpr; 481 Expr *arg; /* the argument expression */ 482 char *name; /* the name */ 483 int argnumber; /* argument's number in positional notation */ 484 int location; /* argument name location, or -1 if unknown */ 485 } NamedArgExpr; 486 487 /* 488 * OpExpr - expression node for an operator invocation 489 * 490 * Semantically, this is essentially the same as a function call. 491 * 492 * Note that opfuncid is not necessarily filled in immediately on creation 493 * of the node. The planner makes sure it is valid before passing the node 494 * tree to the executor, but during parsing/planning opfuncid can be 0. 495 */ 496 typedef struct OpExpr 497 { 498 Expr xpr; 499 Oid opno; /* PG_OPERATOR OID of the operator */ 500 Oid opfuncid; /* PG_PROC OID of underlying function */ 501 Oid opresulttype; /* PG_TYPE OID of result value */ 502 bool opretset; /* true if operator returns set */ 503 Oid opcollid; /* OID of collation of result */ 504 Oid inputcollid; /* OID of collation that operator should use */ 505 List *args; /* arguments to the operator (1 or 2) */ 506 int location; /* token location, or -1 if unknown */ 507 } OpExpr; 508 509 /* 510 * DistinctExpr - expression node for "x IS DISTINCT FROM y" 511 * 512 * Except for the nodetag, this is represented identically to an OpExpr 513 * referencing the "=" operator for x and y. 514 * We use "=", not the more obvious "<>", because more datatypes have "=" 515 * than "<>". This means the executor must invert the operator result. 516 * Note that the operator function won't be called at all if either input 517 * is NULL, since then the result can be determined directly. 518 */ 519 typedef OpExpr DistinctExpr; 520 521 /* 522 * NullIfExpr - a NULLIF expression 523 * 524 * Like DistinctExpr, this is represented the same as an OpExpr referencing 525 * the "=" operator for x and y. 526 */ 527 typedef OpExpr NullIfExpr; 528 529 /* 530 * ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)" 531 * 532 * The operator must yield boolean. It is applied to the left operand 533 * and each element of the righthand array, and the results are combined 534 * with OR or AND (for ANY or ALL respectively). The node representation 535 * is almost the same as for the underlying operator, but we need a useOr 536 * flag to remember whether it's ANY or ALL, and we don't have to store 537 * the result type (or the collation) because it must be boolean. 538 */ 539 typedef struct ScalarArrayOpExpr 540 { 541 Expr xpr; 542 Oid opno; /* PG_OPERATOR OID of the operator */ 543 Oid opfuncid; /* PG_PROC OID of underlying function */ 544 bool useOr; /* true for ANY, false for ALL */ 545 Oid inputcollid; /* OID of collation that operator should use */ 546 List *args; /* the scalar and array operands */ 547 int location; /* token location, or -1 if unknown */ 548 } ScalarArrayOpExpr; 549 550 /* 551 * BoolExpr - expression node for the basic Boolean operators AND, OR, NOT 552 * 553 * Notice the arguments are given as a List. For NOT, of course the list 554 * must always have exactly one element. For AND and OR, there can be two 555 * or more arguments. 556 */ 557 typedef enum BoolExprType 558 { 559 AND_EXPR, OR_EXPR, NOT_EXPR 560 } BoolExprType; 561 562 typedef struct BoolExpr 563 { 564 Expr xpr; 565 BoolExprType boolop; 566 List *args; /* arguments to this expression */ 567 int location; /* token location, or -1 if unknown */ 568 } BoolExpr; 569 570 /* 571 * SubLink 572 * 573 * A SubLink represents a subselect appearing in an expression, and in some 574 * cases also the combining operator(s) just above it. The subLinkType 575 * indicates the form of the expression represented: 576 * EXISTS_SUBLINK EXISTS(SELECT ...) 577 * ALL_SUBLINK (lefthand) op ALL (SELECT ...) 578 * ANY_SUBLINK (lefthand) op ANY (SELECT ...) 579 * ROWCOMPARE_SUBLINK (lefthand) op (SELECT ...) 580 * EXPR_SUBLINK (SELECT with single targetlist item ...) 581 * MULTIEXPR_SUBLINK (SELECT with multiple targetlist items ...) 582 * ARRAY_SUBLINK ARRAY(SELECT with single targetlist item ...) 583 * CTE_SUBLINK WITH query (never actually part of an expression) 584 * For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the 585 * same length as the subselect's targetlist. ROWCOMPARE will *always* have 586 * a list with more than one entry; if the subselect has just one target 587 * then the parser will create an EXPR_SUBLINK instead (and any operator 588 * above the subselect will be represented separately). 589 * ROWCOMPARE, EXPR, and MULTIEXPR require the subselect to deliver at most 590 * one row (if it returns no rows, the result is NULL). 591 * ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean 592 * results. ALL and ANY combine the per-row results using AND and OR 593 * semantics respectively. 594 * ARRAY requires just one target column, and creates an array of the target 595 * column's type using any number of rows resulting from the subselect. 596 * 597 * SubLink is classed as an Expr node, but it is not actually executable; 598 * it must be replaced in the expression tree by a SubPlan node during 599 * planning. 600 * 601 * NOTE: in the raw output of gram.y, testexpr contains just the raw form 602 * of the lefthand expression (if any), and operName is the String name of 603 * the combining operator. Also, subselect is a raw parsetree. During parse 604 * analysis, the parser transforms testexpr into a complete boolean expression 605 * that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the 606 * output columns of the subselect. And subselect is transformed to a Query. 607 * This is the representation seen in saved rules and in the rewriter. 