src/include/nodes/plannodes.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * plannodes.h
   4  *        definitions for query plan nodes
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * $PostgreSQL$
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef PLANNODES_H
  15 #define PLANNODES_H
  16
  17 #include "access/sdir.h"
  18 #include "nodes/bitmapset.h"
  19 #include "nodes/primnodes.h"
  20 #include "storage/itemptr.h"
  21
  22
  23 /* ----------------------------------------------------------------
  24  *                                              node definitions
  25  * ----------------------------------------------------------------
  26  */
  27
  28 /* ----------------
  29  *              PlannedStmt node
  30  *
  31  * The output of the planner is a Plan tree headed by a PlannedStmt node.
  32  * PlannedStmt holds the "one time" information needed by the executor.
  33  * ----------------
  34  */
  35 typedef struct PlannedStmt
  36 {
  37         NodeTag         type;
  38
  39         CmdType         commandType;    /* select|insert|update|delete */
  40
  41         bool            canSetTag;              /* do I set the command result tag? */
  42
  43         bool            transientPlan;  /* redo plan when TransactionXmin changes? */
  44
  45         struct Plan *planTree;          /* tree of Plan nodes */
  46
  47         List       *rtable;                     /* list of RangeTblEntry nodes */
  48
  49         /* rtable indexes of target relations for INSERT/UPDATE/DELETE */
  50         List       *resultRelations;    /* integer list of RT indexes, or NIL */
  51
  52         Node       *utilityStmt;        /* non-null if this is DECLARE CURSOR */
  53
  54         IntoClause *intoClause;         /* target for SELECT INTO / CREATE TABLE AS */
  55
  56         List       *subplans;           /* Plan trees for SubPlan expressions */
  57
  58         Bitmapset  *rewindPlanIDs;      /* indices of subplans that require REWIND */
  59
  60         /*
  61          * If the query has a returningList then the planner will store a list of
  62          * processed targetlists (one per result relation) here.  We must have a
  63          * separate RETURNING targetlist for each result rel because column
  64          * numbers may vary within an inheritance tree.  In the targetlists, Vars
  65          * referencing the result relation will have their original varno and
  66          * varattno, while Vars referencing other rels will be converted to have
  67          * varno OUTER and varattno referencing a resjunk entry in the top plan
  68          * node's targetlist.
  69          */
  70         List       *returningLists; /* list of lists of TargetEntry, or NIL */
  71
  72         List       *rowMarks;           /* a list of RowMarkClause's */
  73
  74         List       *relationOids;       /* OIDs of relations the plan depends on */
  75
  76         List       *invalItems;         /* other dependencies, as PlanInvalItems */
  77
  78         int                     nParamExec;             /* number of PARAM_EXEC Params used */
  79 } PlannedStmt;
  80
  81 /* macro for fetching the Plan associated with a SubPlan node */
  82 #define exec_subplan_get_plan(plannedstmt, subplan) \
  83         ((Plan *) list_nth((plannedstmt)->subplans, (subplan)->plan_id - 1))
  84
  85
  86 /* ----------------
  87  *              Plan node
  88  *
  89  * All plan nodes "derive" from the Plan structure by having the
  90  * Plan structure as the first field.  This ensures that everything works
  91  * when nodes are cast to Plan's.  (node pointers are frequently cast to Plan*
  92  * when passed around generically in the executor)
  93  *
  94  * We never actually instantiate any Plan nodes; this is just the common
  95  * abstract superclass for all Plan-type nodes.
  96  * ----------------
  97  */
  98 typedef struct Plan
  99 {
 100         NodeTag         type;
 101
 102         /*
 103          * estimated execution costs for plan (see costsize.c for more info)
 104          */
 105         Cost            startup_cost;   /* cost expended before fetching any tuples */
 106         Cost            total_cost;             /* total cost (assuming all tuples fetched) */
 107
 108         /*
 109          * planner's estimate of result size of this plan step
 110          */
 111         double          plan_rows;              /* number of rows plan is expected to emit */
 112         int                     plan_width;             /* average row width in bytes */
 113
 114         /*
 115          * Common structural data for all Plan types.
