1996-08-28 03:59:28 +02:00
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/*-------------------------------------------------------------------------
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*
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1999-02-14 00:22:53 +01:00
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* relation.h
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1997-09-07 07:04:48 +02:00
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* Definitions for internal planner nodes.
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1996-08-28 03:59:28 +02:00
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*
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*
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2000-01-26 06:58:53 +01:00
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions Copyright (c) 1994, Regents of the University of California
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1996-08-28 03:59:28 +02:00
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*
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2000-11-12 01:37:02 +01:00
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* $Id: relation.h,v 1.50 2000/11/12 00:37:01 tgl Exp $
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1996-08-28 03:59:28 +02:00
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef RELATION_H
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#define RELATION_H
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2000-02-15 21:49:31 +01:00
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#include "access/sdir.h"
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1999-07-16 01:04:24 +02:00
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#include "nodes/parsenodes.h"
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1996-08-28 03:59:28 +02:00
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/*
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1999-02-18 01:49:48 +01:00
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* Relids
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1997-09-07 07:04:48 +02:00
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* List of relation identifiers (indexes into the rangetable).
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1999-08-16 04:17:58 +02:00
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*
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* Note: these are lists of integers, not Nodes.
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1996-08-28 03:59:28 +02:00
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*/
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1999-02-18 01:49:48 +01:00
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typedef List *Relids;
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1996-08-28 03:59:28 +02:00
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2000-02-15 21:49:31 +01:00
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/*
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* When looking for a "cheapest path", this enum specifies whether we want
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* cheapest startup cost or cheapest total cost.
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*/
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2000-04-12 19:17:23 +02:00
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typedef enum CostSelector
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{
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STARTUP_COST, TOTAL_COST
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} CostSelector;
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2000-02-15 21:49:31 +01:00
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2000-09-29 20:21:41 +02:00
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/*----------
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1998-07-18 06:22:52 +02:00
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* RelOptInfo
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1999-08-16 04:17:58 +02:00
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* Per-relation information for planning/optimization
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1996-08-28 03:59:28 +02:00
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*
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2000-09-29 20:21:41 +02:00
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* For planning purposes, a "base rel" is either a plain relation (a
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* table) or the output of a sub-SELECT that appears in the range table.
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* In either case it is uniquely identified by an RT index. A "joinrel"
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* is the joining of two or more base rels. A joinrel is identified by
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* the set of RT indexes for its component baserels.
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*
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* Note that there is only one joinrel for any given set of component
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* baserels, no matter what order we assemble them in; so an unordered
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* set is the right datatype to identify it with.
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*
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1997-09-07 07:04:48 +02:00
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* Parts of this data structure are specific to various scan and join
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* mechanisms. It didn't seem worth creating new node types for them.
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1996-08-28 03:59:28 +02:00
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*
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1999-08-16 04:17:58 +02:00
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* relids - List of base-relation identifiers; it is a base relation
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* if there is just one, a join relation if more than one
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2000-01-09 01:26:47 +01:00
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* rows - estimated number of tuples in the relation after restriction
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* clauses have been applied (ie, output rows of a plan for it)
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1999-08-16 04:17:58 +02:00
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* width - avg. number of bytes per tuple in the relation after the
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2000-01-09 01:26:47 +01:00
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* appropriate projections have been done (ie, output width)
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2000-02-15 21:49:31 +01:00
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* targetlist - List of TargetEntry nodes for the attributes we need
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* to output from this relation
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1999-08-16 04:17:58 +02:00
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* pathlist - List of Path nodes, one for each potentially useful
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* method of generating the relation
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2000-02-15 21:49:31 +01:00
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* cheapest_startup_path - the pathlist member with lowest startup cost
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* (regardless of its ordering)
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* cheapest_total_path - the pathlist member with lowest total cost
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* (regardless of its ordering)
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1999-08-16 04:17:58 +02:00
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* pruneable - flag to let the planner know whether it can prune the
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* pathlist of this RelOptInfo or not.
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1996-08-28 03:59:28 +02:00
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*
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2000-01-09 01:26:47 +01:00
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* * If the relation is a base relation it will have these fields set:
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1999-08-16 04:17:58 +02:00
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*
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2000-09-29 20:21:41 +02:00
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* issubquery - true if baserel is a subquery RTE rather than a table
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* indexed - true if the relation has secondary indices (always false
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* if it's a subquery)
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* pages - number of disk pages in relation (zero if a subquery)
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2000-01-09 01:26:47 +01:00
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* tuples - number of tuples in relation (not considering restrictions)
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2000-09-29 20:21:41 +02:00
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* subplan - plan for subquery (NULL if it's a plain table)
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*
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* Note: for a subquery, tuples and subplan are not set immediately
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* upon creation of the RelOptInfo object; they are filled in when
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* set_base_rel_pathlist processes the object.
