Fix tuplesort optimization for CLUSTER-on-expression.

When dispatching sort operations to specialized variants, commit
69749243 failed to handle the case where CLUSTER-sort decides not to
initialize datum1 and isnull1.  Fix by hoisting that decision up a level
and advertising whether datum1 can be relied on, in the Tuplesortstate
object.

Per reports from UBsan and Valgrind build farm animals, while running
the cluster.sql test.

Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CAFBsxsF1TeK5Fic0M%2BTSJXzbKsY6aBqJGNj6ptURuB09ZF6k_w%40mail.gmail.com

diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 361527098f94b34045872b83ae429df9b632d0a9..10676299dc86533b2ca825ada0b794b641809a38 100644 (file)
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -306,6 +306,12 @@ struct Tuplesortstate
    void        (*readtup) (Tuplesortstate *state, SortTuple *stup,
                            LogicalTape *tape, unsigned int len);
 
+   /*
+    * Whether SortTuple's datum1 and isnull1 members are maintained by the
+    * above routines.  If not, some sort specializations are disabled.
+    */
+   bool        haveDatum1;
+
    /*
     * This array holds the tuples now in sort memory.  If we are in state
     * INITIAL, the tuples are in no particular order; if we are in state
@@ -1016,6 +1022,7 @@ tuplesort_begin_heap(TupleDesc tupDesc,
    state->copytup = copytup_heap;
    state->writetup = writetup_heap;
    state->readtup = readtup_heap;
+   state->haveDatum1 = true;
 
    state->tupDesc = tupDesc;   /* assume we need not copy tupDesc */
    state->abbrevNext = 10;
@@ -1095,6 +1102,15 @@ tuplesort_begin_cluster(TupleDesc tupDesc,
 
    state->indexInfo = BuildIndexInfo(indexRel);
 
+   /*
+    * If we don't have a simple leading attribute, we don't currently
+    * initialize datum1, so disable optimizations that require it.
+    */
+   if (state->indexInfo->ii_IndexAttrNumbers[0] == 0)
+       state->haveDatum1 = false;
+   else
+       state->haveDatum1 = true;
+
    state->tupDesc = tupDesc;   /* assume we need not copy tupDesc */
 
    indexScanKey = _bt_mkscankey(indexRel, NULL);
@@ -1188,6 +1204,7 @@ tuplesort_begin_index_btree(Relation heapRel,
    state->writetup = writetup_index;
    state->readtup = readtup_index;
    state->abbrevNext = 10;
+   state->haveDatum1 = true;
 
    state->heapRel = heapRel;
    state->indexRel = indexRel;
@@ -1262,6 +1279,7 @@ tuplesort_begin_index_hash(Relation heapRel,
    state->copytup = copytup_index;
    state->writetup = writetup_index;
    state->readtup = readtup_index;
+   state->haveDatum1 = true;
 
    state->heapRel = heapRel;
    state->indexRel = indexRel;
@@ -1302,6 +1320,7 @@ tuplesort_begin_index_gist(Relation heapRel,
    state->copytup = copytup_index;
    state->writetup = writetup_index;
    state->readtup = readtup_index;
+   state->haveDatum1 = true;
 
    state->heapRel = heapRel;
    state->indexRel = indexRel;
@@ -1366,6 +1385,7 @@ tuplesort_begin_datum(Oid datumType, Oid sortOperator, Oid sortCollation,
    state->writetup = writetup_datum;
    state->readtup = readtup_datum;
    state->abbrevNext = 10;
+   state->haveDatum1 = true;
 
    state->datumType = datumType;
 