608 * 609 * In EXISTS, EXPR, MULTIEXPR, and ARRAY SubLinks, testexpr and operName 610 * are unused and are always null. 611 * 612 * subLinkId is currently used only for MULTIEXPR SubLinks, and is zero in 613 * other SubLinks. This number identifies different multiple-assignment 614 * subqueries within an UPDATE statement's SET list. It is unique only 615 * within a particular targetlist. The output column(s) of the MULTIEXPR 616 * are referenced by PARAM_MULTIEXPR Params appearing elsewhere in the tlist. 617 * 618 * The CTE_SUBLINK case never occurs in actual SubLink nodes, but it is used 619 * in SubPlans generated for WITH subqueries. 620 */ 621 typedef enum SubLinkType 622 { 623 EXISTS_SUBLINK, 624 ALL_SUBLINK, 625 ANY_SUBLINK, 626 ROWCOMPARE_SUBLINK, 627 EXPR_SUBLINK, 628 MULTIEXPR_SUBLINK, 629 ARRAY_SUBLINK, 630 CTE_SUBLINK /* for SubPlans only */ 631 } SubLinkType; 632 633 634 typedef struct SubLink 635 { 636 Expr xpr; 637 SubLinkType subLinkType; /* see above */ 638 int subLinkId; /* ID (1..n); 0 if not MULTIEXPR */ 639 Node *testexpr; /* outer-query test for ALL/ANY/ROWCOMPARE */ 640 List *operName; /* originally specified operator name */ 641 Node *subselect; /* subselect as Query* or raw parsetree */ 642 int location; /* token location, or -1 if unknown */ 643 } SubLink; 644 645 /* 646 * SubPlan - executable expression node for a subplan (sub-SELECT) 647 * 648 * The planner replaces SubLink nodes in expression trees with SubPlan 649 * nodes after it has finished planning the subquery. SubPlan references 650 * a sub-plantree stored in the subplans list of the toplevel PlannedStmt. 651 * (We avoid a direct link to make it easier to copy expression trees 652 * without causing multiple processing of the subplan.) 653 * 654 * In an ordinary subplan, testexpr points to an executable expression 655 * (OpExpr, an AND/OR tree of OpExprs, or RowCompareExpr) for the combining 656 * operator(s); the left-hand arguments are the original lefthand expressions, 657 * and the right-hand arguments are PARAM_EXEC Param nodes representing the 658 * outputs of the sub-select. (NOTE: runtime coercion functions may be 659 * inserted as well.) This is just the same expression tree as testexpr in 660 * the original SubLink node, but the PARAM_SUBLINK nodes are replaced by 661 * suitably numbered PARAM_EXEC nodes. 662 * 663 * If the sub-select becomes an initplan rather than a subplan, the executable 664 * expression is part of the outer plan's expression tree (and the SubPlan 665 * node itself is not, but rather is found in the outer plan's initPlan 666 * list). In this case testexpr is NULL to avoid duplication. 667 * 668 * The planner also derives lists of the values that need to be passed into 669 * and out of the subplan. Input values are represented as a list "args" of 670 * expressions to be evaluated in the outer-query context (currently these 671 * args are always just Vars, but in principle they could be any expression). 672 * The values are assigned to the global PARAM_EXEC params indexed by parParam 673 * (the parParam and args lists must have the same ordering). setParam is a 674 * list of the PARAM_EXEC params that are computed by the sub-select, if it 675 * is an initplan; they are listed in order by sub-select output column 676 * position. (parParam and setParam are integer Lists, not Bitmapsets, 677 * because their ordering is significant.) 678 * 679 * Also, the planner computes startup and per-call costs for use of the 680 * SubPlan. Note that these include the cost of the subquery proper, 681 * evaluation of the testexpr if any, and any hashtable management overhead. 682 */ 683 typedef struct SubPlan 684 { 685 Expr xpr; 686 /* Fields copied from original SubLink: */ 687 SubLinkType subLinkType; /* see above */ 688 /* The combining operators, transformed to an executable expression: */ 689 Node *testexpr; /* OpExpr or RowCompareExpr expression tree */ 690 List *paramIds; /* IDs of Params embedded in the above */ 691 /* Identification of the Plan tree to use: */ 692 int plan_id; /* Index (from 1) in PlannedStmt.subplans */ 693 /* Identification of the SubPlan for EXPLAIN and debugging purposes: */ 694 char *plan_name; /* A name assigned during planning */ 695 /* Extra data useful for determining subplan's output type: */ 696 Oid firstColType; /* Type of first column of subplan result */ 697 int32 firstColTypmod; /* Typmod of first column of subplan result */ 698 Oid firstColCollation; /* Collation of first column of subplan 699 * result */ 700 /* Information about execution strategy: */ 701 bool useHashTable; /* true to store subselect output in a hash 702 * table (implies we are doing "IN") */ 703 bool unknownEqFalse; /* true if it's okay to return FALSE when the 704 * spec result is UNKNOWN; this allows much 705 * simpler handling of null values */ 706 bool parallel_safe; /* is the subplan parallel-safe? */ 707 /* Note: parallel_safe does not consider contents of testexpr or args */ 708 /* Information for passing params into and out of the subselect: */ 709 /* setParam and parParam are lists of integers (param IDs) */ 710 List *setParam; /* initplan subqueries have to set these 711 * Params for parent plan */ 712 List *parParam; /* indices of input Params from parent plan */ 713 List *args; /* exprs to pass as parParam values */ 714 /* Estimated execution costs: */ 715 Cost startup_cost; /* one-time setup cost */ 716 Cost per_call_cost; /* cost for each subplan evaluation */ 717 } SubPlan; 718 719 /* 720 * AlternativeSubPlan - expression node for a choice among SubPlans 721 * 722 * The subplans are given as a List so that the node definition need not 723 * change if there's ever more than two alternatives. For the moment, 724 * though, there are always exactly two; and the first one is the fast-start 725 * plan. 726 */ 727 typedef struct AlternativeSubPlan 728 { 729 Expr xpr; 730 List *subplans; /* SubPlan(s) with equivalent results */ 731 } AlternativeSubPlan; 732 733 /* ---------------- 734 * FieldSelect 735 * 736 * FieldSelect represents the operation of extracting one field from a tuple 737 * value. At runtime, the input expression is expected to yield a rowtype 738 * Datum. The specified field number is extracted and returned as a Datum. 