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1999-08-16 04:17:58 +02:00
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*
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2000-11-12 01:37:02 +01:00
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* Note: if a base relation is the root of an inheritance tree
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* (SELECT FROM foo*) it is still considered a base rel. We will
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* generate a list of candidate Paths for accessing that table itself,
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* and also generate baserel RelOptInfo nodes for each child table,
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* with their own candidate Path lists. Then, an AppendPath is built
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* from the cheapest Path for each of these tables, and set to be the
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* only available Path for the inheritance baserel.
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*
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1997-09-07 07:04:48 +02:00
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* * The presence of the remaining fields depends on the restrictions
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1999-08-16 04:17:58 +02:00
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* and joins that the relation participates in:
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1996-08-28 03:59:28 +02:00
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*
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2000-02-07 05:41:04 +01:00
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* baserestrictinfo - List of RestrictInfo nodes, containing info about
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* each qualification clause in which this relation
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* participates (only used for base rels)
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2000-02-15 21:49:31 +01:00
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* baserestrictcost - Estimated cost of evaluating the baserestrictinfo
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* clauses at a single tuple (only used for base rels)
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2000-09-12 23:07:18 +02:00
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* outerjoinset - If the rel appears within the nullable side of an outer
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* join, the list of all relids participating in the highest
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* such outer join; else NIL (only used for base rels)
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1997-09-07 07:04:48 +02:00
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* joininfo - List of JoinInfo nodes, containing info about each join
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* clause in which this relation participates
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* innerjoin - List of Path nodes that represent indices that may be used
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1999-08-16 04:17:58 +02:00
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* as inner paths of nestloop joins. This field is non-null
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* only for base rels, since join rels have no indices.
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2000-02-07 05:41:04 +01:00
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*
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* Note: Keeping a restrictinfo list in the RelOptInfo is useful only for
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* base rels, because for a join rel the set of clauses that are treated as
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* restrict clauses varies depending on which sub-relations we choose to join.
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* (For example, in a 3-base-rel join, a clause relating rels 1 and 2 must be
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* treated as a restrictclause if we join {1} and {2 3} to make {1 2 3}; but
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* if we join {1 2} and {3} then that clause will be a restrictclause in {1 2}
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2000-04-12 19:17:23 +02:00
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* and should not be processed again at the level of {1 2 3}.) Therefore,
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2000-02-07 05:41:04 +01:00
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* the restrictinfo list in the join case appears in individual JoinPaths
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* (field joinrestrictinfo), not in the parent relation. But it's OK for
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* the RelOptInfo to store the joininfo lists, because those are the same
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* for a given rel no matter how we form it.
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2000-02-15 21:49:31 +01:00
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*
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* We store baserestrictcost in the RelOptInfo (for base relations) because
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* we know we will need it at least once (to price the sequential scan)
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* and may need it multiple times to price index scans.
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2000-09-12 23:07:18 +02:00
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*
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* outerjoinset is used to ensure correct placement of WHERE clauses that
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* apply to outer-joined relations; we must not apply such WHERE clauses
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* until after the outer join is performed.
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2000-09-29 20:21:41 +02:00
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*----------
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1996-08-28 03:59:28 +02:00
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*/
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1998-07-18 06:22:52 +02:00
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typedef struct RelOptInfo
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1997-09-07 07:04:48 +02:00
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{
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1997-09-08 04:41:22 +02:00
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NodeTag type;
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1997-09-07 07:04:48 +02:00
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1999-08-16 04:17:58 +02:00
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/* all relations included in this RelOptInfo */
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2000-04-12 19:17:23 +02:00
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Relids relids; /* integer list of base relids (RT
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* indexes) */
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1999-08-16 04:17:58 +02:00
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2000-01-09 01:26:47 +01:00
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/* size estimates generated by planner */
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double rows; /* estimated number of result tuples */
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int width; /* estimated avg width of result tuples */
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1997-09-07 07:04:48 +02:00
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/* materialization information */
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1997-09-08 04:41:22 +02:00
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List *targetlist;
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1999-02-04 02:47:02 +01:00
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List *pathlist; /* Path structures */
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2000-02-15 21:49:31 +01:00
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struct Path *cheapest_startup_path;
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struct Path *cheapest_total_path;
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1997-09-08 04:41:22 +02:00
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bool pruneable;
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1997-09-07 07:04:48 +02:00
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2000-09-29 20:21:41 +02:00
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/* information about a base rel (not set for join rels!) */
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bool issubquery;
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2000-01-09 01:26:47 +01:00
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bool indexed;
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long pages;
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double tuples;
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2000-09-29 20:21:41 +02:00
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struct Plan *subplan;
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1997-09-07 07:04:48 +02:00
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/* used by various scans and joins: */
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2000-04-12 19:17:23 +02:00
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List *baserestrictinfo; /* RestrictInfo structures (if
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* base rel) */
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Cost baserestrictcost; /* cost of evaluating the above */
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2000-09-12 23:07:18 +02:00
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Relids outerjoinset; /* integer list of base relids */
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1999-02-04 02:47:02 +01:00
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List *joininfo; /* JoinInfo structures */
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1999-08-16 04:17:58 +02:00
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List *innerjoin; /* potential indexscans for nestloop joins */
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2000-04-12 19:17:23 +02:00
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/*
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* innerjoin indexscans are not in the main pathlist because they are
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1999-08-16 04:17:58 +02:00
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* not usable except in specific join contexts; we have to test before
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* seeing whether they can be used.
