Allow partitionwise joins in more cases.

Previously, the partitionwise join technique only allowed partitionwise
join when input partitioned tables had exactly the same partition
bounds.  This commit extends the technique to some cases when the tables
have different partition bounds, by using an advanced partition-matching
algorithm introduced by this commit.  For both the input partitioned
tables, the algorithm checks whether every partition of one input
partitioned table only matches one partition of the other input
partitioned table at most, and vice versa.  In such a case the join
between the tables can be broken down into joins between the matching
partitions, so the algorithm produces the pairs of the matching
partitions, plus the partition bounds for the join relation, to allow
partitionwise join for computing the join.  Currently, the algorithm
works for list-partitioned and range-partitioned tables, but not
hash-partitioned tables.  See comments in partition_bounds_merge().

Ashutosh Bapat and Etsuro Fujita, most of regression tests by Rajkumar
Raghuwanshi, some of the tests by Mark Dilger and Amul Sul, reviewed by
Dmitry Dolgov and Amul Sul, with additional review at various points by
Ashutosh Bapat, Mark Dilger, Robert Haas, Antonin Houska, Amit Langote,
Justin Pryzby, and Tomas Vondra

Discussion: https://postgr.es/m/CAFjFpRdjQvaUEV5DJX3TW6pU5eq54NCkadtxHX2JiJG_GvbrCA@mail.gmail.com

2 files changed, 17 insertions, 1 deletions

diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index d76f88001b2..2dbd928d356 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -597,8 +597,10 @@ typedef struct PartitionSchemeData *PartitionScheme;
  *		part_scheme - Partitioning scheme of the relation
  *		nparts - Number of partitions
  *		boundinfo - Partition bounds
+ *		partbounds_merged - true if partition bounds are merged ones
  *		partition_qual - Partition constraint if not the root
  *		part_rels - RelOptInfos for each partition
+ *		all_partrels - Relids set of all partition relids
  *		partexprs, nullable_partexprs - Partition key expressions
  *		partitioned_child_rels - RT indexes of unpruned partitions of
  *								 this relation that are partitioned tables
@@ -735,11 +737,16 @@ typedef struct RelOptInfo
 
 	/* used for partitioned relations: */
 	PartitionScheme part_scheme;	/* Partitioning scheme */
-	int			nparts;			/* Number of partitions */
+	int			nparts;			/* Number of partitions; -1 if not yet set;
+								 * in case of a join relation 0 means it's
+								 * considered unpartitioned */
 	struct PartitionBoundInfoData *boundinfo;	/* Partition bounds */
+	bool		partbounds_merged;	/* True if partition bounds were created
+									 * by partition_bounds_merge() */
 	List	   *partition_qual; /* Partition constraint, if not the root */
 	struct RelOptInfo **part_rels;	/* Array of RelOptInfos of partitions,
 									 * stored in the same order as bounds */
+	Relids		all_partrels;	/* Relids set of all partition relids */
 	List	  **partexprs;		/* Non-nullable partition key expressions */
 	List	  **nullable_partexprs; /* Nullable partition key expressions */
 	List	   *partitioned_child_rels; /* List of RT indexes */
diff --git a/src/include/partitioning/partbounds.h b/src/include/partitioning/partbounds.h
index be940b51927..dfc720720b9 100644
--- a/src/include/partitioning/partbounds.h
+++ b/src/include/partitioning/partbounds.h
@@ -16,6 +16,7 @@
 #include "nodes/pg_list.h"
 #include "partitioning/partdefs.h"
 #include "utils/relcache.h"
+struct RelOptInfo;				/* avoid including pathnodes.h here */
 
 
 /*
@@ -87,6 +88,14 @@ extern bool partition_bounds_equal(int partnatts, int16 *parttyplen,
 								   PartitionBoundInfo b2);
 extern PartitionBoundInfo partition_bounds_copy(PartitionBoundInfo src,
 												PartitionKey key);
+extern PartitionBoundInfo partition_bounds_merge(int partnatts,
+												 FmgrInfo *partsupfunc,
+												 Oid *partcollation,
+												 struct RelOptInfo *outer_rel,
+												 struct RelOptInfo *inner_rel,
+												 JoinType jointype,
+												 List **outer_parts,
+												 List **inner_parts);
 extern bool partitions_are_ordered(PartitionBoundInfo boundinfo, int nparts);
 extern void check_new_partition_bound(char *relname, Relation parent,
 									  PartitionBoundSpec *spec);