1 files changed, 236 insertions, 27 deletions

diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
index 5b8d71dc267..4e1650994d5 100644
--- a/src/backend/optimizer/path/joinrels.c
+++ b/src/backend/optimizer/path/joinrels.c
@@ -45,6 +45,13 @@ static void try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1,
 static SpecialJoinInfo *build_child_join_sjinfo(PlannerInfo *root,
 												SpecialJoinInfo *parent_sjinfo,
 												Relids left_relids, Relids right_relids);
+static void compute_partition_bounds(PlannerInfo *root, RelOptInfo *rel1,
+									 RelOptInfo *rel2, RelOptInfo *joinrel,
+									 SpecialJoinInfo *parent_sjinfo,
+									 List **parts1, List **parts2);
+static void get_matching_part_pairs(PlannerInfo *root, RelOptInfo *joinrel,
+									RelOptInfo *rel1, RelOptInfo *rel2,
+									List **parts1, List **parts2);
 
 
 /*
@@ -1354,25 +1361,29 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
 {
 	bool		rel1_is_simple = IS_SIMPLE_REL(rel1);
 	bool		rel2_is_simple = IS_SIMPLE_REL(rel2);
-	int			nparts;
+	List	   *parts1 = NIL;
+	List	   *parts2 = NIL;
+	ListCell   *lcr1 = NULL;
+	ListCell   *lcr2 = NULL;
 	int			cnt_parts;
 
 	/* Guard against stack overflow due to overly deep partition hierarchy. */
 	check_stack_depth();
 
 	/* Nothing to do, if the join relation is not partitioned. */
-	if (!IS_PARTITIONED_REL(joinrel))
+	if (joinrel->part_scheme == NULL || joinrel->nparts == 0)
 		return;
 
 	/* The join relation should have consider_partitionwise_join set. */
 	Assert(joinrel->consider_partitionwise_join);
 
 	/*
-	 * Since this join relation is partitioned, all the base relations
-	 * participating in this join must be partitioned and so are all the
-	 * intermediate join relations.
+	 * We can not perform partitionwise join if either of the joining relations
+	 * is not partitioned.
 	 */
-	Assert(IS_PARTITIONED_REL(rel1) && IS_PARTITIONED_REL(rel2));
+	if (!IS_PARTITIONED_REL(rel1) || !IS_PARTITIONED_REL(rel2))
+		return;
+
 	Assert(REL_HAS_ALL_PART_PROPS(rel1) && REL_HAS_ALL_PART_PROPS(rel2));
 
 	/* The joining relations should have consider_partitionwise_join set. */
@@ -1386,35 +1397,28 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
 	Assert(joinrel->part_scheme == rel1->part_scheme &&
 		   joinrel->part_scheme == rel2->part_scheme);
 
-	/*
-	 * Since we allow partitionwise join only when the partition bounds of the
-	 * joining relations exactly match, the partition bounds of the join
-	 * should match those of the joining relations.
-	 */
-	Assert(partition_bounds_equal(joinrel->part_scheme->partnatts,
-								  joinrel->part_scheme->parttyplen,
-								  joinrel->part_scheme->parttypbyval,
-								  joinrel->boundinfo, rel1->boundinfo));
-	Assert(partition_bounds_equal(joinrel->part_scheme->partnatts,
-								  joinrel->part_scheme->parttyplen,
-								  joinrel->part_scheme->parttypbyval,
-								  joinrel->boundinfo, rel2->boundinfo));
+	Assert(!(joinrel->partbounds_merged && (joinrel->nparts <= 0)));
 
-	nparts = joinrel->nparts;
+	compute_partition_bounds(root, rel1, rel2, joinrel, parent_sjinfo,
+							 &parts1, &parts2);
+
+	if (joinrel->partbounds_merged)
+	{
+		lcr1 = list_head(parts1);
+		lcr2 = list_head(parts2);
+	}
 