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*/
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1999-05-26 00:43:53 +02:00
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} RelOptInfo;
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1997-09-07 07:04:48 +02:00
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2000-01-09 01:26:47 +01:00
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/*
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* IndexOptInfo
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* Per-index information for planning/optimization
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*
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* Prior to Postgres 7.0, RelOptInfo was used to describe both relations
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* and indexes, but that created confusion without actually doing anything
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* useful. So now we have a separate IndexOptInfo struct for indexes.
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*
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* indexoid - OID of the index relation itself
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* pages - number of disk pages in index
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* tuples - number of index tuples in index
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* classlist - List of PG_AMOPCLASS OIDs for the index
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* indexkeys - List of base-relation attribute numbers that are index keys
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* ordering - List of PG_OPERATOR OIDs which order the indexscan result
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* relam - the OID of the pg_am of the index
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2000-01-23 00:50:30 +01:00
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* amcostestimate - OID of the relam's cost estimator
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2000-04-12 19:17:23 +02:00
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* indproc - OID of the function if a functional index, else 0
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* indpred - index predicate if a partial index, else NULL
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2000-02-15 21:49:31 +01:00
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* lossy - true if index is lossy (may return non-matching tuples)
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2000-01-09 01:26:47 +01:00
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*
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* NB. the last element of the arrays classlist, indexkeys and ordering
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* is always 0.
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*/
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typedef struct IndexOptInfo
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{
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NodeTag type;
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Oid indexoid; /* OID of the index relation */
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/* statistics from pg_class */
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long pages;
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double tuples;
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/* index descriptor information */
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Oid *classlist; /* classes of AM operators */
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int *indexkeys; /* keys over which we're indexing */
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Oid *ordering; /* OIDs of sort operators for each key */
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Oid relam; /* OID of the access method (in pg_am) */
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2000-04-12 19:17:23 +02:00
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RegProcedure amcostestimate;/* OID of the access method's cost fcn */
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2000-01-23 00:50:30 +01:00
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2000-01-09 01:26:47 +01:00
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Oid indproc; /* if a functional index */
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List *indpred; /* if a partial index */
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2000-02-15 21:49:31 +01:00
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bool lossy; /* if a lossy index */
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2000-01-09 01:26:47 +01:00
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} IndexOptInfo;
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1999-08-16 04:17:58 +02:00
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/*
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* PathKeys
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*
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* The sort ordering of a path is represented by a list of sublists of
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2000-04-12 19:17:23 +02:00
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* PathKeyItem nodes. An empty list implies no known ordering. Otherwise
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1999-08-16 04:17:58 +02:00
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* the first sublist represents the primary sort key, the second the
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2000-04-12 19:17:23 +02:00
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* first secondary sort key, etc. Each sublist contains one or more
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1999-08-16 04:17:58 +02:00
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* PathKeyItem nodes, each of which can be taken as the attribute that
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2000-04-12 19:17:23 +02:00
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* appears at that sort position. (See the top of optimizer/path/pathkeys.c
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1999-08-16 04:17:58 +02:00
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* for more information.)
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*/
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1997-09-07 07:04:48 +02:00
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1999-08-16 04:17:58 +02:00
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typedef struct PathKeyItem
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1997-09-07 07:04:48 +02:00
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{
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1997-09-08 04:41:22 +02:00
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NodeTag type;
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1997-09-07 07:04:48 +02:00
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1999-08-16 04:17:58 +02:00
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Node *key; /* the item that is ordered */
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Oid sortop; /* the ordering operator ('<' op) */
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2000-04-12 19:17:23 +02:00
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1999-08-16 04:17:58 +02:00
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/*
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2000-04-12 19:17:23 +02:00
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* key typically points to a Var node, ie a relation attribute, but it
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* can also point to a Func clause representing the value indexed by a
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* functional index. Someday we might allow arbitrary expressions as
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* path keys, so don't assume more than you must.
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1999-08-16 04:17:58 +02:00
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*/
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} PathKeyItem;
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1999-02-09 04:51:42 +01:00
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1999-08-16 04:17:58 +02:00
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/*
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* Type "Path" is used as-is for sequential-scan paths. For other
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* path types it is the first component of a larger struct.
