diff options
Diffstat (limited to 'src/backend/optimizer/path/allpaths.c')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 79 |
1 files changed, 56 insertions, 23 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index 5c189874efa..85505c57d36 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -57,7 +57,8 @@ typedef struct pushdown_safety_info /* These parameters are set by GUC */ bool enable_geqo = false; /* just in case GUC doesn't set it */ int geqo_threshold; -int min_parallel_relation_size; +int min_parallel_table_scan_size; +int min_parallel_index_scan_size; /* Hook for plugins to get control in set_rel_pathlist() */ set_rel_pathlist_hook_type set_rel_pathlist_hook = NULL; @@ -126,7 +127,8 @@ static void subquery_push_qual(Query *subquery, static void recurse_push_qual(Node *setOp, Query *topquery, RangeTblEntry *rte, Index rti, Node *qual); static void remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel); -static int compute_parallel_worker(RelOptInfo *rel, BlockNumber pages); +static int compute_parallel_worker(RelOptInfo *rel, BlockNumber heap_pages, + BlockNumber index_pages); /* @@ -679,7 +681,7 @@ create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel) { int parallel_workers; - parallel_workers = compute_parallel_worker(rel, rel->pages); + parallel_workers = compute_parallel_worker(rel, rel->pages, 0); /* If any limit was set to zero, the user doesn't want a parallel scan. */ if (parallel_workers <= 0) @@ -2876,13 +2878,20 @@ remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel) /* * Compute the number of parallel workers that should be used to scan a - * relation. "pages" is the number of pages from the relation that we - * expect to scan. + * relation. We compute the parallel workers based on the size of the heap to + * be scanned and the size of the index to be scanned, then choose a minimum + * of those. + * + * "heap_pages" is the number of pages from the table that we expect to scan. + * "index_pages" is the number of pages from the index that we expect to scan. */ static int -compute_parallel_worker(RelOptInfo *rel, BlockNumber pages) +compute_parallel_worker(RelOptInfo *rel, BlockNumber heap_pages, + BlockNumber index_pages) { - int parallel_workers; + int parallel_workers = 0; + int heap_parallel_workers = 1; + int index_parallel_workers = 1; /* * If the user has set the parallel_workers reloption, use that; otherwise @@ -2892,7 +2901,8 @@ compute_parallel_worker(RelOptInfo *rel, BlockNumber pages) parallel_workers = rel->rel_parallel_workers; else { - int parallel_threshold; + int heap_parallel_threshold; + int index_parallel_threshold; /* * If this relation is too small to be worth a parallel scan, just @@ -2901,25 +2911,48 @@ compute_parallel_worker(RelOptInfo *rel, BlockNumber pages) * might not be worthwhile just for this relation, but when combined * with all of its inheritance siblings it may well pay off. */ - if (pages < (BlockNumber) min_parallel_relation_size && + if (heap_pages < (BlockNumber) min_parallel_table_scan_size && + index_pages < (BlockNumber) min_parallel_index_scan_size && rel->reloptkind == RELOPT_BASEREL) return 0; - /* - * Select the number of workers based on the log of the size of the - * relation. This probably needs to be a good deal more - * sophisticated, but we need something here for now. Note that the - * upper limit of the min_parallel_relation_size GUC is chosen to - * prevent overflow here. - */ - parallel_workers = 1; - parallel_threshold = Max(min_parallel_relation_size, 1); - while (pages >= (BlockNumber) (parallel_threshold * 3)) + if (heap_pages > 0) + { + /* + * Select the number of workers based on the log of the size of + * the relation. This probably needs to be a good deal more + * sophisticated, but we need something here for now. Note that + * the upper limit of the min_parallel_table_scan_size GUC is + * chosen to prevent overflow here. + */ + heap_parallel_threshold = Max(min_parallel_table_scan_size, 1); + while (heap_pages >= (BlockNumber) (heap_parallel_threshold * 3)) + { + heap_parallel_workers++; + heap_parallel_threshold *= 3; + if (heap_parallel_threshold > INT_MAX / 3) + break; /* avoid overflow */ + } + + parallel_workers = heap_parallel_workers; + } + + if (index_pages > 0) { - parallel_workers++; - parallel_threshold *= 3; - if (parallel_threshold > INT_MAX / 3) - break; /* avoid overflow */ + /* same calculation as for heap_pages above */ + index_parallel_threshold = Max(min_parallel_index_scan_size, 1); + while (index_pages >= (BlockNumber) (index_parallel_threshold * 3)) + { + index_parallel_workers++; + index_parallel_threshold *= 3; + if (index_parallel_threshold > INT_MAX / 3) + break; /* avoid overflow */ + } + + if (parallel_workers > 0) + parallel_workers = Min(parallel_workers, index_parallel_workers); + else + parallel_workers = index_parallel_workers; } } |