@@ -3593,27 +3613,40 @@ tuplesort_sort_memtuples(Tuplesortstate *state)
 
    if (state->memtupcount > 1)
    {
-       /* Do we have a specialization for the leading column's comparator? */
-       if (state->sortKeys &&
-           state->sortKeys[0].comparator == ssup_datum_unsigned_cmp)
-       {
-           elog(DEBUG1, "qsort_tuple_unsigned");
-           qsort_tuple_unsigned(state->memtuples, state->memtupcount, state);
-       }
-       else if (state->sortKeys &&
-                state->sortKeys[0].comparator == ssup_datum_signed_cmp)
-       {
-           elog(DEBUG1, "qsort_tuple_signed");
-           qsort_tuple_signed(state->memtuples, state->memtupcount, state);
-       }
-       else if (state->sortKeys &&
-                state->sortKeys[0].comparator == ssup_datum_int32_cmp)
+       /*
+        * Do we have the leading column's value or abbreviation in datum1,
+        * and is there a specialization for its comparator?
+        */
+       if (state->haveDatum1 && state->sortKeys)
        {
-           elog(DEBUG1, "qsort_tuple_int32");
-           qsort_tuple_int32(state->memtuples, state->memtupcount, state);
+           if (state->sortKeys[0].comparator == ssup_datum_unsigned_cmp)
+           {
+               elog(DEBUG1, "qsort_tuple_unsigned");
+               qsort_tuple_unsigned(state->memtuples,
+                                    state->memtupcount,
+                                    state);
+               return;
+           }
+           else if (state->sortKeys[0].comparator == ssup_datum_signed_cmp)
+           {
+               elog(DEBUG1, "qsort_tuple_signed");
+               qsort_tuple_signed(state->memtuples,
+                                  state->memtupcount,
+                                  state);
+               return;
+           }
+           else if (state->sortKeys[0].comparator == ssup_datum_int32_cmp)
+           {
+               elog(DEBUG1, "qsort_tuple_int32");
+               qsort_tuple_int32(state->memtuples,
+                                 state->memtupcount,
+                                 state);
+               return;
+           }
        }
+
        /* Can we use the single-key sort function? */
-       else if (state->onlyKey != NULL)
+       if (state->onlyKey != NULL)
        {
            elog(DEBUG1, "qsort_ssup");
            qsort_ssup(state->memtuples, state->memtupcount,
@@ -4019,7 +4052,6 @@ comparetup_cluster(const SortTuple *a, const SortTuple *b,
                datum2;
    bool        isnull1,
                isnull2;
-   AttrNumber  leading = state->indexInfo->ii_IndexAttrNumbers[0];
 
    /* Be prepared to compare additional sort keys */
    ltup = (HeapTuple) a->tuple;
@@ -4027,7 +4059,7 @@ comparetup_cluster(const SortTuple *a, const SortTuple *b,
    tupDesc = state->tupDesc;
 
    /* Compare the leading sort key, if it's simple */
-   if (leading != 0)
+   if (state->haveDatum1)
    {
        compare = ApplySortComparator(a->datum1, a->isnull1,
                                      b->datum1, b->isnull1,
@@ -4037,6 +4069,8 @@ comparetup_cluster(const SortTuple *a, const SortTuple *b,
 
        if (sortKey->abbrev_converter)
        {
+           AttrNumber  leading = state->indexInfo->ii_IndexAttrNumbers[0];
+
            datum1 = heap_getattr(ltup, leading, tupDesc, &isnull1);
            datum2 = heap_getattr(rtup, leading, tupDesc, &isnull2);
 
@@ -4134,7 +4168,7 @@ copytup_cluster(Tuplesortstate *state, SortTuple *stup, void *tup)
     * set up first-column key value, and potentially abbreviate, if it's a
     * simple column
     */
-   if (state->indexInfo->ii_IndexAttrNumbers[0] == 0)
+   if (!state->haveDatum1)
        return;
 
    original = heap_getattr(tuple,
@@ -4229,7 +4263,7 @@ readtup_cluster(Tuplesortstate *state, SortTuple *stup,
        LogicalTapeReadExact(tape, &tuplen, sizeof(tuplen));
    stup->tuple = (void *) tuple;
    /* set up first-column key value, if it's a simple column */
-   if (state->indexInfo->ii_IndexAttrNumbers[0] != 0)
+   if (state->haveDatum1)
        stup->datum1 = heap_getattr(tuple,
                                    state->indexInfo->ii_IndexAttrNumbers[0],
                                    state->tupDesc,