src/libpq/include/nodes/plannodes.h

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/*-------------------------------------------------------------------------
 *
 * plannodes.h
 *        definitions for query plan nodes
 *
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/nodes/plannodes.h,v 1.80.2.1 2005/11/22 18:23:28 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef PLANNODES_H
#define PLANNODES_H

#include "access/sdir.h"
#include "nodes/bitmapset.h"
#include "nodes/primnodes.h"


/* ----------------------------------------------------------------
 *                                              node definitions
 * ----------------------------------------------------------------
 */

/* ----------------
 *              Plan node
 *
 * All plan nodes "derive" from the Plan structure by having the
 * Plan structure as the first field.  This ensures that everything works
 * when nodes are cast to Plan's.  (node pointers are frequently cast to Plan*
 * when passed around generically in the executor)
 *
 * We never actually instantiate any Plan nodes; this is just the common
 * abstract superclass for all Plan-type nodes.
 * ----------------
 */
typedef struct Plan
{
        NodeTag         type;

        /*
         * estimated execution costs for plan (see costsize.c for more info)
         */
        Cost            startup_cost;   /* cost expended before fetching any tuples */
        Cost            total_cost;             /* total cost (assuming all tuples fetched) */

        /*
         * planner's estimate of result size of this plan step
         */
        double          plan_rows;              /* number of rows plan is expected to emit */
        int                     plan_width;             /* average row width in bytes */

        /*
         * Common structural data for all Plan types.
         */
        List       *targetlist;         /* target list to be computed at this node */
        List       *qual;                       /* implicitly-ANDed qual conditions */
        struct Plan *lefttree;          /* input plan tree(s) */
        struct Plan *righttree;
        List       *initPlan;           /* Init Plan nodes (un-correlated expr
                                                                 * subselects) */

        /*
         * Information for management of parameter-change-driven rescanning
         *
         * extParam includes the paramIDs of all external PARAM_EXEC params
         * affecting this plan node or its children.  setParam params from the
         * node's initPlans are not included, but their extParams are.
         *
         * allParam includes all the extParam paramIDs, plus the IDs of local
         * params that affect the node (i.e., the setParams of its initplans).
         * These are _all_ the PARAM_EXEC params that affect this node.
         */
        Bitmapset  *extParam;
        Bitmapset  *allParam;

        /*
         * We really need in some TopPlan node to store range table and
         * resultRelation from Query there and get rid of Query itself from
         * Executor. Some other stuff like below could be put there, too.
         */
        int                     nParamExec;             /* Number of them in entire query. This is to
                                                                 * get Executor know about how many PARAM_EXEC
                                                                 * there are in query plan. */
} Plan;

/* ----------------
 *      these are are defined to avoid confusion problems with "left"
 *      and "right" and "inner" and "outer".  The convention is that
 *      the "left" plan is the "outer" plan and the "right" plan is
 *      the inner plan, but these make the code more readable.
 * ----------------
 */
#define innerPlan(node)                 (((Plan *)(node))->righttree)
#define outerPlan(node)                 (((Plan *)(node))->lefttree)


/* ----------------
 *       Result node -
 *              If no outer plan, evaluate a variable-free targetlist.
 *              If outer plan, return tuples from outer plan (after a level of
 *              projection as shown by targetlist).
 *
 * If resconstantqual isn't NULL, it represents a one-time qualification
 * test (i.e., one that doesn't depend on any variables from the outer plan,
 * so needs to be evaluated only once).
 * ----------------
 */
typedef struct Result
{
        Plan            plan;
        Node       *resconstantqual;
} Result;

/* ----------------
 *       Append node -
 *              Generate the concatenation of the results of sub-plans.
 *
 * Append nodes are sometimes used to switch between several result relations
 * (when the target of an UPDATE or DELETE is an inheritance set).      Such a
 * node will have isTarget true.  The Append executor is then responsible
 * for updating the executor state to point at the correct target relation
 * whenever it switches subplans.
 * ----------------
 */
typedef struct Append
{
        Plan            plan;
        List       *appendplans;
        bool            isTarget;
} Append;

/* ----------------
 *       BitmapAnd node -
 *              Generate the intersection of the results of sub-plans.
 *
 * The subplans must be of types that yield tuple bitmaps.      The targetlist
 * and qual fields of the plan are unused and are always NIL.
 * ----------------
 */
typedef struct BitmapAnd
{
        Plan            plan;
        List       *bitmapplans;
} BitmapAnd;

