Consider disk-based hash aggregation to implement DISTINCT.
Correct oversight in If enable_hashagg_disk=true, we should
consider hash aggregation for DISTINCT when applicable.
@@ -4868,8 +4868,8 @@ create_distinct_paths(PlannerInfo *root,
Size hashentrysize = hash_agg_entry_size(
0, cheapest_input_path->pathtarget->width, 0);
- /* Allow hashing only if hashtable is predicted to fit in work_mem */
- allow_hash = (hashentrysize * numDistinctRows <= work_mem * 1024L);
+ allow_hash = enable_hashagg_disk ||
+ (hashentrysize * numDistinctRows <= work_mem * 1024L);
}
if (allow_hash && grouping_is_hashable(parse->distinctClause))
