diff options
Diffstat (limited to 'src/backend/executor/nodeAgg.c')
| -rw-r--r-- | src/backend/executor/nodeAgg.c | 19 |
1 files changed, 7 insertions, 12 deletions
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c index 44c159ab2a3..fbc0480fc64 100644 --- a/src/backend/executor/nodeAgg.c +++ b/src/backend/executor/nodeAgg.c @@ -1873,17 +1873,12 @@ hash_agg_update_metrics(AggState *aggstate, bool from_tape, int npartitions) aggstate->hash_disk_used = disk_used; } - /* - * Update hashentrysize estimate based on contents. Don't include meta_mem - * in the memory used, because empty buckets would inflate the per-entry - * cost. An underestimate of the per-entry size is better than an - * overestimate, because an overestimate could compound with each level of - * recursion. - */ + /* update hashentrysize estimate based on contents */ if (aggstate->hash_ngroups_current > 0) { aggstate->hashentrysize = - hash_mem / (double)aggstate->hash_ngroups_current; + sizeof(TupleHashEntryData) + + (hash_mem / (double)aggstate->hash_ngroups_current); } } @@ -1899,10 +1894,10 @@ hash_choose_num_buckets(double hashentrysize, long ngroups, Size memory) max_nbuckets = memory / hashentrysize; /* - * Leave room for slop to avoid a case where the initial hash table size - * exceeds the memory limit (though that may still happen in edge cases). + * Underestimating is better than overestimating. Too many buckets crowd + * out space for group keys and transition state values. */ - max_nbuckets *= 0.75; + max_nbuckets >>= 1; if (nbuckets > max_nbuckets) nbuckets = max_nbuckets; @@ -3548,7 +3543,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags) * reasonable. */ for (i = 0; i < aggstate->num_hashes; i++) - totalGroups = aggstate->perhash[i].aggnode->numGroups; + totalGroups += aggstate->perhash[i].aggnode->numGroups; hash_agg_set_limits(aggstate->hashentrysize, totalGroups, 0, &aggstate->hash_mem_limit, |