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*/
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1997-09-07 07:04:48 +02:00
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typedef struct Path
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{
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1997-09-08 04:41:22 +02:00
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NodeTag type;
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1997-09-07 07:04:48 +02:00
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1999-08-16 04:17:58 +02:00
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RelOptInfo *parent; /* the relation this path can build */
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1997-09-07 07:04:48 +02:00
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2000-02-15 21:49:31 +01:00
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/* estimated execution costs for path (see costsize.c for more info) */
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2000-04-12 19:17:23 +02:00
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Cost startup_cost; /* cost expended before fetching any
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* tuples */
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Cost total_cost; /* total cost (assuming all tuples
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* fetched) */
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1997-09-07 07:04:48 +02:00
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1999-08-16 04:17:58 +02:00
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NodeTag pathtype; /* tag identifying scan/join method */
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/* XXX why is pathtype separate from the NodeTag? */
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1997-09-07 07:04:48 +02:00
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1999-08-16 04:17:58 +02:00
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List *pathkeys; /* sort ordering of path's output */
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/* pathkeys is a List of Lists of PathKeyItem nodes; see above */
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1997-09-08 23:56:23 +02:00
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} Path;
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1997-09-07 07:04:48 +02:00
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1999-07-25 01:21:14 +02:00
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/*----------
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2000-04-12 19:17:23 +02:00
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|
|
* IndexPath represents an index scan. Although an indexscan can only read
|
1999-07-25 01:21:14 +02:00
|
|
|
* a single relation, it can scan it more than once, potentially using a
|
|
|
|
* different index during each scan. The result is the union (OR) of all the
|
2000-04-12 19:17:23 +02:00
|
|
|
* tuples matched during any scan. (The executor is smart enough not to return
|
1999-07-25 01:21:14 +02:00
|
|
|
* the same tuple more than once, even if it is matched in multiple scans.)
|
1999-08-16 04:17:58 +02:00
|
|
|
*
|
1999-07-25 01:21:14 +02:00
|
|
|
* 'indexid' is a list of index relation OIDs, one per scan to be performed.
|
2000-02-15 21:49:31 +01:00
|
|
|
*
|
1999-07-25 01:21:14 +02:00
|
|
|
* 'indexqual' is a list of index qualifications, also one per scan.
|
|
|
|
* Each entry in 'indexqual' is a sublist of qualification expressions with
|
1999-08-16 04:17:58 +02:00
|
|
|
* implicit AND semantics across the sublist items. Only expressions that
|
|
|
|
* are usable as indexquals (as determined by indxpath.c) may appear here.
|
1999-07-25 01:21:14 +02:00
|
|
|
* NOTE that the semantics of the top-level list in 'indexqual' is OR
|
|
|
|
* combination, while the sublists are implicitly AND combinations!
|
2000-02-19 00:47:31 +01:00
|
|
|
* Also note that indexquals lists do not contain RestrictInfo nodes,
|
|
|
|
* just bare clause expressions.
|
2000-02-15 21:49:31 +01:00
|
|
|
*
|
|
|
|
* 'indexscandir' is one of:
|
|
|
|
* ForwardScanDirection: forward scan of an ordered index
|
|
|
|
* BackwardScanDirection: backward scan of an ordered index
|
|
|
|
* NoMovementScanDirection: scan of an unordered index, or don't care
|
|
|
|
* (The executor doesn't care whether it gets ForwardScanDirection or
|
|
|
|
* NoMovementScanDirection for an indexscan, but the planner wants to
|
|
|
|
* distinguish ordered from unordered indexes for building pathkeys.)
|
|
|
|
*
|
|
|
|
* 'joinrelids' is only used in IndexPaths that are constructed for use
|
|
|
|
* as the inner path of a nestloop join. These paths have indexquals
|
|
|
|
* that refer to values of other rels, so those other rels must be
|
|
|
|
* included in the outer joinrel in order to make a usable join.
|
2000-03-22 23:08:35 +01:00
|
|
|
*
|
2000-09-12 23:07:18 +02:00
|
|
|
* 'alljoinquals' is also used only for inner paths of nestloop joins.
|
2000-09-29 20:21:41 +02:00
|
|
|
* This flag is TRUE iff all the indexquals came from non-pushed-down
|
|
|
|
* JOIN/ON conditions, which means the path is safe to use for an outer join.
|
2000-09-12 23:07:18 +02:00
|
|
|
*
|
2000-03-22 23:08:35 +01:00
|
|
|
* 'rows' is the estimated result tuple count for the indexscan. This
|
|
|
|
* is the same as path.parent->rows for a simple indexscan, but it is
|
|
|
|
* different for a nestloop inner path, because the additional indexquals
|
|
|
|
* coming from join clauses make the scan more selective than the parent
|
|
|
|
* rel's restrict clauses alone would do.
