diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 171 |
1 files changed, 0 insertions, 171 deletions
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index 89031d265e..d4e8c78856 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -4364,119 +4364,6 @@ create_grouping_paths(PlannerInfo *root, } } } - - /* - * So far we've only constructed simple paths combining partial and - * distributed aggregate paths, i.e. - * - * Finalize -> RemoteSubplan -> Gather -> Partial - * - * It may however be more efficient to reduce the amount of data - * transferred over the network by generating paths like this: - * - * Finalize -> RemoteSubplan -> Combine -> Gather -> Partial - * - * where Combine deserialized the aggstates, combines them and then - * serializes them again. This AggSplit case is not defined yet, but - * should not be hard to add. - * - * We only want to do this for partial paths with RemoteSubplan on - * top of them, i.e. when the whole aggregate was not pushed down. - * - * XXX Gather output is never sorted, so we can only bother with the - * cheapest partial path here (just like above). - * - * XXX This only generates paths with both the combine and finalize - * steps using the same implementation (sort+sort or hash+hash). Maybe - * we should relax that, and allow hash+sort or sort+hash? - * - * XXX grouped_rel->partial_pathlist may be empty here, if the planner - * did not consider parallel paths (try_parallel_aggregation=false). - * But that's OK - we only want to put the combine on top of a Gather, - * so if there's none we're done. - * - * XXX The "combine" paths seem not to be picked up, most likely - * because of bad costing, not reflecting the reduction in number of - * rows transferred over the network. - */ - if (grouped_rel->partial_pathlist) - { - Path *path = (Path *) linitial(grouped_rel->partial_pathlist); - double total_groups = path->rows * path->parallel_workers; - - /* We don't care about paths that were fully pushed down. */ - if (! can_push_down_grouping(root, parse, path)) - { - path = (Path *) create_gather_path(root, - grouped_rel, - path, - partial_grouping_target, - NULL, - &total_groups); - - /* - * Gather is always unsorted, so we'll need to sort, unless - * there's no GROUP BY clause, in which case there will only be a - * single group. - */ - if (parse->groupClause) - path = (Path *) create_sort_path(root, - grouped_rel, - path, - root->group_pathkeys, - -1.0); - - /* Intermediate combine phase. */ - if (parse->hasAggs) - { - path = (Path *) create_agg_path(root, - grouped_rel, - path, - target, - parse->groupClause ? AGG_SORTED : AGG_PLAIN, - AGGSPLIT_COMBINE, - parse->groupClause, - (List *) parse->havingQual, - &agg_final_costs, - dNumGroups); - - path = create_remotesubplan_path(root, path, NULL); - - add_path(grouped_rel, (Path *) - create_agg_path(root, - grouped_rel, - path, - target, - parse->groupClause ? AGG_SORTED : AGG_PLAIN, - AGGSPLIT_FINAL_DESERIAL, - parse->groupClause, - (List *) parse->havingQual, - &agg_final_costs, - dNumGroups)); - } - else - { - path = (Path *) create_group_path(root, - grouped_rel, - path, - target, - parse->groupClause, - (List *) parse->havingQual, - dNumGroups); - - path = create_remotesubplan_path(root, path, NULL); - - add_path(grouped_rel, (Path *) - create_group_path(root, - grouped_rel, - path, - target, - parse->groupClause, - (List *) parse->havingQual, - dNumGroups)); - } - } - } } if (can_hash && try_distributed_aggregation) @@ -4557,64 +4444,6 @@ create_grouping_paths(PlannerInfo *root, } } } - - /* - * Generate a path with the extra combine phase. - * - * XXX See the comments in the block generating combine paths for - * the sorted case. - */ - if (grouped_rel->partial_pathlist) - { - Path *path = (Path *) linitial(grouped_rel->partial_pathlist); - - hashaggtablesize = estimate_hashagg_tablesize(path, - &agg_final_costs, - dNumGroups); - - /* - * Ignore the path if the hash table won't fit into memory, or - * if we managed to push dowh the whole aggregation. - */ - if ((hashaggtablesize < work_mem * 1024L) && - (! can_push_down_grouping(root, parse, path))) - { - double total_groups = path->rows * path->parallel_workers; - - path = (Path *) create_gather_path(root, - grouped_rel, - path, - partial_grouping_target, - NULL, - &total_groups); - - path = (Path *) create_agg_path(root, - grouped_rel, - path, - target, - AGG_HASHED, - AGGSPLIT_COMBINE, - parse->groupClause, - (List *) parse->havingQual, - &agg_final_costs, - dNumGroups); - - /* We know the full push down can't happen, so redistribute. */ - path = create_remotesubplan_path(root, path, NULL); - - add_path(grouped_rel, (Path *) - create_agg_path(root, - grouped_rel, - path, - target, - AGG_HASHED, - AGGSPLIT_FINAL_DESERIAL, - parse->groupClause, - (List *) parse->havingQual, - &agg_final_costs, - dNumGroups)); - } - } } /* Give a helpful error if we failed to find any implementation */ |