739 * ---------------- 740 */ 741 742 typedef struct FieldSelect 743 { 744 Expr xpr; 745 Expr *arg; /* input expression */ 746 AttrNumber fieldnum; /* attribute number of field to extract */ 747 Oid resulttype; /* type of the field (result type of this 748 * node) */ 749 int32 resulttypmod; /* output typmod (usually -1) */ 750 Oid resultcollid; /* OID of collation of the field */ 751 } FieldSelect; 752 753 /* ---------------- 754 * FieldStore 755 * 756 * FieldStore represents the operation of modifying one field in a tuple 757 * value, yielding a new tuple value (the input is not touched!). Like 758 * the assign case of ArrayRef, this is used to implement UPDATE of a 759 * portion of a column. 760 * 761 * resulttype is always a named composite type (not a domain). To update 762 * a composite domain value, apply CoerceToDomain to the FieldStore. 763 * 764 * A single FieldStore can actually represent updates of several different 765 * fields. The parser only generates FieldStores with single-element lists, 766 * but the planner will collapse multiple updates of the same base column 767 * into one FieldStore. 768 * ---------------- 769 */ 770 771 typedef struct FieldStore 772 { 773 Expr xpr; 774 Expr *arg; /* input tuple value */ 775 List *newvals; /* new value(s) for field(s) */ 776 List *fieldnums; /* integer list of field attnums */ 777 Oid resulttype; /* type of result (same as type of arg) */ 778 /* Like RowExpr, we deliberately omit a typmod and collation here */ 779 } FieldStore; 780 781 /* ---------------- 782 * RelabelType 783 * 784 * RelabelType represents a "dummy" type coercion between two binary- 785 * compatible datatypes, such as reinterpreting the result of an OID 786 * expression as an int4. It is a no-op at runtime; we only need it 787 * to provide a place to store the correct type to be attributed to 788 * the expression result during type resolution. (We can't get away 789 * with just overwriting the type field of the input expression node, 790 * so we need a separate node to show the coercion's result type.) 791 * ---------------- 792 */ 793 794 typedef struct RelabelType 795 { 796 Expr xpr; 797 Expr *arg; /* input expression */ 798 Oid resulttype; /* output type of coercion expression */ 799 int32 resulttypmod; /* output typmod (usually -1) */ 800 Oid resultcollid; /* OID of collation, or InvalidOid if none */ 801 CoercionForm relabelformat; /* how to display this node */ 802 int location; /* token location, or -1 if unknown */ 803 } RelabelType; 804 805 /* ---------------- 806 * CoerceViaIO 807 * 808 * CoerceViaIO represents a type coercion between two types whose textual 809 * representations are compatible, implemented by invoking the source type's 810 * typoutput function then the destination type's typinput function. 811 * ---------------- 812 */ 813 814 typedef struct CoerceViaIO 815 { 816 Expr xpr; 817 Expr *arg; /* input expression */ 818 Oid resulttype; /* output type of coercion */ 819 /* output typmod is not stored, but is presumed -1 */ 820 Oid resultcollid; /* OID of collation, or InvalidOid if none */ 821 CoercionForm coerceformat; /* how to display this node */ 822 int location; /* token location, or -1 if unknown */ 823 } CoerceViaIO; 824 825 /* ---------------- 826 * ArrayCoerceExpr 827 * 828 * ArrayCoerceExpr represents a type coercion from one array type to another, 829 * which is implemented by applying the per-element coercion expression 830 * "elemexpr" to each element of the source array. Within elemexpr, the 831 * source element is represented by a CaseTestExpr node. Note that even if 832 * elemexpr is a no-op (that is, just CaseTestExpr + RelabelType), the 833 * coercion still requires some effort: we have to fix the element type OID 834 * stored in the array header. 835 * ---------------- 836 */ 837 838 typedef struct ArrayCoerceExpr 839 { 840 Expr xpr; 841 Expr *arg; /* input expression (yields an array) */ 842 Expr *elemexpr; /* expression representing per-element work */ 843 Oid resulttype; /* output type of coercion (an array type) */ 844 int32 resulttypmod; /* output typmod (also element typmod) */ 845 Oid resultcollid; /* OID of collation, or InvalidOid if none */ 846 CoercionForm coerceformat; /* how to display this node */ 847 int location; /* token location, or -1 if unknown */ 848 } ArrayCoerceExpr; 849 850 /* ---------------- 851 * ConvertRowtypeExpr 852 * 853 * ConvertRowtypeExpr represents a type coercion from one composite type 854 * to another, where the source type is guaranteed to contain all the columns 855 * needed for the destination type plus possibly others; the columns need not 856 * be in the same positions, but are matched up by name. This is primarily 857 * used to convert a whole-row value of an inheritance child table into a 858 * valid whole-row value of its parent table's rowtype. Both resulttype 859 * and the exposed type of "arg" must be named composite types (not domains). 