|
1999-07-25 01:21:14 +02:00
|
|
|
*----------
|
|
|
|
*/
|
1997-09-07 07:04:48 +02:00
|
|
|
typedef struct IndexPath
|
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
Path path;
|
|
|
|
List *indexid;
|
|
|
|
List *indexqual;
|
2000-02-15 21:49:31 +01:00
|
|
|
ScanDirection indexscandir;
|
2000-03-22 23:08:35 +01:00
|
|
|
Relids joinrelids; /* other rels mentioned in indexqual */
|
2000-09-12 23:07:18 +02:00
|
|
|
bool alljoinquals; /* all indexquals derived from JOIN conds? */
|
2000-03-22 23:08:35 +01:00
|
|
|
double rows; /* estimated number of result tuples */
|
1997-09-08 23:56:23 +02:00
|
|
|
} IndexPath;
|
1997-09-07 07:04:48 +02:00
|
|
|
|
2000-11-12 01:37:02 +01:00
|
|
|
/*
|
|
|
|
* TidPath represents a scan by TID
|
|
|
|
*/
|
1999-11-23 21:07:06 +01:00
|
|
|
typedef struct TidPath
|
|
|
|
{
|
2000-04-12 19:17:23 +02:00
|
|
|
Path path;
|
|
|
|
List *tideval;
|
|
|
|
Relids unjoined_relids;/* some rels not yet part of my Path */
|
|
|
|
} TidPath;
|
1999-11-23 21:07:06 +01:00
|
|
|
|
2000-11-12 01:37:02 +01:00
|
|
|
/*
|
|
|
|
* AppendPath represents an Append plan, ie, successive execution of
|
|
|
|
* several member plans. Currently it is only used to handle expansion
|
|
|
|
* of inheritance trees.
|
|
|
|
*/
|
|
|
|
typedef struct AppendPath
|
|
|
|
{
|
|
|
|
Path path;
|
|
|
|
List *subpaths; /* list of component Paths */
|
|
|
|
} AppendPath;
|
|
|
|
|
1999-08-16 04:17:58 +02:00
|
|
|
/*
|
|
|
|
* All join-type paths share these fields.
|
|
|
|
*/
|
|
|
|
|
|
|
|
typedef struct JoinPath
|
1997-09-07 07:04:48 +02:00
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
Path path;
|
1997-09-07 07:04:48 +02:00
|
|
|
|
2000-09-12 23:07:18 +02:00
|
|
|
JoinType jointype;
|
|
|
|
|
1999-08-16 04:17:58 +02:00
|
|
|
Path *outerjoinpath; /* path for the outer side of the join */
|
|
|
|
Path *innerjoinpath; /* path for the inner side of the join */
|
2000-09-12 23:07:18 +02:00
|
|
|
|
2000-04-12 19:17:23 +02:00
|
|
|
List *joinrestrictinfo; /* RestrictInfos to apply to join */
|
|
|
|
|
|
|
|
/*
|
|
|
|
* See the notes for RelOptInfo to understand why joinrestrictinfo is
|
2000-02-07 05:41:04 +01:00
|
|
|
* needed in JoinPath, and can't be merged into the parent RelOptInfo.
|
|
|
|
*/
|
1999-08-16 04:17:58 +02:00
|
|
|
} JoinPath;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* A nested-loop path needs no special fields.
|
|
|
|
*/
|
|
|
|
|
|
|
|
typedef JoinPath NestPath;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* A mergejoin path has these fields.
|
|
|
|
*
|
2000-02-19 00:47:31 +01:00
|
|
|
* path_mergeclauses lists the clauses (in the form of RestrictInfos)
|
2000-04-12 19:17:23 +02:00
|
|
|
* that will be used in the merge. (Before 7.0, this was a list of
|
2000-02-19 00:47:31 +01:00
|
|
|
* bare clause expressions, but we can save on list memory by leaving
|
|
|
|
* it in the form of a RestrictInfo list.)
|
|
|
|
*
|
1999-08-16 04:17:58 +02:00
|
|
|
* Note that the mergeclauses are a subset of the parent relation's
|
|
|
|
* restriction-clause list. Any join clauses that are not mergejoinable
|
|
|
|
* appear only in the parent's restrict list, and must be checked by a
|
|
|
|
* qpqual at execution time.
|
2000-02-19 00:47:31 +01:00
|
|
|
*
|
|
|
|
* outersortkeys (resp. innersortkeys) is NIL if the outer path
|
|
|
|
* (resp. inner path) is already ordered appropriately for the
|
|
|
|
* mergejoin. If it is not NIL then it is a PathKeys list describing
|
|
|
|
* the ordering that must be created by an explicit sort step.
