diff options
Diffstat (limited to 'src/backend/optimizer/prep/prepunion.c')
| -rw-r--r-- | src/backend/optimizer/prep/prepunion.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c index 6588f83d5ec..2ebd4ea3320 100644 --- a/src/backend/optimizer/prep/prepunion.c +++ b/src/backend/optimizer/prep/prepunion.c @@ -1018,6 +1018,7 @@ choose_hashed_setop(PlannerInfo *root, List *groupClauses, const char *construct) { int numGroupCols = list_length(groupClauses); + int hash_mem = get_hash_mem(); bool can_sort; bool can_hash; Size hashentrysize; @@ -1049,15 +1050,17 @@ choose_hashed_setop(PlannerInfo *root, List *groupClauses, /* * Don't do it if it doesn't look like the hashtable will fit into - * work_mem. + * hash_mem. */ hashentrysize = MAXALIGN(input_path->pathtarget->width) + MAXALIGN(SizeofMinimalTupleHeader); - if (hashentrysize * dNumGroups > work_mem * 1024L) + if (hashentrysize * dNumGroups > hash_mem * 1024L) return false; /* - * See if the estimated cost is no more than doing it the other way. + * See if the estimated cost is no more than doing it the other way. We + * deliberately give the hash case more memory when hash_mem exceeds + * standard work mem (i.e. when hash_mem_multiplier exceeds 1.0). * * We need to consider input_plan + hashagg versus input_plan + sort + * group. Note that the actual result plan might involve a SetOp or |