860 * ---------------- 861 */ 862 863 typedef struct ConvertRowtypeExpr 864 { 865 Expr xpr; 866 Expr *arg; /* input expression */ 867 Oid resulttype; /* output type (always a composite type) */ 868 /* Like RowExpr, we deliberately omit a typmod and collation here */ 869 CoercionForm convertformat; /* how to display this node */ 870 int location; /* token location, or -1 if unknown */ 871 } ConvertRowtypeExpr; 872 873 /*---------- 874 * CollateExpr - COLLATE 875 * 876 * The planner replaces CollateExpr with RelabelType during expression 877 * preprocessing, so execution never sees a CollateExpr. 878 *---------- 879 */ 880 typedef struct CollateExpr 881 { 882 Expr xpr; 883 Expr *arg; /* input expression */ 884 Oid collOid; /* collation's OID */ 885 int location; /* token location, or -1 if unknown */ 886 } CollateExpr; 887 888 /*---------- 889 * CaseExpr - a CASE expression 890 * 891 * We support two distinct forms of CASE expression: 892 * CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ] 893 * CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ] 894 * These are distinguishable by the "arg" field being NULL in the first case 895 * and the testexpr in the second case. 896 * 897 * In the raw grammar output for the second form, the condition expressions 898 * of the WHEN clauses are just the comparison values. Parse analysis 899 * converts these to valid boolean expressions of the form 900 * CaseTestExpr '=' compexpr 901 * where the CaseTestExpr node is a placeholder that emits the correct 902 * value at runtime. This structure is used so that the testexpr need be 903 * evaluated only once. Note that after parse analysis, the condition 904 * expressions always yield boolean. 905 * 906 * Note: we can test whether a CaseExpr has been through parse analysis 907 * yet by checking whether casetype is InvalidOid or not. 908 *---------- 909 */ 910 typedef struct CaseExpr 911 { 912 Expr xpr; 913 Oid casetype; /* type of expression result */ 914 Oid casecollid; /* OID of collation, or InvalidOid if none */ 915 Expr *arg; /* implicit equality comparison argument */ 916 List *args; /* the arguments (list of WHEN clauses) */ 917 Expr *defresult; /* the default result (ELSE clause) */ 918 int location; /* token location, or -1 if unknown */ 919 } CaseExpr; 920 921 /* 922 * CaseWhen - one arm of a CASE expression 923 */ 924 typedef struct CaseWhen 925 { 926 Expr xpr; 927 Expr *expr; /* condition expression */ 928 Expr *result; /* substitution result */ 929 int location; /* token location, or -1 if unknown */ 930 } CaseWhen; 931 932 /* 933 * Placeholder node for the test value to be processed by a CASE expression. 934 * This is effectively like a Param, but can be implemented more simply 935 * since we need only one replacement value at a time. 936 * 937 * We also abuse this node type for some other purposes, including: 938 * * Placeholder for the current array element value in ArrayCoerceExpr; 939 * see build_coercion_expression(). 940 * * Nested FieldStore/ArrayRef assignment expressions in INSERT/UPDATE; 941 * see transformAssignmentIndirection(). 942 * 943 * The uses in CaseExpr and ArrayCoerceExpr are safe only to the extent that 944 * there is not any other CaseExpr or ArrayCoerceExpr between the value source 945 * node and its child CaseTestExpr(s). This is true in the parse analysis 946 * output, but the planner's function-inlining logic has to be careful not to 947 * break it. 948 * 949 * The nested-assignment-expression case is safe because the only node types 950 * that can be above such CaseTestExprs are FieldStore and ArrayRef. 951 */ 952 typedef struct CaseTestExpr 953 { 954 Expr xpr; 955 Oid typeId; /* type for substituted value */ 956 int32 typeMod; /* typemod for substituted value */ 957 Oid collation; /* collation for the substituted value */ 958 } CaseTestExpr; 959 960 /* 961 * ArrayExpr - an ARRAY[] expression 962 * 963 * Note: if multidims is false, the constituent expressions all yield the 964 * scalar type identified by element_typeid. If multidims is true, the 965 * constituent expressions all yield arrays of element_typeid (ie, the same 966 * type as array_typeid); at runtime we must check for compatible subscripts. 967 */ 968 typedef struct ArrayExpr 969 { 970 Expr xpr; 971 Oid array_typeid; /* type of expression result */ 972 Oid array_collid; /* OID of collation, or InvalidOid if none */ 973 Oid element_typeid; /* common type of array elements */ 974 List *elements; /* the array elements or sub-arrays */ 975 bool multidims; /* true if elements are sub-arrays */ 976 int location; /* token location, or -1 if unknown */ 977 } ArrayExpr; 978 979 /* 980 * RowExpr - a ROW() expression 981 * 982 * Note: the list of fields must have a one-for-one correspondence with 983 * physical fields of the associated rowtype, although it is okay for it 984 * to be shorter than the rowtype. That is, the N'th list element must 985 * match up with the N'th physical field. When the N'th physical field 986 * is a dropped column (attisdropped) then the N'th list element can just 987 * be a NULL constant. (This case can only occur for named composite types, 988 * not RECORD types, since those are built from the RowExpr itself rather 989 * than vice versa.) It is important not to assume that length(args) is 990 * the same as the number of columns logically present in the rowtype. 991 * 992 * colnames provides field names in cases where the names can't easily be 993 * obtained otherwise. Names *must* be provided if row_typeid is RECORDOID. 