List *groupClause; /* overrides parse->groupClause */
} standard_qp_extra;
+/*
+ * Various flags indicating what kinds of grouping are possible.
+ *
+ * GROUPING_CAN_USE_SORT should be set if it's possible to perform
+ * sort-based implementations of grouping. When grouping sets are in use,
+ * this will be true if sorting is potentially usable for any of the grouping
+ * sets, even if it's not usable for all of them.
+ *
+ * GROUPING_CAN_USE_HASH should be set if it's possible to perform
+ * hash-based implementations of grouping.
+ *
+ * GROUPING_CAN_PARTIAL_AGG should be set if the aggregation is of a type
+ * for which we support partial aggregation (not, for example, grouping sets).
+ * It says nothing about parallel-safety or the availability of suitable paths.
+ */
+#define GROUPING_CAN_USE_SORT 0x0001
+#define GROUPING_CAN_USE_HASH 0x0002
+#define GROUPING_CAN_PARTIAL_AGG 0x0004
+
/*
* Data specific to grouping sets
*/
RelOptInfo *input_rel,
PathTarget *target, RelOptInfo *grouped_rel,
const AggClauseCosts *agg_costs,
- grouping_sets_data *gd);
+ grouping_sets_data *gd, int flags);
static void consider_groupingsets_paths(PlannerInfo *root,
RelOptInfo *grouped_rel,
Path *path,
bool can_hash,
AggClauseCosts *agg_final_costs);
static void gather_grouping_paths(PlannerInfo *root, RelOptInfo *rel);
-static bool can_parallel_agg(PlannerInfo *root, RelOptInfo *input_rel,
- RelOptInfo *grouped_rel, const AggClauseCosts *agg_costs);
+static bool can_partial_agg(PlannerInfo *root,
+ const AggClauseCosts *agg_costs);
/*****************************************************************************
if (is_degenerate_grouping(root))
create_degenerate_grouping_paths(root, input_rel, target, grouped_rel);
else
+ {
+ int flags = 0;
+
+ /*
+ * Determine whether it's possible to perform sort-based
+ * implementations of grouping. (Note that if groupClause is empty,
+ * grouping_is_sortable() is trivially true, and all the
+ * pathkeys_contained_in() tests will succeed too, so that we'll
+ * consider every surviving input path.)
+ *
+ * If we have grouping sets, we might be able to sort some but not all
+ * of them; in this case, we need can_sort to be true as long as we
+ * must consider any sorted-input plan.
+ */
+ if ((gd && gd->rollups != NIL)
+ || grouping_is_sortable(parse->groupClause))
+ flags |= GROUPING_CAN_USE_SORT;
+
+ /*
+ * Determine whether we should consider hash-based implementations of
+ * grouping.
+ *
+ * Hashed aggregation only applies if we're grouping. If we have
+ * grouping sets, some groups might be hashable but others not; in
+ * this case we set can_hash true as long as there is nothing globally
+ * preventing us from hashing (and we should therefore consider plans
+ * with hashes).
+ *
+ * Executor doesn't support hashed aggregation with DISTINCT or ORDER
+ * BY aggregates. (Doing so would imply storing *all* the input
+ * values in the hash table, and/or running many sorts in parallel,
+ * either of which seems like a certain loser.) We similarly don't
+ * support ordered-set aggregates in hashed aggregation, but that case
+ * is also included in the numOrderedAggs count.
+ *
+ * Note: grouping_is_hashable() is much more expensive to check than
+ * the other gating conditions, so we want to do it last.
+ */
+ if ((parse->groupClause != NIL &&
+ agg_costs->numOrderedAggs == 0 &&
+ (gd ? gd->any_hashable : grouping_is_hashable(parse->groupClause))))
+ flags |= GROUPING_CAN_USE_HASH;
+
+ /*
+ * Determine whether partial aggregation is possible.