|
1999-08-16 04:17:58 +02:00
|
|
|
*/
|
1999-02-12 18:25:05 +01:00
|
|
|
|
1997-09-07 07:04:48 +02:00
|
|
|
typedef struct MergePath
|
|
|
|
{
|
1999-02-12 18:25:05 +01:00
|
|
|
JoinPath jpath;
|
2000-04-12 19:17:23 +02:00
|
|
|
List *path_mergeclauses; /* join clauses to be used for
|
|
|
|
* merge */
|
2000-02-19 00:47:31 +01:00
|
|
|
List *outersortkeys; /* keys for explicit sort, if any */
|
|
|
|
List *innersortkeys; /* keys for explicit sort, if any */
|
1997-09-08 23:56:23 +02:00
|
|
|
} MergePath;
|
1997-09-07 07:04:48 +02:00
|
|
|
|
1999-02-22 20:55:44 +01:00
|
|
|
/*
|
1999-08-16 04:17:58 +02:00
|
|
|
* A hashjoin path has these fields.
|
|
|
|
*
|
|
|
|
* The remarks above for mergeclauses apply for hashclauses as well.
|
2000-02-19 00:47:31 +01:00
|
|
|
* (But note that path_hashclauses will always be a one-element list,
|
|
|
|
* since we only hash on one hashable clause.)
|
|
|
|
*
|
|
|
|
* Hashjoin does not care what order its inputs appear in, so we have
|
|
|
|
* no need for sortkeys.
|
1999-02-22 20:55:44 +01:00
|
|
|
*/
|
1996-08-28 03:59:28 +02:00
|
|
|
|
1999-08-16 04:17:58 +02:00
|
|
|
typedef struct HashPath
|
1997-09-07 07:04:48 +02:00
|
|
|
{
|
1999-08-16 04:17:58 +02:00
|
|
|
JoinPath jpath;
|
2000-04-12 19:17:23 +02:00
|
|
|
List *path_hashclauses; /* join clauses used for hashing */
|
1999-08-16 04:17:58 +02:00
|
|
|
} HashPath;
|
1996-08-28 03:59:28 +02:00
|
|
|
|
1999-02-22 20:55:44 +01:00
|
|
|
/*
|
1999-07-25 01:21:14 +02:00
|
|
|
* Restriction clause info.
|
1999-08-16 04:17:58 +02:00
|
|
|
*
|
1999-07-25 01:21:14 +02:00
|
|
|
* We create one of these for each AND sub-clause of a restriction condition
|
2000-09-29 20:21:41 +02:00
|
|
|
* (WHERE or JOIN/ON clause). Since the restriction clauses are logically
|
|
|
|
* ANDed, we can use any one of them or any subset of them to filter out
|
|
|
|
* tuples, without having to evaluate the rest. The RestrictInfo node itself
|
|
|
|
* stores data used by the optimizer while choosing the best query plan.
|
1999-08-16 04:17:58 +02:00
|
|
|
*
|
2000-02-07 05:41:04 +01:00
|
|
|
* If a restriction clause references a single base relation, it will appear
|
|
|
|
* in the baserestrictinfo list of the RelOptInfo for that base rel.
|
1999-08-16 04:17:58 +02:00
|
|
|
*
|
2000-02-07 05:41:04 +01:00
|
|
|
* If a restriction clause references more than one base rel, it will
|
|
|
|
* appear in the JoinInfo lists of every RelOptInfo that describes a strict
|
1999-08-16 04:17:58 +02:00
|
|
|
* subset of the base rels mentioned in the clause. The JoinInfo lists are
|
|
|
|
* used to drive join tree building by selecting plausible join candidates.
|
2000-02-07 05:41:04 +01:00
|
|
|
* The clause cannot actually be applied until we have built a join rel
|
|
|
|
* containing all the base rels it references, however.
|
|
|
|
*
|
2000-09-12 23:07:18 +02:00
|
|
|
* When we construct a join rel that includes all the base rels referenced
|
|
|
|
* in a multi-relation restriction clause, we place that clause into the
|
|
|
|
* joinrestrictinfo lists of paths for the join rel, if neither left nor
|
|
|
|
* right sub-path includes all base rels referenced in the clause. The clause
|
|
|
|
* will be applied at that join level, and will not propagate any further up
|
|
|
|
* the join tree. (Note: the "predicate migration" code was once intended to
|
2000-02-07 05:41:04 +01:00
|
|
|
* push restriction clauses up and down the plan tree based on evaluation
|
|
|
|
* costs, but it's dead code and is unlikely to be resurrected in the
|
|
|
|
* foreseeable future.)
|
|
|
|
*
|
|
|
|
* Note that in the presence of more than two rels, a multi-rel restriction
|
|
|
|
* might reach different heights in the join tree depending on the join
|
|
|
|
* sequence we use. So, these clauses cannot be associated directly with
|
|
|
|
* the join RelOptInfo, but must be kept track of on a per-join-path basis.
