database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-08 11:42:09 +03:00
Code Activity

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
Download Patch File Download Diff File Expand all files Collapse all files

12
src/backend/optimizer/path/tidpath.c
View File

@ -249,10 +249,20 @@ TidQualFromRestrictinfo(List *restrictinfo, int varno)
void
create_tidscan_paths(PlannerInfo *root, RelOptInfo *rel)
{
Relids required_outer;
List *tidquals;
/*
* We don't support pushing join clauses into the quals of a tidscan, but
* it could still have required parameterization due to LATERAL refs in
* its tlist. (That can only happen if the tidscan is on a relation
* pulled up out of a UNION ALL appendrel.)
*/
required_outer = rel->lateral_relids;
tidquals = TidQualFromRestrictinfo(rel->baserestrictinfo, rel->relid);
if (tidquals)
add_path(rel, (Path *) create_tidscan_path(root, rel, tidquals));
add_path(rel, (Path *) create_tidscan_path(root, rel, tidquals,
required_outer));
}