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Revert: Remove useless self-joins

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This commit reverts d3d55ce571 and subsequent fixes 2b26a69455, 93c85db3b5,
b44a1708ab, b7f315c9d7, 8a8ed916f7, b5fb6736ed, 0a93f803f4, e0477837ce,
a7928a57b9, 5ef34a8fc3, 30b4955a46, 8c441c0827, 028b15405b, fe093994db,
489072ab7a, and 466979ef03.

We are quite late in the release cycle and new bugs continue to appear.  Even
though we have fixes for all known bugs, there is a risk of throwing many
bugs to end users.

The plan for self-join elimination would be to do more review and testing,
then re-commit in the early v18 cycle.

Reported-by: Tom Lane
Discussion: https://postgr.es/m/2422119.1714691974%40sss.pgh.pa.us
This commit is contained in:
Alexander Korotkov
2024-05-06 14:35:58 +03:00
parent 81b2252e60
commit d1d286d83c
14 changed files with 69 additions and 2883 deletions
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39
src/backend/optimizer/path/indxpath.c
View File

@ -3440,22 +3440,6 @@ bool
relation_has_unique_index_for(PlannerInfo *root, RelOptInfo *rel,
List *restrictlist,
List *exprlist, List *oprlist)
{
return relation_has_unique_index_ext(root, rel, restrictlist,
exprlist, oprlist, NULL);
}
/*
* relation_has_unique_index_ext
* Same as relation_has_unique_index_for(), but supports extra_clauses
* parameter. If extra_clauses isn't NULL, return baserestrictinfo clauses
* which were used to derive uniqueness.
*/
bool
relation_has_unique_index_ext(PlannerInfo *root, RelOptInfo *rel,
List *restrictlist,
List *exprlist, List *oprlist,
List **extra_clauses)
{
ListCell *ic;
@ -3511,7 +3495,6 @@ relation_has_unique_index_ext(PlannerInfo *root, RelOptInfo *rel,
{
IndexOptInfo *ind = (IndexOptInfo *) lfirst(ic);
int c;
List *exprs = NIL;
/*
* If the index is not unique, or not immediately enforced, or if it's
@ -3563,24 +3546,6 @@ relation_has_unique_index_ext(PlannerInfo *root, RelOptInfo *rel,
if (match_index_to_operand(rexpr, c, ind))
{
matched = true; /* column is unique */
if (bms_membership(rinfo->clause_relids) == BMS_SINGLETON)
{
MemoryContext oldMemCtx =
MemoryContextSwitchTo(root->planner_cxt);
/*
* Add filter clause into a list allowing caller to
* know if uniqueness have made not only by join
* clauses.
*/
Assert(bms_is_empty(rinfo->left_relids) ||
bms_is_empty(rinfo->right_relids));
if (extra_clauses)
exprs = lappend(exprs, rinfo);
MemoryContextSwitchTo(oldMemCtx);
}
break;
}
}
@ -3623,11 +3588,7 @@ relation_has_unique_index_ext(PlannerInfo *root, RelOptInfo *rel,
/* Matched all key columns of this index? */
if (c == ind->nkeycolumns)
{
if (extra_clauses)
*extra_clauses = exprs;
return true;
}
}
return false;

1284
src/backend/optimizer/plan/analyzejoins.c
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File diff suppressed because it is too large Load Diff

5
src/backend/optimizer/plan/planmain.c
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@ -230,11 +230,6 @@ query_planner(PlannerInfo *root,
*/
reduce_unique_semijoins(root);
/*
* Remove self joins on a unique column.
*/
joinlist = remove_useless_self_joins(root, joinlist);
/*
* Now distribute "placeholders" to base rels as needed. This has to be
* done after join removal because removal could change whether a