 116          */
 117         List       *targetlist;         /* target list to be computed at this node */
 118         List       *qual;                       /* implicitly-ANDed qual conditions */
 119         struct Plan *lefttree;          /* input plan tree(s) */
 120         struct Plan *righttree;
 121         List       *initPlan;           /* Init Plan nodes (un-correlated expr
 122                                                                  * subselects) */
 123
 124         /*
 125          * Information for management of parameter-change-driven rescanning
 126          *
 127          * extParam includes the paramIDs of all external PARAM_EXEC params
 128          * affecting this plan node or its children.  setParam params from the
 129          * node's initPlans are not included, but their extParams are.
 130          *
 131          * allParam includes all the extParam paramIDs, plus the IDs of local
 132          * params that affect the node (i.e., the setParams of its initplans).
 133          * These are _all_ the PARAM_EXEC params that affect this node.
 134          */
 135         Bitmapset  *extParam;
 136         Bitmapset  *allParam;
 137 } Plan;
 138
 139 /* ----------------
 140  *      these are are defined to avoid confusion problems with "left"
 141  *      and "right" and "inner" and "outer".  The convention is that
 142  *      the "left" plan is the "outer" plan and the "right" plan is
 143  *      the inner plan, but these make the code more readable.
 144  * ----------------
 145  */
 146 #define innerPlan(node)                 (((Plan *)(node))->righttree)
 147 #define outerPlan(node)                 (((Plan *)(node))->lefttree)
 148
 149
 150 /* ----------------
 151  *       Result node -
 152  *              If no outer plan, evaluate a variable-free targetlist.
 153  *              If outer plan, return tuples from outer plan (after a level of
 154  *              projection as shown by targetlist).
 155  *
 156  * If resconstantqual isn't NULL, it represents a one-time qualification
 157  * test (i.e., one that doesn't depend on any variables from the outer plan,
 158  * so needs to be evaluated only once).
 159  * ----------------
 160  */
 161 typedef struct Result
 162 {
 163         Plan            plan;
 164         Node       *resconstantqual;
 165 } Result;
 166
 167 /* ----------------
 168  *       Append node -
 169  *              Generate the concatenation of the results of sub-plans.
 170  *
 171  * Append nodes are sometimes used to switch between several result relations
 172  * (when the target of an UPDATE or DELETE is an inheritance set).      Such a
 173  * node will have isTarget true.  The Append executor is then responsible
 174  * for updating the executor state to point at the correct target relation
 175  * whenever it switches subplans.
 176  * ----------------
 177  */
 178 typedef struct Append
 179 {
 180         Plan            plan;
 181         List       *appendplans;
 182         bool            isTarget;
 183 } Append;
 184
 185 /* ----------------
 186  *       BitmapAnd node -
 187  *              Generate the intersection of the results of sub-plans.
 188  *
 189  * The subplans must be of types that yield tuple bitmaps.      The targetlist
 190  * and qual fields of the plan are unused and are always NIL.
 191  * ----------------
 192  */
 193 typedef struct BitmapAnd
 194 {
 195         Plan            plan;
 196         List       *bitmapplans;
 197 } BitmapAnd;
 198
 199 /* ----------------
 200  *       BitmapOr node -
 201  *              Generate the union of the results of sub-plans.
 202  *
 203  * The subplans must be of types that yield tuple bitmaps.      The targetlist
 204  * and qual fields of the plan are unused and are always NIL.
 205  * ----------------
 206  */
 207 typedef struct BitmapOr
 208 {
 209         Plan            plan;
 210         List       *bitmapplans;
 211 } BitmapOr;
 212
 213 /*
 214  * ==========
 215  * Scan nodes
 216  * ==========
 217  */
 218 typedef struct Scan
 219 {
 220         Plan            plan;
 221         Index           scanrelid;              /* relid is index into the range table */
 222 } Scan;
 223
 224 /* ----------------
 225  *              sequential scan node
 226  * ----------------
 227  */
 228 typedef Scan SeqScan;
 229
 230 /* ----------------
 231  *              index scan node
 232  *
 233  * indexqualorig is an implicitly-ANDed list of index qual expressions, each
 234  * in the same form it appeared in the query WHERE condition.  Each should
 235  * be of the form (indexkey OP comparisonval) or (comparisonval OP indexkey).
 236  * The indexkey is a Var or expression referencing column(s) of the index's
 237  * base table.  The comparisonval might be any expression, but it won't use
 238  * any columns of the base table.