/* ----------------
 *       BitmapOr node -
 *              Generate the union of the results of sub-plans.
 *
 * The subplans must be of types that yield tuple bitmaps.      The targetlist
 * and qual fields of the plan are unused and are always NIL.
 * ----------------
 */
typedef struct BitmapOr
{
        Plan            plan;
        List       *bitmapplans;
} BitmapOr;

/*
 * ==========
 * Scan nodes
 * ==========
 */
typedef struct Scan
{
        Plan            plan;
        Index           scanrelid;              /* relid is index into the range table */
} Scan;

/* ----------------
 *              sequential scan node
 * ----------------
 */
typedef Scan SeqScan;

/* ----------------
 *              index scan node
 *
 * indexqualorig is an implicitly-ANDed list of index qual expressions, each
 * in the same form it appeared in the query WHERE condition.  Each should
 * be of the form (indexkey OP comparisonval) or (comparisonval OP indexkey).
 * The indexkey is a Var or expression referencing column(s) of the index's
 * base table.  The comparisonval might be any expression, but it won't use
 * any columns of the base table.
 *
 * indexqual has the same form, but the expressions have been commuted if
 * necessary to put the indexkeys on the left, and the indexkeys are replaced
 * by Var nodes identifying the index columns (varattno is the index column
 * position, not the base table's column, even though varno is for the base
 * table).      This is a bit hokey ... would be cleaner to use a special-purpose
 * node type that could not be mistaken for a regular Var.      But it will do
 * for now.
 *
 * indexstrategy and indexsubtype are lists corresponding one-to-one with
 * indexqual; they give information about the indexable operators that appear
 * at the top of each indexqual.
 * ----------------
 */
typedef struct IndexScan
{
        Scan            scan;
        Oid                     indexid;                /* OID of index to scan */
        List       *indexqual;          /* list of index quals (OpExprs) */
        List       *indexqualorig;      /* the same in original form */
        List       *indexstrategy;      /* integer list of strategy numbers */
        List       *indexsubtype;       /* OID list of strategy subtypes */
        ScanDirection indexorderdir;    /* forward or backward or don't care */
} IndexScan;

/* ----------------
 *              bitmap index scan node
 *
 * BitmapIndexScan delivers a bitmap of potential tuple locations;
 * it does not access the heap itself.  The bitmap is used by an
 * ancestor BitmapHeapScan node, possibly after passing through
 * intermediate BitmapAnd and/or BitmapOr nodes to combine it with
 * the results of other BitmapIndexScans.
 *
 * The fields have the same meanings as for IndexScan, except we don't
 * store a direction flag because direction is uninteresting.
 *
 * In a BitmapIndexScan plan node, the targetlist and qual fields are
 * not used and are always NIL.  The indexqualorig field is unused at
 * run time too, but is saved for the benefit of EXPLAIN.
 * ----------------
 */
typedef struct BitmapIndexScan
{
        Scan            scan;
        Oid                     indexid;                /* OID of index to scan */
        List       *indexqual;          /* list of index quals (OpExprs) */
        List       *indexqualorig;      /* the same in original form */
        List       *indexstrategy;      /* integer list of strategy numbers */
        List       *indexsubtype;       /* OID list of strategy subtypes */
} BitmapIndexScan;

/* ----------------
 *              bitmap sequential scan node
 *
 * This needs a copy of the qual conditions being used by the input index
 * scans because there are various cases where we need to recheck the quals;
 * for example, when the bitmap is lossy about the specific rows on a page
 * that meet the index condition.
 * ----------------
 */
typedef struct BitmapHeapScan
{
        Scan            scan;
        List       *bitmapqualorig; /* index quals, in standard expr form */
} BitmapHeapScan;

/* ----------------
 *              tid scan node
 * ----------------
 */
typedef struct TidScan
{
        Scan            scan;
        List       *tideval;
} TidScan;

/* ----------------
 *              subquery scan node
 *
 * SubqueryScan is for scanning the output of a sub-query in the range table.
 * We need a special plan node above the sub-query's plan as a place to switch
 * execution contexts.  Although we are not scanning a physical relation,
 * we make this a descendant of Scan anyway for code-sharing purposes.
 *
 * Note: we store the sub-plan in the type-specific subplan field, not in
 * the generic lefttree field as you might expect.      This is because we do
 * not want plan-tree-traversal routines to recurse into the subplan without
 * knowing that they are changing Query contexts.
 * ----------------
 */
typedef struct SubqueryScan
{
        Scan            scan;
        Plan       *subplan;
} SubqueryScan;

/* ----------------
 *              FunctionScan node
 * ----------------
 */
typedef struct FunctionScan
{
        Scan            scan;
        /* no other fields needed at present */
} FunctionScan;

