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Fix possible crash in partition-wise join.

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The previous code assumed that we'd always succeed in creating
child-joins for a joinrel for which partition-wise join was considered,
but that's not guaranteed, at least in the case where dummy rels
are involved.

Ashutosh Bapat, with some wordsmithing by me.

Discussion: http://postgr.es/m/CAFjFpRf8=uyMYYfeTBjWDMs1tR5t--FgOe2vKZPULxxdYQ4RNw@mail.gmail.com
This commit is contained in:
Robert Haas
2018-02-05 17:31:57 -05:00
parent 1eb5d43bee
commit f069c91a57
6 changed files with 43 additions and 55 deletions
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18
src/backend/optimizer/path/allpaths.c
View File

@ -3425,20 +3425,8 @@ generate_partition_wise_join_paths(PlannerInfo *root, RelOptInfo *rel)
if (!IS_JOIN_REL(rel))
return;
/*
* If we've already proven this join is empty, we needn't consider any
* more paths for it.
*/
if (IS_DUMMY_REL(rel))
return;
/*
* We've nothing to do if the relation is not partitioned. An outer join
* relation which had an empty inner relation in every pair will have the
* rest of the partitioning properties set except the child-join
* RelOptInfos. See try_partition_wise_join() for more details.
*/
if (rel->nparts <= 0 || rel->part_rels == NULL)
/* We've nothing to do if the relation is not partitioned. */
if (!IS_PARTITIONED_REL(rel))
return;
/* Guard against stack overflow due to overly deep partition hierarchy. */
@ -3452,6 +3440,8 @@ generate_partition_wise_join_paths(PlannerInfo *root, RelOptInfo *rel)
{
RelOptInfo *child_rel = part_rels[cnt_parts];
Assert(child_rel != NULL);
/* Add partition-wise join paths for partitioned child-joins. */
generate_partition_wise_join_paths(root, child_rel);

16
src/backend/optimizer/path/joinrels.c
View File

@ -1318,17 +1318,6 @@ try_partition_wise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
if (!IS_PARTITIONED_REL(joinrel))
return;
/*
* set_rel_pathlist() may not create paths in children of an empty
* partitioned table and so we can not add paths to child-joins. So, deem
* such a join as unpartitioned. When a partitioned relation is deemed
* empty because all its children are empty, dummy path will be set in
* each of the children. In such a case we could still consider the join
* as partitioned, but it might not help much.
*/
if (IS_DUMMY_REL(rel1) || IS_DUMMY_REL(rel2))
return;
/*
* Since this join relation is partitioned, all the base relations
* participating in this join must be partitioned and so are all the
@ -1360,11 +1349,6 @@ try_partition_wise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
nparts = joinrel->nparts;
/* Allocate space to hold child-joins RelOptInfos, if not already done. */
if (!joinrel->part_rels)
joinrel->part_rels =
(RelOptInfo **) palloc0(sizeof(RelOptInfo *) * nparts);
/*
* Create child-join relations for this partitioned join, if those don't
* exist. Add paths to child-joins for a pair of child relations