relnode.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 563 行 · 第 1/2 页

/*-------------------------------------------------------------------------
 *
 * relnode.c
 *	  Relation-node lookup/construction routines
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.52.4.1 2003/12/08 18:20:10 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "optimizer/cost.h"
#include "optimizer/joininfo.h"
#include "optimizer/pathnode.h"
#include "optimizer/plancat.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/tlist.h"
#include "parser/parsetree.h"


static RelOptInfo *make_base_rel(Query *root, int relid);
static void build_joinrel_tlist(Query *root, RelOptInfo *joinrel);
static List *build_joinrel_restrictlist(Query *root,
						   RelOptInfo *joinrel,
						   RelOptInfo *outer_rel,
						   RelOptInfo *inner_rel,
						   JoinType jointype);
static void build_joinrel_joinlist(RelOptInfo *joinrel,
					   RelOptInfo *outer_rel,
					   RelOptInfo *inner_rel);
static List *subbuild_joinrel_restrictlist(RelOptInfo *joinrel,
							  List *joininfo_list);
static void subbuild_joinrel_joinlist(RelOptInfo *joinrel,
						  List *joininfo_list);


/*
 * build_base_rel
 *	  Construct a new base relation RelOptInfo, and put it in the query's
 *	  base_rel_list.
 */
void
build_base_rel(Query *root, int relid)
{
	List	   *rels;
	RelOptInfo *rel;

	/* Rel should not exist already */
	foreach(rels, root->base_rel_list)
	{
		rel = (RelOptInfo *) lfirst(rels);
		if (relid == rel->relid)
			elog(ERROR, "rel already exists");
	}

	/* It should not exist as an "other" rel, either */
	foreach(rels, root->other_rel_list)
	{
		rel = (RelOptInfo *) lfirst(rels);
		if (relid == rel->relid)
			elog(ERROR, "rel already exists as \"other\" rel");
	}

	/* No existing RelOptInfo for this base rel, so make a new one */
	rel = make_base_rel(root, relid);

	/* and add it to the list */
	root->base_rel_list = lcons(rel, root->base_rel_list);
}

/*
 * build_other_rel
 *	  Returns relation entry corresponding to 'relid', creating a new one
 *	  if necessary.  This is for 'other' relations, which are much like
 *	  base relations except that they live in a different list.
 */
RelOptInfo *
build_other_rel(Query *root, int relid)
{
	List	   *rels;
	RelOptInfo *rel;

	/* Already made? */
	foreach(rels, root->other_rel_list)
	{
		rel = (RelOptInfo *) lfirst(rels);
		if (relid == rel->relid)
			return rel;
	}

	/* It should not exist as a base rel */
	foreach(rels, root->base_rel_list)
	{
		rel = (RelOptInfo *) lfirst(rels);
		if (relid == rel->relid)
			elog(ERROR, "rel already exists as base rel");
	}

	/* No existing RelOptInfo for this other rel, so make a new one */
	rel = make_base_rel(root, relid);

	/* presently, must be an inheritance child rel */
	Assert(rel->reloptkind == RELOPT_BASEREL);
	rel->reloptkind = RELOPT_OTHER_CHILD_REL;

	/* and add it to the list */
	root->other_rel_list = lcons(rel, root->other_rel_list);

	return rel;
}

/*
 * make_base_rel
 *	  Construct a base-relation RelOptInfo for the specified rangetable index.
 *
 * Common code for build_base_rel and build_other_rel.
 */
static RelOptInfo *
make_base_rel(Query *root, int relid)
{
	RelOptInfo *rel = makeNode(RelOptInfo);
	RangeTblEntry *rte = rt_fetch(relid, root->rtable);

	rel->reloptkind = RELOPT_BASEREL;
	rel->relids = bms_make_singleton(relid);
	rel->rows = 0;
	rel->width = 0;
	FastListInit(&rel->reltargetlist);
	rel->pathlist = NIL;
	rel->cheapest_startup_path = NULL;
	rel->cheapest_total_path = NULL;
	rel->cheapest_unique_path = NULL;
	rel->pruneable = true;
	rel->relid = relid;
	rel->rtekind = rte->rtekind;
	/* min_attr, max_attr, attr_needed, attr_widths are set below */
	rel->indexlist = NIL;
	rel->pages = 0;
	rel->tuples = 0;
	rel->subplan = NULL;
	rel->baserestrictinfo = NIL;
	rel->baserestrictcost.startup = 0;
	rel->baserestrictcost.per_tuple = 0;
	rel->outerjoinset = NULL;
	rel->joininfo = NIL;
	rel->index_outer_relids = NULL;
	rel->index_inner_paths = NIL;