994 * If row_typeid identifies a known composite type, colnames can be NIL to 995 * indicate the type's cataloged field names apply. Note that colnames can 996 * be non-NIL even for a composite type, and typically is when the RowExpr 997 * was created by expanding a whole-row Var. This is so that we can retain 998 * the column alias names of the RTE that the Var referenced (which would 999 * otherwise be very difficult to extract from the parsetree). Like the 1000 * args list, colnames is one-for-one with physical fields of the rowtype. 1001 */ 1002 typedef struct RowExpr 1003 { 1004 Expr xpr; 1005 List *args; /* the fields */ 1006 Oid row_typeid; /* RECORDOID or a composite type's ID */ 1007 1008 /* 1009 * row_typeid cannot be a domain over composite, only plain composite. To 1010 * create a composite domain value, apply CoerceToDomain to the RowExpr. 1011 * 1012 * Note: we deliberately do NOT store a typmod. Although a typmod will be 1013 * associated with specific RECORD types at runtime, it will differ for 1014 * different backends, and so cannot safely be stored in stored 1015 * parsetrees. We must assume typmod -1 for a RowExpr node. 1016 * 1017 * We don't need to store a collation either. The result type is 1018 * necessarily composite, and composite types never have a collation. 1019 */ 1020 CoercionForm row_format; /* how to display this node */ 1021 List *colnames; /* list of String, or NIL */ 1022 int location; /* token location, or -1 if unknown */ 1023 } RowExpr; 1024 1025 /* 1026 * RowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2) 1027 * 1028 * We support row comparison for any operator that can be determined to 1029 * act like =, <>, <, <=, >, or >= (we determine this by looking for the 1030 * operator in btree opfamilies). Note that the same operator name might 1031 * map to a different operator for each pair of row elements, since the 1032 * element datatypes can vary. 1033 * 1034 * A RowCompareExpr node is only generated for the < <= > >= cases; 1035 * the = and <> cases are translated to simple AND or OR combinations 1036 * of the pairwise comparisons. However, we include = and <> in the 1037 * RowCompareType enum for the convenience of parser logic. 1038 */ 1039 typedef enum RowCompareType 1040 { 1041 /* Values of this enum are chosen to match btree strategy numbers */ 1042 ROWCOMPARE_LT = 1, /* BTLessStrategyNumber */ 1043 ROWCOMPARE_LE = 2, /* BTLessEqualStrategyNumber */ 1044 ROWCOMPARE_EQ = 3, /* BTEqualStrategyNumber */ 1045 ROWCOMPARE_GE = 4, /* BTGreaterEqualStrategyNumber */ 1046 ROWCOMPARE_GT = 5, /* BTGreaterStrategyNumber */ 1047 ROWCOMPARE_NE = 6 /* no such btree strategy */ 1048 } RowCompareType; 1049 1050 typedef struct RowCompareExpr 1051 { 1052 Expr xpr; 1053 RowCompareType rctype; /* LT LE GE or GT, never EQ or NE */ 1054 List *opnos; /* OID list of pairwise comparison ops */ 1055 List *opfamilies; /* OID list of containing operator families */ 1056 List *inputcollids; /* OID list of collations for comparisons */ 1057 List *largs; /* the left-hand input arguments */ 1058 List *rargs; /* the right-hand input arguments */ 1059 } RowCompareExpr; 1060 1061 /* 1062 * CoalesceExpr - a COALESCE expression 1063 */ 1064 typedef struct CoalesceExpr 1065 { 1066 Expr xpr; 1067 Oid coalescetype; /* type of expression result */ 1068 Oid coalescecollid; /* OID of collation, or InvalidOid if none */ 1069 List *args; /* the arguments */ 1070 int location; /* token location, or -1 if unknown */ 1071 } CoalesceExpr; 1072 1073 /* 1074 * MinMaxExpr - a GREATEST or LEAST function 1075 */ 1076 typedef enum MinMaxOp 1077 { 1078 IS_GREATEST, 1079 IS_LEAST 1080 } MinMaxOp; 1081 1082 typedef struct MinMaxExpr 1083 { 1084 Expr xpr; 1085 Oid minmaxtype; /* common type of arguments and result */ 1086 Oid minmaxcollid; /* OID of collation of result */ 1087 Oid inputcollid; /* OID of collation that function should use */ 1088 MinMaxOp op; /* function to execute */ 1089 List *args; /* the arguments */ 1090 int location; /* token location, or -1 if unknown */ 1091 } MinMaxExpr; 1092 1093 /* 1094 * SQLValueFunction - parameterless functions with special grammar productions 1095 * 1096 * The SQL standard categorizes some of these as <datetime value function> 1097 * and others as <general value specification>. We call 'em SQLValueFunctions 1098 * for lack of a better term. We store type and typmod of the result so that 1099 * some code doesn't need to know each function individually, and because 1100 * we would need to store typmod anyway for some of the datetime functions. 1101 * Note that currently, all variants return non-collating datatypes, so we do 1102 * not need a collation field; also, all these functions are stable. 1103 */ 1104 typedef enum SQLValueFunctionOp 1105 { 1106 SVFOP_CURRENT_DATE, 1107 SVFOP_CURRENT_TIME, 1108 SVFOP_CURRENT_TIME_N, 1109 SVFOP_CURRENT_TIMESTAMP, 1110 SVFOP_CURRENT_TIMESTAMP_N, 1111 SVFOP_LOCALTIME, 1112 SVFOP_LOCALTIME_N, 1113 SVFOP_LOCALTIMESTAMP, 1114 SVFOP_LOCALTIMESTAMP_N, 1115 SVFOP_CURRENT_ROLE, 1116 SVFOP_CURRENT_USER, 1117 SVFOP_USER, 1118 SVFOP_SESSION_USER, 1119 SVFOP_CURRENT_CATALOG, 1120 SVFOP_CURRENT_SCHEMA 1121 } SQLValueFunctionOp; 1122 1123 typedef struct SQLValueFunction 1124 { 1125 Expr xpr; 1126 SQLValueFunctionOp op; /* which function this is */ 1127 Oid type; /* result type/typmod */ 1128 int32 typmod; 1129 int location; /* token location, or -1 if unknown */ 1130 } SQLValueFunction; 1131 1132 /* 1133 * XmlExpr - various SQL/XML functions requiring special grammar productions 1134 * 1135 * 'name' carries the "NAME foo" argument (already XML-escaped). 1136 * 'named_args' and 'arg_names' represent an xml_attribute list. 1137 * 'args' carries all other arguments. 