 	/*
 	 * Create child-join relations for this partitioned join, if those don't
 	 * exist. Add paths to child-joins for a pair of child relations
 	 * corresponding to the given pair of parent relations.
 	 */
-	for (cnt_parts = 0; cnt_parts < nparts; cnt_parts++)
+	for (cnt_parts = 0; cnt_parts < joinrel->nparts; cnt_parts++)
 	{
-		RelOptInfo *child_rel1 = rel1->part_rels[cnt_parts];
-		RelOptInfo *child_rel2 = rel2->part_rels[cnt_parts];
-		bool		rel1_empty = (child_rel1 == NULL ||
-								  IS_DUMMY_REL(child_rel1));
-		bool		rel2_empty = (child_rel2 == NULL ||
-								  IS_DUMMY_REL(child_rel2));
+		RelOptInfo *child_rel1;
+		RelOptInfo *child_rel2;
+		bool		rel1_empty;
+		bool		rel2_empty;
 		SpecialJoinInfo *child_sjinfo;
 		List	   *child_restrictlist;
 		RelOptInfo *child_joinrel;
@@ -1422,6 +1426,22 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
 		AppendRelInfo **appinfos;
 		int			nappinfos;
 
+		if (joinrel->partbounds_merged)
+		{
+			child_rel1 = lfirst_node(RelOptInfo, lcr1);
+			child_rel2 = lfirst_node(RelOptInfo, lcr2);
+			lcr1 = lnext(parts1, lcr1);
+			lcr2 = lnext(parts2, lcr2);
+		}
+		else
+		{
+			child_rel1 = rel1->part_rels[cnt_parts];
+			child_rel2 = rel2->part_rels[cnt_parts];
+		}
+
+		rel1_empty = (child_rel1 == NULL || IS_DUMMY_REL(child_rel1));
+		rel2_empty = (child_rel2 == NULL || IS_DUMMY_REL(child_rel2));
+
 		/*
 		 * Check for cases where we can prove that this segment of the join
 		 * returns no rows, due to one or both inputs being empty (including
@@ -1519,6 +1539,8 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
 												 child_sjinfo,
 												 child_sjinfo->jointype);
 			joinrel->part_rels[cnt_parts] = child_joinrel;
+			joinrel->all_partrels = bms_add_members(joinrel->all_partrels,
+													child_joinrel->relids);
 		}
 
 		Assert(bms_equal(child_joinrel->relids, child_joinrelids));
@@ -1570,3 +1592,190 @@ build_child_join_sjinfo(PlannerInfo *root, SpecialJoinInfo *parent_sjinfo,
 
