diff options
Diffstat (limited to 'src/backend/optimizer/path/allpaths.c')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 46 |
1 files changed, 25 insertions, 21 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index b263359fded..4db1d16c790 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -692,7 +692,7 @@ create_plain_partial_paths(PlannerInfo *root, RelOptInfo *rel) { int parallel_workers; - parallel_workers = compute_parallel_worker(rel, rel->pages, 0); + parallel_workers = compute_parallel_worker(rel, rel->pages, -1); /* If any limit was set to zero, the user doesn't want a parallel scan. */ if (parallel_workers <= 0) @@ -2938,7 +2938,7 @@ create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel, pages_fetched = compute_bitmap_pages(root, rel, bitmapqual, 1.0, NULL, NULL); - parallel_workers = compute_parallel_worker(rel, pages_fetched, 0); + parallel_workers = compute_parallel_worker(rel, pages_fetched, -1); if (parallel_workers <= 0) return; @@ -2953,16 +2953,16 @@ create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel, * 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. + * "heap_pages" is the number of pages from the table that we expect to scan, or + * -1 if we don't expect to scan any. + * + * "index_pages" is the number of pages from the index that we expect to scan, or + * -1 if we don't expect to scan any. */ int -compute_parallel_worker(RelOptInfo *rel, BlockNumber heap_pages, - BlockNumber index_pages) +compute_parallel_worker(RelOptInfo *rel, double heap_pages, double index_pages) { 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 @@ -2972,23 +2972,24 @@ compute_parallel_worker(RelOptInfo *rel, BlockNumber heap_pages, parallel_workers = rel->rel_parallel_workers; else { - int heap_parallel_threshold; - int index_parallel_threshold; - /* - * If this relation is too small to be worth a parallel scan, just - * return without doing anything ... unless it's an inheritance child. - * In that case, we want to generate a parallel path here anyway. It - * might not be worthwhile just for this relation, but when combined - * with all of its inheritance siblings it may well pay off. + * If the number of pages being scanned is insufficient to justify a + * parallel scan, just return zero ... unless it's an inheritance + * child. In that case, we want to generate a parallel path here + * anyway. It might not be worthwhile just for this relation, but + * when combined with all of its inheritance siblings it may well pay + * off. */ - if (heap_pages < (BlockNumber) min_parallel_table_scan_size && - index_pages < (BlockNumber) min_parallel_index_scan_size && - rel->reloptkind == RELOPT_BASEREL) + if (rel->reloptkind == RELOPT_BASEREL && + ((heap_pages >= 0 && heap_pages < min_parallel_table_scan_size) || + (index_pages >= 0 && index_pages < min_parallel_index_scan_size))) return 0; - if (heap_pages > 0) + if (heap_pages >= 0) { + int heap_parallel_threshold; + int heap_parallel_workers = 1; + /* * Select the number of workers based on the log of the size of * the relation. This probably needs to be a good deal more @@ -3008,8 +3009,11 @@ compute_parallel_worker(RelOptInfo *rel, BlockNumber heap_pages, parallel_workers = heap_parallel_workers; } - if (index_pages > 0) + if (index_pages >= 0) { + int index_parallel_workers = 1; + int index_parallel_threshold; + /* 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)) |