database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-15 19:21:59 +03:00
Code Activity

Teach planner how to rearrange join order for some classes of OUTER JOIN.

Browse Source 
Per my recent proposal.  I ended up basing the implementation on the
existing mechanism for enforcing valid join orders of IN joins --- the
rules for valid outer-join orders are somewhat similar.
This commit is contained in:
Tom Lane
2005-12-20 02:30:36 +00:00
parent 1a6aaaa6c4
commit e3b9852728
23 changed files with 969 additions and 722 deletions
Download Patch File Download Diff File Expand all files Collapse all files

62
src/backend/optimizer/path/allpaths.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.138 2005/11/22 18:17:12 momjian Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.139 2005/12/20 02:30:35 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -51,6 +51,7 @@ static void set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
Index rti, RangeTblEntry *rte);
static void set_function_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static RelOptInfo *make_rel_from_joinlist(PlannerInfo *root, List *joinlist);
static RelOptInfo *make_one_rel_by_joins(PlannerInfo *root, int levels_needed,
List *initial_rels);
static bool subquery_is_pushdown_safe(Query *subquery, Query *topquery,
@ -73,7 +74,7 @@ static void recurse_push_qual(Node *setOp, Query *topquery,
* single rel that represents the join of all base rels in the query.
*/
RelOptInfo *
make_one_rel(PlannerInfo *root)
make_one_rel(PlannerInfo *root, List *joinlist)
{
RelOptInfo *rel;
@ -85,10 +86,7 @@ make_one_rel(PlannerInfo *root)
/*
* Generate access paths for the entire join tree.
*/
Assert(root->parse->jointree != NULL &&
IsA(root->parse->jointree, FromExpr));
rel = make_fromexpr_rel(root, root->parse->jointree);
rel = make_rel_from_joinlist(root, joinlist);
/*
* The result should join all and only the query's base rels.
@ -528,43 +526,65 @@ set_function_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
}
/*
* make_fromexpr_rel
* Build access paths for a FromExpr jointree node.
* make_rel_from_joinlist
* Build access paths using a "joinlist" to guide the join path search.
*
* See comments for deconstruct_jointree() for definition of the joinlist
* data structure.
*/
RelOptInfo *
make_fromexpr_rel(PlannerInfo *root, FromExpr *from)
static RelOptInfo *
make_rel_from_joinlist(PlannerInfo *root, List *joinlist)
{
int levels_needed;
List *initial_rels = NIL;
ListCell *jt;
List *initial_rels;
ListCell *jl;
/*
* Count the number of child jointree nodes. This is the depth of the
* Count the number of child joinlist nodes. This is the depth of the
* dynamic-programming algorithm we must employ to consider all ways of
* joining the child nodes.
*/
levels_needed = list_length(from->fromlist);
levels_needed = list_length(joinlist);
if (levels_needed <= 0)
return NULL; /* nothing to do? */
/*
* Construct a list of rels corresponding to the child jointree nodes.
* Construct a list of rels corresponding to the child joinlist nodes.
* This may contain both base rels and rels constructed according to
* explicit JOIN directives.
* sub-joinlists.
*/
foreach(jt, from->fromlist)
initial_rels = NIL;
foreach(jl, joinlist)
{
Node *jtnode = (Node *) lfirst(jt);
Node *jlnode = (Node *) lfirst(jl);
RelOptInfo *thisrel;
initial_rels = lappend(initial_rels,
make_jointree_rel(root, jtnode));
if (IsA(jlnode, RangeTblRef))
{
int varno = ((RangeTblRef *) jlnode)->rtindex;
thisrel = find_base_rel(root, varno);
}
else if (IsA(jlnode, List))
{
/* Recurse to handle subproblem */
thisrel = make_rel_from_joinlist(root, (List *) jlnode);
}
else
{
elog(ERROR, "unrecognized joinlist node type: %d",
(int) nodeTag(jlnode));
thisrel = NULL; /* keep compiler quiet */
}
initial_rels = lappend(initial_rels, thisrel);
}
if (levels_needed == 1)
{
/*
* Single jointree node, so we're done.
* Single joinlist node, so we're done.
*/
return (RelOptInfo *) linitial(initial_rels);
}