 239  *
 240  * indexqual has the same form, but the expressions have been commuted if
 241  * necessary to put the indexkeys on the left, and the indexkeys are replaced
 242  * by Var nodes identifying the index columns (varattno is the index column
 243  * position, not the base table's column, even though varno is for the base
 244  * table).      This is a bit hokey ... would be cleaner to use a special-purpose
 245  * node type that could not be mistaken for a regular Var.      But it will do
 246  * for now.
 247  * ----------------
 248  */
 249 typedef struct IndexScan
 250 {
 251         Scan            scan;
 252         Oid                     indexid;                /* OID of index to scan */
 253         List       *indexqual;          /* list of index quals (OpExprs) */
 254         List       *indexqualorig;      /* the same in original form */
 255         ScanDirection indexorderdir;    /* forward or backward or don't care */
 256 } IndexScan;
 257
 258 /* ----------------
 259  *              bitmap index scan node
 260  *
 261  * BitmapIndexScan delivers a bitmap of potential tuple locations;
 262  * it does not access the heap itself.  The bitmap is used by an
 263  * ancestor BitmapHeapScan node, possibly after passing through
 264  * intermediate BitmapAnd and/or BitmapOr nodes to combine it with
 265  * the results of other BitmapIndexScans.
 266  *
 267  * The fields have the same meanings as for IndexScan, except we don't
 268  * store a direction flag because direction is uninteresting.
 269  *
 270  * In a BitmapIndexScan plan node, the targetlist and qual fields are
 271  * not used and are always NIL.  The indexqualorig field is unused at
 272  * run time too, but is saved for the benefit of EXPLAIN.
 273  * ----------------
 274  */
 275 typedef struct BitmapIndexScan
 276 {
 277         Scan            scan;
 278         Oid                     indexid;                /* OID of index to scan */
 279         List       *indexqual;          /* list of index quals (OpExprs) */
 280         List       *indexqualorig;      /* the same in original form */
 281 } BitmapIndexScan;
 282
 283 /* ----------------
 284  *              bitmap sequential scan node
 285  *
 286  * This needs a copy of the qual conditions being used by the input index
 287  * scans because there are various cases where we need to recheck the quals;
 288  * for example, when the bitmap is lossy about the specific rows on a page
 289  * that meet the index condition.
 290  * ----------------
 291  */
 292 typedef struct BitmapHeapScan
 293 {
 294         Scan            scan;
 295         List       *bitmapqualorig; /* index quals, in standard expr form */
 296 } BitmapHeapScan;
 297
 298 /* ----------------
 299  *              tid scan node
 300  *
 301  * tidquals is an implicitly OR'ed list of qual expressions of the form
 302  * "CTID = pseudoconstant" or "CTID = ANY(pseudoconstant_array)".
 303  * ----------------
 304  */
 305 typedef struct TidScan
 306 {
 307         Scan            scan;
 308         List       *tidquals;           /* qual(s) involving CTID = something */
 309 } TidScan;
 310
 311 /* ----------------
 312  *              subquery scan node
 313  *
 314  * SubqueryScan is for scanning the output of a sub-query in the range table.
 315  * We often need an extra plan node above the sub-query's plan to perform
 316  * expression evaluations (which we can't push into the sub-query without
 317  * risking changing its semantics).  Although we are not scanning a physical
 318  * relation, we make this a descendant of Scan anyway for code-sharing
 319  * purposes.
 320  *
 321  * Note: we store the sub-plan in the type-specific subplan field, not in
 322  * the generic lefttree field as you might expect.      This is because we do
 323  * not want plan-tree-traversal routines to recurse into the subplan without
 324  * knowing that they are changing Query contexts.
 325  *
 326  * Note: subrtable is used just to carry the subquery rangetable from
 327  * createplan.c to setrefs.c; it should always be NIL by the time the
 328  * executor sees the plan.
