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Simplify and generalize PrepareSortSupportFromIndexRel()

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PrepareSortSupportFromIndexRel() was accepting btree strategy numbers
purely for the purpose of comparing it later against btree strategies
to determine if the sort direction was forward or reverse.  Change
that.  Instead, pass a bool directly, to indicate the same without an
unfortunate assumption that a strategy number refers specifically to a
btree strategy.  (This is similar in spirit to commits 0d2aa4d493 and
c594f1ad2ba.)

(This could arguably be simplfied further by having the callers fill
in ssup_reverse directly.  But this way, it preserves consistency by
having all PrepareSortSupport*() variants be responsible for filling
in ssup_reverse.)

Moreover, remove the hardcoded check against BTREE_AM_OID, and check
against amcanorder instead, which is the actual requirement.

Co-authored-by: Mark Dilger <mark.dilger@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/E72EAA49-354D-4C2E-8EB9-255197F55330@enterprisedb.com
This commit is contained in:
Peter Eisentraut
2025-03-14 10:34:08 +01:00
parent 1548c3a304
commit a359d37019
4 changed files with 16 additions and 22 deletions
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15
src/backend/utils/sort/sortsupport.c
View File

@@ -150,15 +150,15 @@ PrepareSortSupportFromOrderingOp(Oid orderingOp, SortSupport ssup)
}
/*
* Fill in SortSupport given an index relation, attribute, and strategy.
* Fill in SortSupport given an index relation and attribute.
*
* Caller must previously have zeroed the SortSupportData structure and then
* filled in ssup_cxt, ssup_attno, ssup_collation, and ssup_nulls_first. This
* will fill in ssup_reverse (based on the supplied strategy), as well as the
* will fill in ssup_reverse (based on the supplied argument), as well as the
* comparator function pointer.
*/
void
PrepareSortSupportFromIndexRel(Relation indexRel, int16 strategy,
PrepareSortSupportFromIndexRel(Relation indexRel, bool reverse,
SortSupport ssup)
{
Oid opfamily = indexRel->rd_opfamily[ssup->ssup_attno - 1];
@@ -166,12 +166,9 @@ PrepareSortSupportFromIndexRel(Relation indexRel, int16 strategy,
Assert(ssup->comparator == NULL);
if (indexRel->rd_rel->relam != BTREE_AM_OID)
elog(ERROR, "unexpected non-btree AM: %u", indexRel->rd_rel->relam);
if (strategy != BTGreaterStrategyNumber &&
strategy != BTLessStrategyNumber)
elog(ERROR, "unexpected sort support strategy: %d", strategy);
ssup->ssup_reverse = (strategy == BTGreaterStrategyNumber);
if (!indexRel->rd_indam->amcanorder)
elog(ERROR, "unexpected non-amcanorder AM: %u", indexRel->rd_rel->relam);
ssup->ssup_reverse = reverse;
FinishSortSupportFunction(opfamily, opcintype, ssup);
}

14
src/backend/utils/sort/tuplesortvariants.c
View File

@@ -329,7 +329,7 @@ tuplesort_begin_cluster(TupleDesc tupDesc,
{
SortSupport sortKey = base->sortKeys + i;
ScanKey scanKey = indexScanKey->scankeys + i;
int16 strategy;
bool reverse;
sortKey->ssup_cxt = CurrentMemoryContext;
sortKey->ssup_collation = scanKey->sk_collation;
@@ -341,10 +341,9 @@ tuplesort_begin_cluster(TupleDesc tupDesc,
Assert(sortKey->ssup_attno != 0);
strategy = (scanKey->sk_flags & SK_BT_DESC) != 0 ?
BTGreaterStrategyNumber : BTLessStrategyNumber;
reverse = (scanKey->sk_flags & SK_BT_DESC) != 0;
PrepareSortSupportFromIndexRel(indexRel, strategy, sortKey);
PrepareSortSupportFromIndexRel(indexRel, reverse, sortKey);
}
pfree(indexScanKey);
@@ -412,7 +411,7 @@ tuplesort_begin_index_btree(Relation heapRel,
{
SortSupport sortKey = base->sortKeys + i;
ScanKey scanKey = indexScanKey->scankeys + i;
int16 strategy;
bool reverse;
sortKey->ssup_cxt = CurrentMemoryContext;
sortKey->ssup_collation = scanKey->sk_collation;
@@ -424,10 +423,9 @@ tuplesort_begin_index_btree(Relation heapRel,
Assert(sortKey->ssup_attno != 0);
strategy = (scanKey->sk_flags & SK_BT_DESC) != 0 ?
BTGreaterStrategyNumber : BTLessStrategyNumber;
reverse = (scanKey->sk_flags & SK_BT_DESC) != 0;
PrepareSortSupportFromIndexRel(indexRel, strategy, sortKey);
PrepareSortSupportFromIndexRel(indexRel, reverse, sortKey);
}
pfree(indexScanKey);