|
1999-08-16 04:17:58 +02:00
|
|
|
*
|
2000-09-29 20:21:41 +02:00
|
|
|
* When dealing with outer joins we have to be very careful about pushing qual
|
|
|
|
* clauses up and down the tree. An outer join's own JOIN/ON conditions must
|
|
|
|
* be evaluated exactly at that join node, and any quals appearing in WHERE or
|
|
|
|
* in a JOIN above the outer join cannot be pushed down below the outer join.
|
|
|
|
* Otherwise the outer join will produce wrong results because it will see the
|
|
|
|
* wrong sets of input rows. All quals are stored as RestrictInfo nodes
|
|
|
|
* during planning, but there's a flag to indicate whether a qual has been
|
|
|
|
* pushed down to a lower level than its original syntactic placement in the
|
|
|
|
* join tree would suggest. If an outer join prevents us from pushing a qual
|
|
|
|
* down to its "natural" semantic level (the level associated with just the
|
|
|
|
* base rels used in the qual) then the qual will appear in JoinInfo lists
|
|
|
|
* that reference more than just the base rels it actually uses. By
|
|
|
|
* pretending that the qual references all the rels appearing in the outer
|
|
|
|
* join, we prevent it from being evaluated below the outer join's joinrel.
|
|
|
|
* When we do form the outer join's joinrel, we still need to distinguish
|
|
|
|
* those quals that are actually in that join's JOIN/ON condition from those
|
|
|
|
* that appeared higher in the tree and were pushed down to the join rel
|
|
|
|
* because they used no other rels. That's what the ispusheddown flag is for;
|
|
|
|
* it tells us that a qual came from a point above the join of the specific
|
|
|
|
* set of base rels that it uses (or that the JoinInfo structures claim it
|
|
|
|
* uses). A clause that originally came from WHERE will *always* have its
|
|
|
|
* ispusheddown flag set; a clause that came from an INNER JOIN condition,
|
|
|
|
* but doesn't use all the rels being joined, will also have ispusheddown set
|
|
|
|
* because it will get attached to some lower joinrel.
|
|
|
|
*
|
2000-04-12 19:17:23 +02:00
|
|
|
* In general, the referenced clause might be arbitrarily complex. The
|
1999-08-16 04:17:58 +02:00
|
|
|
* kinds of clauses we can handle as indexscan quals, mergejoin clauses,
|
|
|
|
* or hashjoin clauses are fairly limited --- the code for each kind of
|
|
|
|
* path is responsible for identifying the restrict clauses it can use
|
|
|
|
* and ignoring the rest. Clauses not implemented by an indexscan,
|
2000-09-12 23:07:18 +02:00
|
|
|
* mergejoin, or hashjoin will be placed in the plan qual or joinqual field
|
|
|
|
* of the final Plan node, where they will be enforced by general-purpose
|
1999-08-16 04:17:58 +02:00
|
|
|
* qual-expression-evaluation code. (But we are still entitled to count
|
|
|
|
* their selectivity when estimating the result tuple count, if we
|
|
|
|
* can guess what it is...)
|
1999-02-22 20:55:44 +01:00
|
|
|
*/
|
1996-08-28 03:59:28 +02:00
|
|
|
|
1999-02-03 21:15:53 +01:00
|
|
|
typedef struct RestrictInfo
|
1997-09-07 07:04:48 +02:00
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
NodeTag type;
|
1997-09-07 07:04:48 +02:00
|
|
|
|
2000-09-12 23:07:18 +02:00
|
|
|
Expr *clause; /* the represented clause of WHERE or JOIN */
|
|
|
|
|
2000-09-29 20:21:41 +02:00
|
|
|
bool ispusheddown; /* TRUE if clause was pushed down in level */
|
1997-09-07 07:04:48 +02:00
|
|
|
|
1999-08-16 04:17:58 +02:00
|
|
|
/* only used if clause is an OR clause: */
|
2000-04-12 19:17:23 +02:00
|
|
|
List *subclauseindices; /* indexes matching subclauses */
|
2000-01-09 01:26:47 +01:00
|
|
|
/* subclauseindices is a List of Lists of IndexOptInfos */
|
1997-09-07 07:04:48 +02:00
|
|
|
|
1999-08-16 04:17:58 +02:00
|
|
|
/* valid if clause is mergejoinable, else InvalidOid: */
|
2000-04-12 19:17:23 +02:00
|
|
|
Oid mergejoinoperator; /* copy of clause operator */
|
1999-08-16 04:17:58 +02:00
|
|
|
Oid left_sortop; /* leftside sortop needed for mergejoin */
|
|
|
|
Oid right_sortop; /* rightside sortop needed for mergejoin */
|
1997-09-07 07:04:48 +02:00
|
|
|
|
1999-08-16 04:17:58 +02:00
|
|
|
/* valid if clause is hashjoinable, else InvalidOid: */
|
2000-04-12 19:17:23 +02:00
|
|
|
Oid hashjoinoperator; /* copy of clause operator */
|
1999-08-16 04:17:58 +02:00
|
|
|
} RestrictInfo;
|
1997-09-07 07:04:48 +02:00
|
|
|
|
1999-08-16 04:17:58 +02:00
|
|
|
/*
|
|
|
|
* Join clause info.