 329  * ----------------
 330  */
 331 typedef struct SubqueryScan
 332 {
 333         Scan            scan;
 334         Plan       *subplan;
 335         List       *subrtable;          /* temporary workspace for planner */
 336 } SubqueryScan;
 337
 338 /* ----------------
 339  *              FunctionScan node
 340  * ----------------
 341  */
 342 typedef struct FunctionScan
 343 {
 344         Scan            scan;
 345         Node       *funcexpr;           /* expression tree for func call */
 346         List       *funccolnames;       /* output column names (string Value nodes) */
 347         List       *funccoltypes;       /* OID list of column type OIDs */
 348         List       *funccoltypmods; /* integer list of column typmods */
 349 } FunctionScan;
 350
 351 /* ----------------
 352  *              ValuesScan node
 353  * ----------------
 354  */
 355 typedef struct ValuesScan
 356 {
 357         Scan            scan;
 358         List       *values_lists;       /* list of expression lists */
 359 } ValuesScan;
 360
 361 /*
 362  * ==========
 363  * Join nodes
 364  * ==========
 365  */
 366
 367 /* ----------------
 368  *              Join node
 369  *
 370  * jointype:    rule for joining tuples from left and right subtrees
 371  * joinqual:    qual conditions that came from JOIN/ON or JOIN/USING
 372  *                              (plan.qual contains conditions that came from WHERE)
 373  *
 374  * When jointype is INNER, joinqual and plan.qual are semantically
 375  * interchangeable.  For OUTER jointypes, the two are *not* interchangeable;
 376  * only joinqual is used to determine whether a match has been found for
 377  * the purpose of deciding whether to generate null-extended tuples.
 378  * (But plan.qual is still applied before actually returning a tuple.)
 379  * For an outer join, only joinquals are allowed to be used as the merge
 380  * or hash condition of a merge or hash join.
 381  * ----------------
 382  */
 383 typedef struct Join
 384 {
 385         Plan            plan;
 386         JoinType        jointype;
 387         List       *joinqual;           /* JOIN quals (in addition to plan.qual) */
 388 } Join;
 389
 390 /* ----------------
 391  *              nest loop join node
 392  * ----------------
 393  */
 394 typedef struct NestLoop
 395 {
 396         Join            join;
 397 } NestLoop;
 398
 399 /* ----------------
 400  *              merge join node
 401  *
 402  * The expected ordering of each mergeable column is described by a btree
 403  * opfamily OID, a direction (BTLessStrategyNumber or BTGreaterStrategyNumber)
 404  * and a nulls-first flag.      Note that the two sides of each mergeclause may
 405  * be of different datatypes, but they are ordered the same way according to
 406  * the common opfamily.  The operator in each mergeclause must be an equality
 407  * operator of the indicated opfamily.
 408  * ----------------
 409  */
 410 typedef struct MergeJoin
 411 {
 412         Join            join;
 413         List       *mergeclauses;       /* mergeclauses as expression trees */
 414         /* these are arrays, but have the same length as the mergeclauses list: */
 415         Oid                *mergeFamilies;      /* per-clause OIDs of btree opfamilies */
 416         int                *mergeStrategies;    /* per-clause ordering (ASC or DESC) */
 417         bool       *mergeNullsFirst;    /* per-clause nulls ordering */
 418 } MergeJoin;
 419
 420 /* ----------------
 421  *              hash join (probe) node
 422  * ----------------
 423  */
 424 typedef struct HashJoin
 425 {
 426         Join            join;
 427         List       *hashclauses;
 428 } HashJoin;
 429
 430 /* ----------------
 431  *              materialization node
 432  * ----------------
 433  */
 434 typedef struct Material
 435 {
 436         Plan            plan;
 437 } Material;
 438
 439 /* ----------------
 440  *              sort node
 441  * ----------------
 442  */
 443 typedef struct Sort
 444 {
 445         Plan            plan;
 446         int                     numCols;                /* number of sort-key columns */
 447         AttrNumber *sortColIdx;         /* their indexes in the target list */
 448         Oid                *sortOperators;      /* OIDs of operators to sort them by */
 449         bool       *nullsFirst;         /* NULLS FIRST/LAST directions */
 450 } Sort;
 451
 452 /* ---------------
 453  *       group node -
 454  *              Used for queries with GROUP BY (but no aggregates) specified.
 455  *              The input must be presorted according to the grouping columns.
 456  * ---------------
 457  */
 458 typedef struct Group
 459 {
 460         Plan            plan;
 461         int                     numCols;                /* number of grouping columns */
 462         AttrNumber *grpColIdx;          /* their indexes in the target list */
 463         Oid                *grpOperators;       /* equality operators to compare with */
 464 } Group;
 465
 466 /* ---------------
 467  *              aggregate node
 468  *
 469  * An Agg node implements plain or grouped aggregation.  For grouped
 470  * aggregation, we can work with presorted input or unsorted input;
 471  * the latter strategy uses an internal hashtable.