1138 * 1139 * Note: result type/typmod/collation are not stored, but can be deduced 1140 * from the XmlExprOp. The type/typmod fields are just used for display 1141 * purposes, and are NOT necessarily the true result type of the node. 1142 */ 1143 typedef enum XmlExprOp 1144 { 1145 IS_XMLCONCAT, /* XMLCONCAT(args) */ 1146 IS_XMLELEMENT, /* XMLELEMENT(name, xml_attributes, args) */ 1147 IS_XMLFOREST, /* XMLFOREST(xml_attributes) */ 1148 IS_XMLPARSE, /* XMLPARSE(text, is_doc, preserve_ws) */ 1149 IS_XMLPI, /* XMLPI(name [, args]) */ 1150 IS_XMLROOT, /* XMLROOT(xml, version, standalone) */ 1151 IS_XMLSERIALIZE, /* XMLSERIALIZE(is_document, xmlval) */ 1152 IS_DOCUMENT /* xmlval IS DOCUMENT */ 1153 } XmlExprOp; 1154 1155 typedef enum 1156 { 1157 XMLOPTION_DOCUMENT, 1158 XMLOPTION_CONTENT 1159 } XmlOptionType; 1160 1161 typedef struct XmlExpr 1162 { 1163 Expr xpr; 1164 XmlExprOp op; /* xml function ID */ 1165 char *name; /* name in xml(NAME foo ...) syntaxes */ 1166 List *named_args; /* non-XML expressions for xml_attributes */ 1167 List *arg_names; /* parallel list of Value strings */ 1168 List *args; /* list of expressions */ 1169 XmlOptionType xmloption; /* DOCUMENT or CONTENT */ 1170 Oid type; /* target type/typmod for XMLSERIALIZE */ 1171 int32 typmod; 1172 int location; /* token location, or -1 if unknown */ 1173 } XmlExpr; 1174 1175 /* ---------------- 1176 * NullTest 1177 * 1178 * NullTest represents the operation of testing a value for NULLness. 1179 * The appropriate test is performed and returned as a boolean Datum. 1180 * 1181 * When argisrow is false, this simply represents a test for the null value. 1182 * 1183 * When argisrow is true, the input expression must yield a rowtype, and 1184 * the node implements "row IS [NOT] NULL" per the SQL standard. This 1185 * includes checking individual fields for NULLness when the row datum 1186 * itself isn't NULL. 1187 * 1188 * NOTE: the combination of a rowtype input and argisrow==false does NOT 1189 * correspond to the SQL notation "row IS [NOT] NULL"; instead, this case 1190 * represents the SQL notation "row IS [NOT] DISTINCT FROM NULL". 1191 * ---------------- 1192 */ 1193 1194 typedef enum NullTestType 1195 { 1196 IS_NULL, IS_NOT_NULL 1197 } NullTestType; 1198 1199 typedef struct NullTest 1200 { 1201 Expr xpr; 1202 Expr *arg; /* input expression */ 1203 NullTestType nulltesttype; /* IS NULL, IS NOT NULL */ 1204 bool argisrow; /* T to perform field-by-field null checks */ 1205 int location; /* token location, or -1 if unknown */ 1206 } NullTest; 1207 1208 /* 1209 * BooleanTest 1210 * 1211 * BooleanTest represents the operation of determining whether a boolean 1212 * is TRUE, FALSE, or UNKNOWN (ie, NULL). All six meaningful combinations 1213 * are supported. Note that a NULL input does *not* cause a NULL result. 1214 * The appropriate test is performed and returned as a boolean Datum. 1215 */ 1216 1217 typedef enum BoolTestType 1218 { 1219 IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN 1220 } BoolTestType; 1221 1222 typedef struct BooleanTest 1223 { 1224 Expr xpr; 1225 Expr *arg; /* input expression */ 1226 BoolTestType booltesttype; /* test type */ 1227 int location; /* token location, or -1 if unknown */ 1228 } BooleanTest; 1229 1230 /* 1231 * CoerceToDomain 1232 * 1233 * CoerceToDomain represents the operation of coercing a value to a domain 1234 * type. At runtime (and not before) the precise set of constraints to be 1235 * checked will be determined. If the value passes, it is returned as the 1236 * result; if not, an error is raised. Note that this is equivalent to 1237 * RelabelType in the scenario where no constraints are applied. 1238 */ 1239 typedef struct CoerceToDomain 1240 { 1241 Expr xpr; 1242 Expr *arg; /* input expression */ 1243 Oid resulttype; /* domain type ID (result type) */ 1244 int32 resulttypmod; /* output typmod (currently always -1) */ 1245 Oid resultcollid; /* OID of collation, or InvalidOid if none */ 1246 CoercionForm coercionformat; /* how to display this node */ 1247 int location; /* token location, or -1 if unknown */ 1248 } CoerceToDomain; 1249 1250 /* 1251 * Placeholder node for the value to be processed by a domain's check 1252 * constraint. This is effectively like a Param, but can be implemented more 1253 * simply since we need only one replacement value at a time. 1254 * 1255 * Note: the typeId/typeMod/collation will be set from the domain's base type, 1256 * not the domain itself. This is because we shouldn't consider the value 1257 * to be a member of the domain if we haven't yet checked its constraints. 1258 */ 1259 typedef struct CoerceToDomainValue 1260 { 1261 Expr xpr; 1262 Oid typeId; /* type for substituted value */ 1263 int32 typeMod; /* typemod for substituted value */ 1264 Oid collation; /* collation for the substituted value */ 1265 int location; /* token location, or -1 if unknown */ 1266 } CoerceToDomainValue; 1267 1268 /* 1269 * Placeholder node for a DEFAULT marker in an INSERT or UPDATE command. 1270 * 1271 * This is not an executable expression: it must be replaced by the actual 1272 * column default expression during rewriting. But it is convenient to 1273 * treat it as an expression node during parsing and rewriting. 1274 */ 1275 typedef struct SetToDefault 1276 { 1277 Expr xpr; 1278 Oid typeId; /* type for substituted value */ 1279 int32 typeMod; /* typemod for substituted value */ 1280 Oid collation; /* collation for the substituted value */ 1281 int location; /* token location, or -1 if unknown */ 1282 } SetToDefault; 1283 1284 /* 1285 * Node representing [WHERE] CURRENT OF cursor_name 1286 * 1287 * CURRENT OF is a bit like a Var, in that it carries the rangetable index 1288 * of the target relation being constrained; this aids placing the expression 1289 * correctly during planning. We can assume however that its "levelsup" is 1290 * always zero, due to the syntactic constraints on where it can appear. 