 	return sjinfo;
 }
+
+/*
+ * compute_partition_bounds
+ *		Compute the partition bounds for a join rel from those for inputs
+ */
+static void
+compute_partition_bounds(PlannerInfo *root, RelOptInfo *rel1,
+						 RelOptInfo *rel2, RelOptInfo *joinrel,
+						 SpecialJoinInfo *parent_sjinfo,
+						 List **parts1, List **parts2)
+{
+	/*
+	 * If we don't have the partition bounds for the join rel yet, try to
+	 * compute those along with pairs of partitions to be joined.
+	 */
+	if (joinrel->nparts == -1)
+	{
+		PartitionScheme part_scheme = joinrel->part_scheme;
+		PartitionBoundInfo boundinfo = NULL;
+		int			nparts = 0;
+
+		Assert(joinrel->boundinfo == NULL);
+		Assert(joinrel->part_rels == NULL);
+
+		/*
+		 * See if the partition bounds for inputs are exactly the same, in
+		 * which case we don't need to work hard: the join rel have the same
+		 * partition bounds as inputs, and the partitions with the same
+		 * cardinal positions form the pairs.
+		 *
+		 * Note: even in cases where one or both inputs have merged bounds,
+		 * it would be possible for both the bounds to be exactly the same, but
+		 * it seems unlikely to be worth the cycles to check.
+		 */
+		if (!rel1->partbounds_merged &&
+			!rel2->partbounds_merged &&
+			rel1->nparts == rel2->nparts &&
+			partition_bounds_equal(part_scheme->partnatts,
+								   part_scheme->parttyplen,
+								   part_scheme->parttypbyval,
+								   rel1->boundinfo, rel2->boundinfo))
+		{
+			boundinfo = rel1->boundinfo;
+			nparts = rel1->nparts;
+		}
+		else
+		{
+			/* Try merging the partition bounds for inputs. */
+			boundinfo = partition_bounds_merge(part_scheme->partnatts,
+											   part_scheme->partsupfunc,
+											   part_scheme->partcollation,
+											   rel1, rel2,
+											   parent_sjinfo->jointype,
+											   parts1, parts2);
+			if (boundinfo == NULL)
+			{
+				joinrel->nparts = 0;
+				return;
+			}
+			nparts = list_length(*parts1);
+			joinrel->partbounds_merged = true;
+		}
+
+		Assert(nparts > 0);
+		joinrel->boundinfo = boundinfo;
+		joinrel->nparts = nparts;
+		joinrel->part_rels =
+			(RelOptInfo **) palloc0(sizeof(RelOptInfo *) * nparts);
+	}
+	else
+	{
+		Assert(joinrel->nparts > 0);
+		Assert(joinrel->boundinfo);
+		Assert(joinrel->part_rels);
+
+		/*
+		 * If the join rel's partbounds_merged flag is true, it means inputs
+		 * are not guaranteed to have the same partition bounds, therefore we
+		 * can't assume that the partitions at the same cardinal positions form
+		 * the pairs; let get_matching_part_pairs() generate the pairs.
+		 * Otherwise, nothing to do since we can assume that.
+		 */
+		if (joinrel->partbounds_merged)
+		{
+			get_matching_part_pairs(root, joinrel, rel1, rel2,
+									parts1, parts2);
+			Assert(list_length(*parts1) == joinrel->nparts);
+			Assert(list_length(*parts2) == joinrel->nparts);
+		}
+	}
+}
+
+/*
+ * get_matching_part_pairs
+ *		Generate pairs of partitions to be joined from inputs
+ */
+static void
+get_matching_part_pairs(PlannerInfo *root, RelOptInfo *joinrel,
+						RelOptInfo *rel1, RelOptInfo *rel2,
+						List **parts1, List **parts2)
+{
+	bool		rel1_is_simple = IS_SIMPLE_REL(rel1);
+	bool		rel2_is_simple = IS_SIMPLE_REL(rel2);
+	int 		cnt_parts;
+
+	*parts1 = NIL;
+	*parts2 = NIL;
+
+	for (cnt_parts = 0; cnt_parts < joinrel->nparts; cnt_parts++)
+	{
+		RelOptInfo *child_joinrel = joinrel->part_rels[cnt_parts];
+		RelOptInfo *child_rel1;
+		RelOptInfo *child_rel2;
+		Relids		child_relids1;
+		Relids		child_relids2;
+
+		/*
+		 * If this segment of the join is empty, it means that this segment
+		 * was ignored when previously creating child-join paths for it in
+		 * try_partitionwise_join() as it would not contribute to the join
+		 * result, due to one or both inputs being empty; add NULL to each of
+		 * the given lists so that this segment will be ignored again in that
+		 * function.
+		 */
+		if (!child_joinrel)
+		{
+			*parts1 = lappend(*parts1, NULL);
+			*parts2 = lappend(*parts2, NULL);
+			continue;
+		}
+
+		/*
+		 * Get a relids set of partition(s) involved in this join segment that
+		 * are from the rel1 side.
+		 */
+		child_relids1 = bms_intersect(child_joinrel->relids,
+									  rel1->all_partrels);
+		Assert(bms_num_members(child_relids1) == bms_num_members(rel1->relids));
+
+		/*
+		 * Get a child rel for rel1 with the relids.  Note that we should have
+		 * the child rel even if rel1 is a join rel, because in that case the
+		 * partitions specified in the relids would have matching/overlapping
+		 * boundaries, so the specified partitions should be considered as ones
+		 * to be joined when planning partitionwise joins of rel1, meaning that
+		 * the child rel would have been built by the time we get here.
+		 */
+		if (rel1_is_simple)
+		{
+			int			varno = bms_singleton_member(child_relids1);
+
+			child_rel1 = find_base_rel(root, varno);
+		}
+		else
+			child_rel1 = find_join_rel(root, child_relids1);
+		Assert(child_rel1);
+
+		/*
+		 * Get a relids set of partition(s) involved in this join segment that
+		 * are from the rel2 side.
+		 */
+		child_relids2 = bms_intersect(child_joinrel->relids,
+									  rel2->all_partrels);
+		Assert(bms_num_members(child_relids2) == bms_num_members(rel2->relids));
+
+		/*
+		 * Get a child rel for rel2 with the relids.  See above comments.
+		 */
+		if (rel2_is_simple)
+		{
+			int			varno = bms_singleton_member(child_relids2);
+
+			child_rel2 = find_base_rel(root, varno);
+		}
+		else
+			child_rel2 = find_join_rel(root, child_relids2);
+		Assert(child_rel2);
+
+		/*
+		 * The join of rel1 and rel2 is legal, so is the join of the child
+		 * rels obtained above; add them to the given lists as a join pair
+		 * producing this join segment.
+		 */
+		*parts1 = lappend(*parts1, child_rel1);
+		*parts2 = lappend(*parts2, child_rel2);
+	}
+}