Simplify and generalize PrepareSortSupportFromIndexRel()

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 0d2aa4d4937 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

diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c
index fa336ba00963808e06e69ad26480d2c340bd2282..3794cc924ad467366db61e75d07fb286c86ef6cb 100644 (file)
--- a/src/backend/access/nbtree/nbtsort.c
+++ b/src/backend/access/nbtree/nbtsort.c
@@ -1171,7 +1171,7 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2)
        {
            SortSupport sortKey = sortKeys + i;
            ScanKey     scanKey = wstate->inskey->scankeys + i;
-           int16       strategy;
+           bool        reverse;
 
            sortKey->ssup_cxt = CurrentMemoryContext;
            sortKey->ssup_collation = scanKey->sk_collation;
@@ -1183,10 +1183,9 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2)
 
            Assert(sortKey->ssup_attno != 0);
 
-           strategy = (scanKey->sk_flags & SK_BT_DESC) != 0 ?
-               BTGreaterStrategyNumber : BTLessStrategyNumber;
+           reverse = (scanKey->sk_flags & SK_BT_DESC) != 0;
 
-           PrepareSortSupportFromIndexRel(wstate->index, strategy, sortKey);
+           PrepareSortSupportFromIndexRel(wstate->index, reverse, sortKey);
        }
 
        for (;;)

diff --git a/src/backend/utils/sort/sortsupport.c b/src/backend/utils/sort/sortsupport.c
index 6037031eaa3979543de94baa65ff8a03aca55e8c..0b4f08ed2ec50f1fd464b1bcbe23ba353aebfc08 100644 (file)
--- a/src/backend/utils/sort/sortsupport.c
+++ b/src/backend/utils/sort/sortsupport.c
@@ -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);
 }

diff --git a/src/backend/utils/sort/tuplesortvariants.c b/src/backend/utils/sort/tuplesortvariants.c
index eb8601e22573b009849cd09685249f4ce3959127..4059af5bb7189b7a6fd795c579b34e8b760caeef 100644 (file)
--- a/src/backend/utils/sort/tuplesortvariants.c
+++ b/src/backend/utils/sort/tuplesortvariants.c
@@ -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);

diff --git a/src/include/utils/sortsupport.h b/src/include/utils/sortsupport.h
index 51200db8ae95fa8232b353b3c04889cf16d88c84..b7abaf7802de0c63631c422d5ec05f6dff00b268 100644 (file)
--- a/src/include/utils/sortsupport.h
+++ b/src/include/utils/sortsupport.h
@@ -384,7 +384,7 @@ extern int  ssup_datum_int32_cmp(Datum x, Datum y, SortSupport ssup);
 /* Other functions in utils/sort/sortsupport.c */
 extern void PrepareSortSupportComparisonShim(Oid cmpFunc, SortSupport ssup);
 extern void PrepareSortSupportFromOrderingOp(Oid orderingOp, SortSupport ssup);
-extern void PrepareSortSupportFromIndexRel(Relation indexRel, int16 strategy,
+extern void PrepareSortSupportFromIndexRel(Relation indexRel, bool reverse,
                                           SortSupport ssup);
 extern void PrepareSortSupportFromGistIndexRel(Relation indexRel, SortSupport ssup);