1291 * 1292 * The referenced cursor can be represented either as a hardwired string 1293 * or as a reference to a run-time parameter of type REFCURSOR. The latter 1294 * case is for the convenience of plpgsql. 1295 */ 1296 typedef struct CurrentOfExpr 1297 { 1298 Expr xpr; 1299 Index cvarno; /* RT index of target relation */ 1300 char *cursor_name; /* name of referenced cursor, or NULL */ 1301 int cursor_param; /* refcursor parameter number, or 0 */ 1302 } CurrentOfExpr; 1303 1304 /* 1305 * NextValueExpr - get next value from sequence 1306 * 1307 * This has the same effect as calling the nextval() function, but it does not 1308 * check permissions on the sequence. This is used for identity columns, 1309 * where the sequence is an implicit dependency without its own permissions. 1310 */ 1311 typedef struct NextValueExpr 1312 { 1313 Expr xpr; 1314 Oid seqid; 1315 Oid typeId; 1316 } NextValueExpr; 1317 1318 /* 1319 * InferenceElem - an element of a unique index inference specification 1320 * 1321 * This mostly matches the structure of IndexElems, but having a dedicated 1322 * primnode allows for a clean separation between the use of index parameters 1323 * by utility commands, and this node. 1324 */ 1325 typedef struct InferenceElem 1326 { 1327 Expr xpr; 1328 Node *expr; /* expression to infer from, or NULL */ 1329 Oid infercollid; /* OID of collation, or InvalidOid */ 1330 Oid inferopclass; /* OID of att opclass, or InvalidOid */ 1331 } InferenceElem; 1332 1333 /*-------------------- 1334 * TargetEntry - 1335 * a target entry (used in query target lists) 1336 * 1337 * Strictly speaking, a TargetEntry isn't an expression node (since it can't 1338 * be evaluated by ExecEvalExpr). But we treat it as one anyway, since in 1339 * very many places it's convenient to process a whole query targetlist as a 1340 * single expression tree. 1341 * 1342 * In a SELECT's targetlist, resno should always be equal to the item's 1343 * ordinal position (counting from 1). However, in an INSERT or UPDATE 1344 * targetlist, resno represents the attribute number of the destination 1345 * column for the item; so there may be missing or out-of-order resnos. 1346 * It is even legal to have duplicated resnos; consider 1347 * UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ... 1348 * The two meanings come together in the executor, because the planner 1349 * transforms INSERT/UPDATE tlists into a normalized form with exactly 1350 * one entry for each column of the destination table. Before that's 1351 * happened, however, it is risky to assume that resno == position. 1352 * Generally get_tle_by_resno() should be used rather than list_nth() 1353 * to fetch tlist entries by resno, and only in SELECT should you assume 1354 * that resno is a unique identifier. 1355 * 1356 * resname is required to represent the correct column name in non-resjunk 1357 * entries of top-level SELECT targetlists, since it will be used as the 1358 * column title sent to the frontend. In most other contexts it is only 1359 * a debugging aid, and may be wrong or even NULL. (In particular, it may 1360 * be wrong in a tlist from a stored rule, if the referenced column has been 1361 * renamed by ALTER TABLE since the rule was made. Also, the planner tends 1362 * to store NULL rather than look up a valid name for tlist entries in 1363 * non-toplevel plan nodes.) In resjunk entries, resname should be either 1364 * a specific system-generated name (such as "ctid") or NULL; anything else 1365 * risks confusing ExecGetJunkAttribute! 1366 * 1367 * ressortgroupref is used in the representation of ORDER BY, GROUP BY, and 1368 * DISTINCT items. Targetlist entries with ressortgroupref=0 are not 1369 * sort/group items. If ressortgroupref>0, then this item is an ORDER BY, 1370 * GROUP BY, and/or DISTINCT target value. No two entries in a targetlist 1371 * may have the same nonzero ressortgroupref --- but there is no particular 1372 * meaning to the nonzero values, except as tags. (For example, one must 1373 * not assume that lower ressortgroupref means a more significant sort key.) 1374 * The order of the associated SortGroupClause lists determine the semantics. 1375 * 1376 * resorigtbl/resorigcol identify the source of the column, if it is a 1377 * simple reference to a column of a base table (or view). If it is not 1378 * a simple reference, these fields are zeroes. 1379 * 1380 * If resjunk is true then the column is a working column (such as a sort key) 1381 * that should be removed from the final output of the query. Resjunk columns 1382 * must have resnos that cannot duplicate any regular column's resno. Also 1383 * note that there are places that assume resjunk columns come after non-junk 1384 * columns. 1385 *-------------------- 1386 */ 1387 typedef struct TargetEntry 1388 { 1389 Expr xpr; 1390 Expr *expr; /* expression to evaluate */ 1391 AttrNumber resno; /* attribute number (see notes above) */ 1392 char *resname; /* name of the column (could be NULL) */ 1393 Index ressortgroupref; /* nonzero if referenced by a sort/group 1394 * clause */ 1395 Oid resorigtbl; /* OID of column's source table */ 1396 AttrNumber resorigcol; /* column's number in source table */ 1397 bool resjunk; /* set to true to eliminate the attribute from 1398 * final target list */ 1399 } TargetEntry; 1400 1401 1402 /* ---------------------------------------------------------------- 1403 * node types for join trees 1404 * 1405 * The leaves of a join tree structure are RangeTblRef nodes. Above 1406 * these, JoinExpr nodes can appear to denote a specific kind of join 1407 * or qualified join. Also, FromExpr nodes can appear to denote an 1408 * ordinary cross-product join ("FROM foo, bar, baz WHERE ..."). 