diff options
Diffstat (limited to 'src/backend/optimizer/path/pathkeys.c')
| -rw-r--r-- | src/backend/optimizer/path/pathkeys.c | 34 |
1 files changed, 18 insertions, 16 deletions
diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c index 9775c4a7225..985b5d8de9b 100644 --- a/src/backend/optimizer/path/pathkeys.c +++ b/src/backend/optimizer/path/pathkeys.c @@ -17,6 +17,8 @@ */ #include "postgres.h" +#include <float.h> + #include "miscadmin.h" #include "access/stratnum.h" #include "catalog/pg_opfamily.h" @@ -591,7 +593,7 @@ get_cheapest_group_keys_order(PlannerInfo *root, double nrows, ListCell *cell; PathkeyMutatorState mstate; - double cheapest_sort_cost = -1.0; + double cheapest_sort_cost = DBL_MAX; int nFreeKeys; int nToPermute; @@ -620,23 +622,23 @@ get_cheapest_group_keys_order(PlannerInfo *root, double nrows, nToPermute = 4; if (nFreeKeys > nToPermute) { - int i; PathkeySortCost *costs = palloc(sizeof(PathkeySortCost) * nFreeKeys); + PathkeySortCost *cost = costs; - /* skip the pre-ordered pathkeys */ - cell = list_nth_cell(*group_pathkeys, n_preordered); - - /* estimate cost for sorting individual pathkeys */ - for (i = 0; cell != NULL; i++, (cell = lnext(*group_pathkeys, cell))) + /* + * Estimate cost for sorting individual pathkeys skipping the + * pre-ordered pathkeys. + */ + for_each_from(cell, *group_pathkeys, n_preordered) { - List *to_cost = list_make1(lfirst(cell)); - - Assert(i < nFreeKeys); + PathKey *pathkey = (PathKey *) lfirst(cell); + List *to_cost = list_make1(pathkey); - costs[i].pathkey = lfirst(cell); - costs[i].cost = cost_sort_estimate(root, to_cost, 0, nrows); + cost->pathkey = pathkey; + cost->cost = cost_sort_estimate(root, to_cost, 0, nrows); + cost++; - pfree(to_cost); + list_free(to_cost); } /* sort the pathkeys by sort cost in ascending order */ @@ -646,9 +648,9 @@ get_cheapest_group_keys_order(PlannerInfo *root, double nrows, * Rebuild the list of pathkeys - first the preordered ones, then the * rest ordered by cost. */ - new_group_pathkeys = list_truncate(list_copy(*group_pathkeys), n_preordered); + new_group_pathkeys = list_copy_head(*group_pathkeys, n_preordered); - for (i = 0; i < nFreeKeys; i++) + for (int i = 0; i < nFreeKeys; i++) new_group_pathkeys = lappend(new_group_pathkeys, costs[i].pathkey); pfree(costs); @@ -689,7 +691,7 @@ get_cheapest_group_keys_order(PlannerInfo *root, double nrows, cost = cost_sort_estimate(root, var_group_pathkeys, n_preordered, nrows); - if (cost < cheapest_sort_cost || cheapest_sort_cost < 0) + if (cost < cheapest_sort_cost) { list_free(new_group_pathkeys); new_group_pathkeys = list_copy(var_group_pathkeys); |