 472  *
 473  * Notice the lack of any direct info about the aggregate functions to be
 474  * computed.  They are found by scanning the node's tlist and quals during
 475  * executor startup.  (It is possible that there are no aggregate functions;
 476  * this could happen if they get optimized away by constant-folding, or if
 477  * we are using the Agg node to implement hash-based grouping.)
 478  * ---------------
 479  */
 480 typedef enum AggStrategy
 481 {
 482         AGG_PLAIN,                                      /* simple agg across all input rows */
 483         AGG_SORTED,                                     /* grouped agg, input must be sorted */
 484         AGG_HASHED                                      /* grouped agg, use internal hashtable */
 485 } AggStrategy;
 486
 487 typedef struct Agg
 488 {
 489         Plan            plan;
 490         AggStrategy aggstrategy;
 491         int                     numCols;                /* number of grouping columns */
 492         AttrNumber *grpColIdx;          /* their indexes in the target list */
 493         Oid                *grpOperators;       /* equality operators to compare with */
 494         long            numGroups;              /* estimated number of groups in input */
 495 } Agg;
 496
 497 /* ----------------
 498  *              unique node
 499  * ----------------
 500  */
 501 typedef struct Unique
 502 {
 503         Plan            plan;
 504         int                     numCols;                /* number of columns to check for uniqueness */
 505         AttrNumber *uniqColIdx;         /* their indexes in the target list */
 506         Oid                *uniqOperators;      /* equality operators to compare with */
 507 } Unique;
 508
 509 /* ----------------
 510  *              hash build node
 511  * ----------------
 512  */
 513 typedef struct Hash
 514 {
 515         Plan            plan;
 516         /* all other info is in the parent HashJoin node */
 517 } Hash;
 518
 519 /* ----------------
 520  *              setop node
 521  * ----------------
 522  */
 523 typedef enum SetOpCmd
 524 {
 525         SETOPCMD_INTERSECT,
 526         SETOPCMD_INTERSECT_ALL,
 527         SETOPCMD_EXCEPT,
 528         SETOPCMD_EXCEPT_ALL
 529 } SetOpCmd;
 530
 531 typedef enum SetOpStrategy
 532 {
 533         SETOP_SORTED,                           /* input must be sorted */
 534         SETOP_HASHED                            /* use internal hashtable */
 535 } SetOpStrategy;
 536
 537 typedef struct SetOp
 538 {
 539         Plan            plan;
 540         SetOpCmd        cmd;                    /* what to do */
 541         SetOpStrategy strategy;         /* how to do it */
 542         int                     numCols;                /* number of columns to check for
 543                                                                  * duplicate-ness */
 544         AttrNumber *dupColIdx;          /* their indexes in the target list */
 545         Oid                *dupOperators;       /* equality operators to compare with */
 546         AttrNumber      flagColIdx;             /* where is the flag column, if any */
 547         int                     firstFlag;              /* flag value for first input relation */
 548         long            numGroups;              /* estimated number of groups in input */
 549 } SetOp;
 550
 551 /* ----------------
 552  *              limit node
 553  *
 554  * Note: as of Postgres 8.2, the offset and count expressions are expected
 555  * to yield int8, rather than int4 as before.
 556  * ----------------
 557  */
 558 typedef struct Limit
 559 {
 560         Plan            plan;
 561         Node       *limitOffset;        /* OFFSET parameter, or NULL if none */
 562         Node       *limitCount;         /* COUNT parameter, or NULL if none */
 563 } Limit;
 564
 565
 566 /*
 567  * Plan invalidation info
 568  *
 569  * We track the objects on which a PlannedStmt depends in two ways:
 570  * relations are recorded as a simple list of OIDs, and everything else
 571  * is represented as a list of PlanInvalItems.  A PlanInvalItem is designed
 572  * to be used with the syscache invalidation mechanism, so it identifies a
 573  * system catalog entry by cache ID and tuple TID.
 574  */
 575 typedef struct PlanInvalItem
 576 {
 577         NodeTag         type;
 578         int                     cacheId;                /* a syscache ID, see utils/syscache.h */
 579         ItemPointerData tupleId;        /* TID of the object's catalog tuple */
 580 } PlanInvalItem;
 581
 582 #endif   /* PLANNODES_H */