1409 * FromExpr is like a JoinExpr of jointype JOIN_INNER, except that it 1410 * may have any number of child nodes, not just two. 1411 * 1412 * NOTE: the top level of a Query's jointree is always a FromExpr. 1413 * Even if the jointree contains no rels, there will be a FromExpr. 1414 * 1415 * NOTE: the qualification expressions present in JoinExpr nodes are 1416 * *in addition to* the query's main WHERE clause, which appears as the 1417 * qual of the top-level FromExpr. The reason for associating quals with 1418 * specific nodes in the jointree is that the position of a qual is critical 1419 * when outer joins are present. (If we enforce a qual too soon or too late, 1420 * that may cause the outer join to produce the wrong set of NULL-extended 1421 * rows.) If all joins are inner joins then all the qual positions are 1422 * semantically interchangeable. 1423 * 1424 * NOTE: in the raw output of gram.y, a join tree contains RangeVar, 1425 * RangeSubselect, and RangeFunction nodes, which are all replaced by 1426 * RangeTblRef nodes during the parse analysis phase. Also, the top-level 1427 * FromExpr is added during parse analysis; the grammar regards FROM and 1428 * WHERE as separate. 1429 * ---------------------------------------------------------------- 1430 */ 1431 1432 /* 1433 * RangeTblRef - reference to an entry in the query's rangetable 1434 * 1435 * We could use direct pointers to the RT entries and skip having these 1436 * nodes, but multiple pointers to the same node in a querytree cause 1437 * lots of headaches, so it seems better to store an index into the RT. 1438 */ 1439 typedef struct RangeTblRef 1440 { 1441 NodeTag type; 1442 int rtindex; 1443 } RangeTblRef; 1444 1445 /*---------- 1446 * JoinExpr - for SQL JOIN expressions 1447 * 1448 * isNatural, usingClause, and quals are interdependent. The user can write 1449 * only one of NATURAL, USING(), or ON() (this is enforced by the grammar). 1450 * If he writes NATURAL then parse analysis generates the equivalent USING() 1451 * list, and from that fills in "quals" with the right equality comparisons. 1452 * If he writes USING() then "quals" is filled with equality comparisons. 1453 * If he writes ON() then only "quals" is set. Note that NATURAL/USING 1454 * are not equivalent to ON() since they also affect the output column list. 1455 * 1456 * alias is an Alias node representing the AS alias-clause attached to the 1457 * join expression, or NULL if no clause. NB: presence or absence of the 1458 * alias has a critical impact on semantics, because a join with an alias 1459 * restricts visibility of the tables/columns inside it. 1460 * 1461 * During parse analysis, an RTE is created for the Join, and its index 1462 * is filled into rtindex. This RTE is present mainly so that Vars can 1463 * be created that refer to the outputs of the join. The planner sometimes 1464 * generates JoinExprs internally; these can have rtindex = 0 if there are 1465 * no join alias variables referencing such joins. 1466 *---------- 1467 */ 1468 typedef struct JoinExpr 1469 { 1470 NodeTag type; 1471 JoinType jointype; /* type of join */ 1472 bool isNatural; /* Natural join? Will need to shape table */ 1473 Node *larg; /* left subtree */ 1474 Node *rarg; /* right subtree */ 1475 List *usingClause; /* USING clause, if any (list of String) */ 1476 Node *quals; /* qualifiers on join, if any */ 1477 Alias *alias; /* user-written alias clause, if any */ 1478 int rtindex; /* RT index assigned for join, or 0 */ 1479 } JoinExpr; 1480 1481 /*---------- 1482 * FromExpr - represents a FROM ... WHERE ... construct 1483 * 1484 * This is both more flexible than a JoinExpr (it can have any number of 1485 * children, including zero) and less so --- we don't need to deal with 1486 * aliases and so on. The output column set is implicitly just the union 1487 * of the outputs of the children. 1488 *---------- 1489 */ 1490 typedef struct FromExpr 1491 { 1492 NodeTag type; 1493 List *fromlist; /* List of join subtrees */ 1494 Node *quals; /* qualifiers on join, if any */ 1495 } FromExpr; 1496 1497 /*---------- 1498 * OnConflictExpr - represents an ON CONFLICT DO ... expression 1499 * 1500 * The optimizer requires a list of inference elements, and optionally a WHERE 1501 * clause to infer a unique index. The unique index (or, occasionally, 1502 * indexes) inferred are used to arbitrate whether or not the alternative ON 1503 * CONFLICT path is taken. 1504 *---------- 1505 */ 1506 typedef struct OnConflictExpr 1507 { 1508 NodeTag type; 1509 OnConflictAction action; /* DO NOTHING or UPDATE? */ 1510 1511 /* Arbiter */ 1512 List *arbiterElems; /* unique index arbiter list (of 1513 * InferenceElem's) */ 1514 Node *arbiterWhere; /* unique index arbiter WHERE clause */ 1515 Oid constraint; /* pg_constraint OID for arbiter */ 1516 1517 /* ON CONFLICT UPDATE */ 1518 List *onConflictSet; /* List of ON CONFLICT SET TargetEntrys */ 1519 Node *onConflictWhere; /* qualifiers to restrict UPDATE to */ 1520 int exclRelIndex; /* RT index of 'excluded' relation */ 1521 List *exclRelTlist; /* tlist of the EXCLUDED pseudo relation */ 1522 } OnConflictExpr; 1523 1524 #endif /* PRIMNODES_H */ 1525