/*
 * ==========
 * Join nodes
 * ==========
 */

/* ----------------
 *              Join node
 *
 * jointype:    rule for joining tuples from left and right subtrees
 * joinqual:    qual conditions that came from JOIN/ON or JOIN/USING
 *                              (plan.qual contains conditions that came from WHERE)
 *
 * When jointype is INNER, joinqual and plan.qual are semantically
 * interchangeable.  For OUTER jointypes, the two are *not* interchangeable;
 * only joinqual is used to determine whether a match has been found for
 * the purpose of deciding whether to generate null-extended tuples.
 * (But plan.qual is still applied before actually returning a tuple.)
 * For an outer join, only joinquals are allowed to be used as the merge
 * or hash condition of a merge or hash join.
 * ----------------
 */
typedef struct Join
{
        Plan            plan;
        JoinType        jointype;
        List       *joinqual;           /* JOIN quals (in addition to plan.qual) */
} Join;

/* ----------------
 *              nest loop join node
 * ----------------
 */
typedef struct NestLoop
{
        Join            join;
} NestLoop;

/* ----------------
 *              merge join node
 * ----------------
 */
typedef struct MergeJoin
{
        Join            join;
        List       *mergeclauses;
} MergeJoin;

/* ----------------
 *              hash join (probe) node
 * ----------------
 */
typedef struct HashJoin
{
        Join            join;
        List       *hashclauses;
} HashJoin;

/* ----------------
 *              materialization node
 * ----------------
 */
typedef struct Material
{
        Plan            plan;
} Material;

/* ----------------
 *              sort node
 * ----------------
 */
typedef struct Sort
{
        Plan            plan;
        int                     numCols;                /* number of sort-key columns */
        AttrNumber *sortColIdx;         /* their indexes in the target list */
        Oid                *sortOperators;      /* OIDs of operators to sort them by */
} Sort;

/* ---------------
 *       group node -
 *              Used for queries with GROUP BY (but no aggregates) specified.
 *              The input must be presorted according to the grouping columns.
 * ---------------
 */
typedef struct Group
{
        Plan            plan;
        int                     numCols;                /* number of grouping columns */
        AttrNumber *grpColIdx;          /* their indexes in the target list */
} Group;

/* ---------------
 *              aggregate node
 *
 * An Agg node implements plain or grouped aggregation.  For grouped
 * aggregation, we can work with presorted input or unsorted input;
 * the latter strategy uses an internal hashtable.
 *
 * Notice the lack of any direct info about the aggregate functions to be
 * computed.  They are found by scanning the node's tlist and quals during
 * executor startup.  (It is possible that there are no aggregate functions;
 * this could happen if they get optimized away by constant-folding, or if
 * we are using the Agg node to implement hash-based grouping.)
 * ---------------
 */
typedef enum AggStrategy
{
        AGG_PLAIN,                                      /* simple agg across all input rows */
        AGG_SORTED,                                     /* grouped agg, input must be sorted */
        AGG_HASHED                                      /* grouped agg, use internal hashtable */
} AggStrategy;

typedef struct Agg
{
        Plan            plan;
        AggStrategy aggstrategy;
        int                     numCols;                /* number of grouping columns */
        AttrNumber *grpColIdx;          /* their indexes in the target list */
        long            numGroups;              /* estimated number of groups in input */
} Agg;

/* ----------------
 *              unique node
 * ----------------
 */
typedef struct Unique
{
        Plan            plan;
        int                     numCols;                /* number of columns to check for uniqueness */
        AttrNumber *uniqColIdx;         /* indexes into the target list */
} Unique;

/* ----------------
 *              hash build node
 * ----------------
 */
typedef struct Hash
{
        Plan            plan;
        /* all other info is in the parent HashJoin node */
} Hash;

/* ----------------
 *              setop node
 * ----------------
 */
typedef enum SetOpCmd
{
        SETOPCMD_INTERSECT,
        SETOPCMD_INTERSECT_ALL,
        SETOPCMD_EXCEPT,
        SETOPCMD_EXCEPT_ALL
} SetOpCmd;

typedef struct SetOp
{
        Plan            plan;
        SetOpCmd        cmd;                    /* what to do */
        int                     numCols;                /* number of columns to check for
                                                                 * duplicate-ness */
        AttrNumber *dupColIdx;          /* indexes into the target list */
        AttrNumber      flagColIdx;
} SetOp;

/* ----------------
 *              limit node
 * ----------------
 */
typedef struct Limit
{
        Plan            plan;
        Node       *limitOffset;        /* OFFSET parameter, or NULL if none */
        Node       *limitCount;         /* COUNT parameter, or NULL if none */
} Limit;

#endif   /* PLANNODES_H */