diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/nodes/bitmapset.c | 46 | ||||
| -rw-r--r-- | src/backend/optimizer/util/pathnode.c | 34 | ||||
| -rw-r--r-- | src/include/nodes/bitmapset.h | 1 | ||||
| -rw-r--r-- | src/test/regress/expected/select_parallel.out | 14 |
4 files changed, 73 insertions, 22 deletions
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c index 733fe3cf2a0..edcd19a4fd7 100644 --- a/src/backend/nodes/bitmapset.c +++ b/src/backend/nodes/bitmapset.c @@ -173,6 +173,50 @@ bms_equal(const Bitmapset *a, const Bitmapset *b) } /* + * bms_compare - qsort-style comparator for bitmapsets + * + * This guarantees to report values as equal iff bms_equal would say they are + * equal. Otherwise, the highest-numbered bit that is set in one value but + * not the other determines the result. (This rule means that, for example, + * {6} is greater than {5}, which seems plausible.) + */ +int +bms_compare(const Bitmapset *a, const Bitmapset *b) +{ + int shortlen; + int i; + + /* Handle cases where either input is NULL */ + if (a == NULL) + return bms_is_empty(b) ? 0 : -1; + else if (b == NULL) + return bms_is_empty(a) ? 0 : +1; + /* Handle cases where one input is longer than the other */ + shortlen = Min(a->nwords, b->nwords); + for (i = shortlen; i < a->nwords; i++) + { + if (a->words[i] != 0) + return +1; + } + for (i = shortlen; i < b->nwords; i++) + { + if (b->words[i] != 0) + return -1; + } + /* Process words in common */ + i = shortlen; + while (--i >= 0) + { + bitmapword aw = a->words[i]; + bitmapword bw = b->words[i]; + + if (aw != bw) + return (aw > bw) ? +1 : -1; + } + return 0; +} + +/* * bms_make_singleton - build a bitmapset containing a single member */ Bitmapset * @@ -838,7 +882,7 @@ bms_add_range(Bitmapset *a, int lower, int upper) if (lwordnum == uwordnum) { a->words[lwordnum] |= ~(bitmapword) (((bitmapword) 1 << lbitnum) - 1) - & (~(bitmapword) 0) >> ushiftbits; + & (~(bitmapword) 0) >> ushiftbits; } else { diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c index 7df87617100..48b4db72bc8 100644 --- a/src/backend/optimizer/util/pathnode.c +++ b/src/backend/optimizer/util/pathnode.c @@ -1274,38 +1274,44 @@ create_append_path(RelOptInfo *rel, /* * append_total_cost_compare - * list_qsort comparator for sorting append child paths by total_cost + * qsort comparator for sorting append child paths by total_cost descending + * + * For equal total costs, we fall back to comparing startup costs; if those + * are equal too, break ties using bms_compare on the paths' relids. + * (This is to avoid getting unpredictable results from qsort.) */ static int append_total_cost_compare(const void *a, const void *b) { Path *path1 = (Path *) lfirst(*(ListCell **) a); Path *path2 = (Path *) lfirst(*(ListCell **) b); + int cmp; - if (path1->total_cost > path2->total_cost) - return -1; - if (path1->total_cost < path2->total_cost) - return 1; - - return 0; + cmp = compare_path_costs(path1, path2, TOTAL_COST); + if (cmp != 0) + return -cmp; + return bms_compare(path1->parent->relids, path2->parent->relids); } /* * append_startup_cost_compare - * list_qsort comparator for sorting append child paths by startup_cost + * qsort comparator for sorting append child paths by startup_cost descending + * + * For equal startup costs, we fall back to comparing total costs; if those + * are equal too, break ties using bms_compare on the paths' relids. + * (This is to avoid getting unpredictable results from qsort.) */ static int append_startup_cost_compare(const void *a, const void *b) { Path *path1 = (Path *) lfirst(*(ListCell **) a); Path *path2 = (Path *) lfirst(*(ListCell **) b); + int cmp; - if (path1->startup_cost > path2->startup_cost) - return -1; - if (path1->startup_cost < path2->startup_cost) - return 1; - - return 0; + cmp = compare_path_costs(path1, path2, STARTUP_COST); + if (cmp != 0) + return -cmp; + return bms_compare(path1->parent->relids, path2->parent->relids); } /* diff --git a/src/include/nodes/bitmapset.h b/src/include/nodes/bitmapset.h index 15397e95845..67e8920f651 100644 --- a/src/include/nodes/bitmapset.h +++ b/src/include/nodes/bitmapset.h @@ -65,6 +65,7 @@ typedef enum extern Bitmapset *bms_copy(const Bitmapset *a); extern bool bms_equal(const Bitmapset *a, const Bitmapset *b); +extern int bms_compare(const Bitmapset *a, const Bitmapset *b); extern Bitmapset *bms_make_singleton(int x); extern void bms_free(Bitmapset *a); diff --git a/src/test/regress/expected/select_parallel.out b/src/test/regress/expected/select_parallel.out index 7824ca52ca4..452494fbfa3 100644 --- a/src/test/regress/expected/select_parallel.out +++ b/src/test/regress/expected/select_parallel.out @@ -21,12 +21,12 @@ explain (costs off) Workers Planned: 3 -> Partial Aggregate -> Parallel Append - -> Parallel Seq Scan on a_star - -> Parallel Seq Scan on b_star - -> Parallel Seq Scan on c_star -> Parallel Seq Scan on d_star - -> Parallel Seq Scan on e_star -> Parallel Seq Scan on f_star + -> Parallel Seq Scan on e_star + -> Parallel Seq Scan on b_star + -> Parallel Seq Scan on c_star + -> Parallel Seq Scan on a_star (11 rows) select round(avg(aa)), sum(aa) from a_star a1; @@ -49,10 +49,10 @@ explain (costs off) -> Parallel Append -> Seq Scan on d_star -> Seq Scan on c_star - -> Parallel Seq Scan on a_star - -> Parallel Seq Scan on b_star - -> Parallel Seq Scan on e_star -> Parallel Seq Scan on f_star + -> Parallel Seq Scan on e_star + -> Parallel Seq Scan on b_star + -> Parallel Seq Scan on a_star (11 rows) select round(avg(aa)), sum(aa) from a_star a2; |