|
|
|
|
*
|
|
|
|
* We make a list of these for each RelOptInfo, containing info about
|
|
|
|
* all the join clauses this RelOptInfo participates in. (For this
|
|
|
|
* purpose, a "join clause" is a WHERE clause that mentions both vars
|
|
|
|
* belonging to this relation and vars belonging to relations not yet
|
|
|
|
* joined to it.) We group these clauses according to the set of
|
|
|
|
* other base relations (unjoined relations) mentioned in them.
|
|
|
|
* There is one JoinInfo for each distinct set of unjoined_relids,
|
|
|
|
* and its jinfo_restrictinfo lists the clause(s) that use that set
|
|
|
|
* of other relations.
|
|
|
|
*/
|
1997-09-07 07:04:48 +02:00
|
|
|
|
1998-09-01 05:29:17 +02:00
|
|
|
typedef struct JoinInfo
|
1997-09-07 07:04:48 +02:00
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
NodeTag type;
|
2000-09-12 23:07:18 +02:00
|
|
|
Relids unjoined_relids; /* some rels not yet part of my RelOptInfo */
|
2000-04-12 19:17:23 +02:00
|
|
|
List *jinfo_restrictinfo; /* relevant RestrictInfos */
|
1999-05-26 00:43:53 +02:00
|
|
|
} JoinInfo;
|
1997-09-07 07:04:48 +02:00
|
|
|
|
1996-08-28 03:59:28 +02:00
|
|
|
/*
|
1999-05-25 18:15:34 +02:00
|
|
|
* Stream:
|
1999-02-22 20:55:44 +01:00
|
|
|
* A stream represents a root-to-leaf path in a plan tree (i.e. a tree of
|
|
|
|
* JoinPaths and Paths). The stream includes pointers to all Path nodes,
|
1999-05-25 18:15:34 +02:00
|
|
|
* as well as to any clauses that reside above Path nodes. This structure
|
1999-02-22 20:55:44 +01:00
|
|
|
* is used to make Path nodes and clauses look similar, so that Predicate
|
|
|
|
* Migration can run.
|
|
|
|
*
|
1999-08-16 04:17:58 +02:00
|
|
|
* XXX currently, Predicate Migration is dead code, and so is this node type.
|
|
|
|
* Probably should remove support for it.
|
|
|
|
*
|
1999-02-22 20:55:44 +01:00
|
|
|
* pathptr -- pointer to the current path node
|
|
|
|
* cinfo -- if NULL, this stream node referes to the path node.
|
|
|
|
* Otherwise this is a pointer to the current clause.
|
|
|
|
* clausetype -- whether cinfo is in loc_restrictinfo or pathinfo in the
|
2000-01-09 01:26:47 +01:00
|
|
|
* path node (XXX this is now used only by dead code, which is
|
|
|
|
* good because the distinction no longer exists...)
|
1999-02-22 20:55:44 +01:00
|
|
|
* upstream -- linked list pointer upwards
|
|
|
|
* downstream -- ditto, downwards
|
|
|
|
* groupup -- whether or not this node is in a group with the node upstream
|
|
|
|
* groupcost -- total cost of the group that node is in
|
|
|
|
* groupsel -- total selectivity of the group that node is in
|
|
|
|
*/
|
1996-08-28 03:59:28 +02:00
|
|
|
typedef struct Stream *StreamPtr;
|
|
|
|
|
1997-09-07 07:04:48 +02:00
|
|
|
typedef struct Stream
|
|
|
|
{
|
1997-09-08 04:41:22 +02:00
|
|
|
NodeTag type;
|
|
|
|
Path *pathptr;
|
1999-02-03 21:15:53 +01:00
|
|
|
RestrictInfo *cinfo;
|
1997-09-08 04:41:22 +02:00
|
|
|
int *clausetype;
|
1999-08-16 04:17:58 +02:00
|
|
|
StreamPtr upstream;
|
|
|
|
StreamPtr downstream;
|
1997-09-08 04:41:22 +02:00
|
|
|
bool groupup;
|
|
|
|
Cost groupcost;
|
2000-04-12 19:17:23 +02:00
|
|
|
Selectivity groupsel;
|
1997-09-08 23:56:23 +02:00
|
|
|
} Stream;
|
1997-09-07 07:04:48 +02:00
|
|
|
|
1998-09-01 06:40:42 +02:00
|
|
|
#endif /* RELATION_H */
|