Correct obsolete UNION hash aggs comment.

Oversight in commit 1f39bce0, which added disk-based hash aggregation.

Backpatch: 13-, where disk-based hash aggregation was introduced.

diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 951aed80e7a20df8991bb50f0a33898b971d2712..6588f83d5ec6fde6491db599b12565ac736ec8bc 100644 (file)
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -944,11 +944,10 @@ make_union_unique(SetOperationStmt *op, Path *path, List *tlist,
 
        /*
         * XXX for the moment, take the number of distinct groups as equal to the
-        * total input size, ie, the worst case.  This is too conservative, but we
-        * don't want to risk having the hashtable overrun memory; also, it's not
-        * clear how to get a decent estimate of the true size.  One should note
-        * as well the propensity of novices to write UNION rather than UNION ALL
-        * even when they don't expect any duplicates...
+        * total input size, ie, the worst case.  This is too conservative, but
+        * it's not clear how to get a decent estimate of the true size.  One
+        * should note as well the propensity of novices to write UNION rather
+        * than UNION ALL even when they don't expect any duplicates...
         */
        dNumGroups = path->rows;