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Fix up planner infrastructure to support LATERAL properly.

Browse Source 
This patch takes care of a number of problems having to do with failure
to choose valid join orders and incorrect handling of lateral references
pulled up from subqueries.  Notable changes:

* Add a LateralJoinInfo data structure similar to SpecialJoinInfo, to
represent join ordering constraints created by lateral references.
(I first considered extending the SpecialJoinInfo structure, but the
semantics are different enough that a separate data structure seems
better.)  Extend join_is_legal() and related functions to prevent trying
to form unworkable joins, and to ensure that we will consider joins that
satisfy lateral references even if the joins would be clauseless.

* Fill in the infrastructure needed for the last few types of relation scan
paths to support parameterization.  We'd have wanted this eventually
anyway, but it is necessary now because a relation that gets pulled up out
of a UNION ALL subquery may acquire a reltargetlist containing lateral
references, meaning that its paths *have* to be parameterized whether or
not we have any code that can push join quals down into the scan.

* Compute data about lateral references early in query_planner(), and save
in RelOptInfo nodes, to avoid repetitive calculations later.

* Assorted corner-case bug fixes.

There's probably still some bugs left, but this is a lot closer to being
real than it was before.
This commit is contained in:
Tom Lane
2012-08-26 22:48:55 -04:00
parent de87d47044
commit 9ff79b9d4e
30 changed files with 818 additions and 183 deletions
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26
src/backend/optimizer/util/pathnode.c
View File

@ -902,18 +902,21 @@ create_bitmap_or_path(PlannerInfo *root,
* Creates a path corresponding to a scan by TID, returning the pathnode.
*/
TidPath *
create_tidscan_path(PlannerInfo *root, RelOptInfo *rel, List *tidquals)
create_tidscan_path(PlannerInfo *root, RelOptInfo *rel, List *tidquals,
Relids required_outer)
{
TidPath *pathnode = makeNode(TidPath);
pathnode->path.pathtype = T_TidScan;
pathnode->path.parent = rel;
pathnode->path.param_info = NULL; /* never parameterized at present */
pathnode->path.param_info = get_baserel_parampathinfo(root, rel,
required_outer);
pathnode->path.pathkeys = NIL; /* always unordered */
pathnode->tidquals = tidquals;
cost_tidscan(&pathnode->path, root, rel, tidquals);
cost_tidscan(&pathnode->path, root, rel, tidquals,
pathnode->path.param_info);
return pathnode;
}
@ -1061,7 +1064,7 @@ create_result_path(List *quals)
pathnode->path.pathtype = T_Result;
pathnode->path.parent = NULL;
pathnode->path.param_info = NULL;
pathnode->path.param_info = NULL; /* there are no other rels... */
pathnode->path.pathkeys = NIL;
pathnode->quals = quals;
@ -1711,16 +1714,17 @@ create_valuesscan_path(PlannerInfo *root, RelOptInfo *rel,
* returning the pathnode.
*/
Path *
create_ctescan_path(PlannerInfo *root, RelOptInfo *rel)
create_ctescan_path(PlannerInfo *root, RelOptInfo *rel, Relids required_outer)
{
Path *pathnode = makeNode(Path);
pathnode->pathtype = T_CteScan;
pathnode->parent = rel;
pathnode->param_info = NULL; /* never parameterized at present */
pathnode->param_info = get_baserel_parampathinfo(root, rel,
required_outer);
pathnode->pathkeys = NIL; /* XXX for now, result is always unordered */
cost_ctescan(pathnode, root, rel);
cost_ctescan(pathnode, root, rel, pathnode->param_info);
return pathnode;
}
@ -1731,17 +1735,19 @@ create_ctescan_path(PlannerInfo *root, RelOptInfo *rel)
* returning the pathnode.
*/
Path *
create_worktablescan_path(PlannerInfo *root, RelOptInfo *rel)
create_worktablescan_path(PlannerInfo *root, RelOptInfo *rel,
Relids required_outer)
{
Path *pathnode = makeNode(Path);
pathnode->pathtype = T_WorkTableScan;
pathnode->parent = rel;
pathnode->param_info = NULL; /* never parameterized at present */
pathnode->param_info = get_baserel_parampathinfo(root, rel,
required_outer);
pathnode->pathkeys = NIL; /* result is always unordered */
/* Cost is the same as for a regular CTE scan */
cost_ctescan(pathnode, root, rel);
cost_ctescan(pathnode, root, rel, pathnode->param_info);
return pathnode;
}