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Adjust reltarget assignment for UPPERREL_PARTIAL_DISTINCT rel

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A comment in grouping_planner() claimed that the PlannerInfo
upper_targets array was not used in core code.  However, the code that
generated the paths for the UPPERREL_PARTIAL_DISTINCT rel made that
comment untrue.

Here we adjust the create_distinct_paths() function signature to pass
down the PathTarget the same as is done for create_grouping_paths(),
thus making the aforementioned comment true again.

In passing adjust the order of the upper_targets[] assignments.  These
seem to be following the reverse enum order apart from
UPPERREL_PARTIAL_DISTINCT.

Also, update the header comment for generate_gather_paths() to mention
the function is also used to create gather paths for partial distinct
paths.

Author: Richard Guo, David Rowley
Discussion: https://postgr.es/m/CAMbWs48u9VoVOouJsys1qOaC9WVGVmBa+wT1dx8KvxF5GPzezA@mail.gmail.com
This commit is contained in:
David Rowley
2024-02-07 21:22:34 +13:00
parent aa5edbe379
commit 902900b308
2 changed files with 18 additions and 12 deletions
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8
src/backend/optimizer/path/allpaths.c
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@@ -3053,10 +3053,10 @@ set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
*
* If we're generating paths for a scan or join relation, override_rows will
* be false, and we'll just use the relation's size estimate. When we're
* being called for a partially-grouped path, though, we need to override
* the rowcount estimate. (It's not clear that the particular value we're
* using here is actually best, but the underlying rel has no estimate so
* we must do something.)
* being called for a partially-grouped or partially-distinct path, though, we
* need to override the rowcount estimate. (It's not clear that the
* particular value we're using here is actually best, but the underlying rel
* has no estimate so we must do something.)
*/
void
generate_gather_paths(PlannerInfo *root, RelOptInfo *rel, bool override_rows)