	/* Check type of rtable entry */
	switch (rte->rtekind)
	{
		case RTE_RELATION:
			/* Table --- retrieve statistics from the system catalogs */
			get_relation_info(rte->relid, rel);
			break;
		case RTE_SUBQUERY:
		case RTE_FUNCTION:
			/* Subquery or function --- need only set up attr range */
			/* Note: 0 is included in range to support whole-row Vars */
			rel->min_attr = 0;
			rel->max_attr = length(rte->eref->colnames);
			break;
		default:
			elog(ERROR, "unrecognized RTE kind: %d",
				 (int) rte->rtekind);
			break;
	}

	Assert(rel->max_attr >= rel->min_attr);
	rel->attr_needed = (Relids *)
		palloc0((rel->max_attr - rel->min_attr + 1) * sizeof(Relids));
	rel->attr_widths = (int32 *)
		palloc0((rel->max_attr - rel->min_attr + 1) * sizeof(int32));

	return rel;
}

/*
 * find_base_rel
 *	  Find a base or other relation entry, which must already exist
 *	  (since we'd have no idea which list to add it to).
 */
RelOptInfo *
find_base_rel(Query *root, int relid)
{
	List	   *rels;
	RelOptInfo *rel;

	foreach(rels, root->base_rel_list)
	{
		rel = (RelOptInfo *) lfirst(rels);
		if (relid == rel->relid)
			return rel;
	}

	foreach(rels, root->other_rel_list)
	{
		rel = (RelOptInfo *) lfirst(rels);
		if (relid == rel->relid)
			return rel;
	}

	elog(ERROR, "no relation entry for relid %d", relid);

	return NULL;				/* keep compiler quiet */
}

/*
 * find_join_rel
 *	  Returns relation entry corresponding to 'relids' (a set of RT indexes),
 *	  or NULL if none exists.  This is for join relations.
 *
 * Note: there is probably no good reason for this to be called from
 * anywhere except build_join_rel, but keep it as a separate routine
 * just in case.
 */
static RelOptInfo *
find_join_rel(Query *root, Relids relids)
{
	List	   *joinrels;

	foreach(joinrels, root->join_rel_list)
	{
		RelOptInfo *rel = (RelOptInfo *) lfirst(joinrels);

		if (bms_equal(rel->relids, relids))
			return rel;
	}

	return NULL;
}

/*
 * build_join_rel
 *	  Returns relation entry corresponding to the union of two given rels,
 *	  creating a new relation entry if none already exists.
 *
 * 'joinrelids' is the Relids set that uniquely identifies the join
 * 'outer_rel' and 'inner_rel' are relation nodes for the relations to be
 *		joined
 * 'jointype': type of join (inner/outer)
 * 'restrictlist_ptr': result variable.  If not NULL, *restrictlist_ptr
 *		receives the list of RestrictInfo nodes that apply to this
 *		particular pair of joinable relations.
 *
 * restrictlist_ptr makes the routine's API a little grotty, but it saves
 * duplicated calculation of the restrictlist...
 */
RelOptInfo *
build_join_rel(Query *root,
			   Relids joinrelids,
			   RelOptInfo *outer_rel,
			   RelOptInfo *inner_rel,
			   JoinType jointype,
			   List **restrictlist_ptr)
{
	RelOptInfo *joinrel;
	List	   *restrictlist;

	/*
	 * See if we already have a joinrel for this set of base rels.
	 */
	joinrel = find_join_rel(root, joinrelids);

	if (joinrel)
	{
		/*
		 * Yes, so we only need to figure the restrictlist for this
		 * particular pair of component relations.
		 */
		if (restrictlist_ptr)
			*restrictlist_ptr = build_joinrel_restrictlist(root,
														   joinrel,
														   outer_rel,
														   inner_rel,
														   jointype);
		return joinrel;