+ */
+ if (can_partial_agg(root, agg_costs))
+ flags |= GROUPING_CAN_PARTIAL_AGG;
+
create_ordinary_grouping_paths(root, input_rel, target, grouped_rel,
- agg_costs, gd);
+ agg_costs, gd, flags);
+ }
set_cheapest(grouped_rel);
return grouped_rel;
create_ordinary_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
PathTarget *target, RelOptInfo *grouped_rel,
const AggClauseCosts *agg_costs,
- grouping_sets_data *gd)
+ grouping_sets_data *gd, int flags)
{
Query *parse = root->parse;
Path *cheapest_path = input_rel->cheapest_total_path;
RelOptInfo *partially_grouped_rel = NULL;
AggClauseCosts agg_final_costs; /* parallel only */
double dNumGroups;
- bool can_hash;
- bool can_sort;
+ bool can_hash = (flags & GROUPING_CAN_USE_HASH) != 0;
+ bool can_sort = (flags & GROUPING_CAN_USE_SORT) != 0;
/*
* Estimate number of groups.
gd,
parse->targetList);
- /*
- * Determine whether it's possible to perform sort-based implementations
- * of grouping. (Note that if groupClause is empty,
- * grouping_is_sortable() is trivially true, and all the
- * pathkeys_contained_in() tests will succeed too, so that we'll consider
- * every surviving input path.)
- *
- * If we have grouping sets, we might be able to sort some but not all of
- * them; in this case, we need can_sort to be true as long as we must
- * consider any sorted-input plan.
- */
- can_sort = (gd && gd->rollups != NIL)
- || grouping_is_sortable(parse->groupClause);
-
- /*
- * Determine whether we should consider hash-based implementations of
- * grouping.
- *
- * Hashed aggregation only applies if we're grouping. If we have grouping
- * sets, some groups might be hashable but others not; in this case we set
- * can_hash true as long as there is nothing globally preventing us from
- * hashing (and we should therefore consider plans with hashes).
- *
- * Executor doesn't support hashed aggregation with DISTINCT or ORDER BY
- * aggregates. (Doing so would imply storing *all* the input values in
- * the hash table, and/or running many sorts in parallel, either of which
- * seems like a certain loser.) We similarly don't support ordered-set
- * aggregates in hashed aggregation, but that case is also included in the
- * numOrderedAggs count.
- *
- * Note: grouping_is_hashable() is much more expensive to check than the
- * other gating conditions, so we want to do it last.
- */
- can_hash = (parse->groupClause != NIL &&
- agg_costs->numOrderedAggs == 0 &&
- (gd ? gd->any_hashable : grouping_is_hashable(parse->groupClause)));
-
/*
* Before generating paths for grouped_rel, we first generate any possible
* partially grouped paths; that way, later code can easily consider both
* parallel and non-parallel approaches to grouping.
*/
MemSet(&agg_final_costs, 0, sizeof(AggClauseCosts));
- if (can_parallel_agg(root, input_rel, grouped_rel, agg_costs))
+ if (grouped_rel->consider_parallel && input_rel->partial_pathlist != NIL
+ && (flags & GROUPING_CAN_PARTIAL_AGG) != 0)
{
partially_grouped_rel =
create_partial_grouping_paths(root,
}
/*
- * can_parallel_agg
+ * can_partial_agg
*
- * Determines whether or not parallel grouping and/or aggregation is possible.
+ * Determines whether or not partial grouping and/or aggregation is possible.
* Returns true when possible, false otherwise.
*/
static bool
-can_parallel_agg(PlannerInfo *root, RelOptInfo *input_rel,
- RelOptInfo *grouped_rel, const AggClauseCosts *agg_costs)
+can_partial_agg(PlannerInfo *root, const AggClauseCosts *agg_costs)
{
Query *parse = root->parse;
- if (!grouped_rel->consider_parallel)
- {
- /* Not even parallel-safe. */
- return false;
- }
- else if (input_rel->partial_pathlist == NIL)
- {
- /* Nothing to use as input for partial aggregate. */
- return false;
- }
- else if (!parse->hasAggs && parse->groupClause == NIL)
+ if (!parse->hasAggs && parse->groupClause == NIL)
{
/*
* We don't know how to do parallel aggregation unless we have either
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