Allow a partitioned table to have a default partition.

Any tuples that don't route to any other partition will route to the
default partition.

Jeevan Ladhe, Beena Emerson, Ashutosh Bapat, Rahila Syed, and Robert
Haas, with review and testing at various stages by (at least) Rushabh
Lathia, Keith Fiske, Amit Langote, Amul Sul, Rajkumar Raghuanshi, Sven
Kunze, Kyotaro Horiguchi, Thom Brown, Rafia Sabih, and Dilip Kumar.

Discussion: http://postgr.es/m/CAH2L28tbN4SYyhS7YV1YBWcitkqbhSWfQCy0G=apRcC_PEO-bg@mail.gmail.com
Discussion: http://postgr.es/m/CAOG9ApEYj34fWMcvBMBQ-YtqR9fTdXhdN82QEKG0SVZ6zeL1xg@mail.gmail.com

2 files changed, 32 insertions, 7 deletions

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 5eb398118e5..c303818c9b0 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -575,7 +575,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <str>			part_strategy
 %type <partelem>	part_elem
 %type <list>		part_params
-%type <partboundspec> ForValues
+%type <partboundspec> PartitionBoundSpec
 %type <node>		partbound_datum PartitionRangeDatum
 %type <list>		partbound_datum_list range_datum_list
 
@@ -1980,7 +1980,7 @@ alter_table_cmds:
 
 partition_cmd:
 			/* ALTER TABLE <name> ATTACH PARTITION <table_name> FOR VALUES */
-			ATTACH PARTITION qualified_name ForValues
+			ATTACH PARTITION qualified_name PartitionBoundSpec
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);
 					PartitionCmd *cmd = makeNode(PartitionCmd);
@@ -2635,13 +2635,14 @@ alter_identity_column_option:
 				}
 		;
 
-ForValues:
+PartitionBoundSpec:
 			/* a LIST partition */
 			FOR VALUES IN_P '(' partbound_datum_list ')'
 				{
 					PartitionBoundSpec *n = makeNode(PartitionBoundSpec);
 
 					n->strategy = PARTITION_STRATEGY_LIST;
+					n->is_default = false;
 					n->listdatums = $5;
 					n->location = @3;
 
@@ -2654,12 +2655,24 @@ ForValues:
 					PartitionBoundSpec *n = makeNode(PartitionBoundSpec);
 
 					n->strategy = PARTITION_STRATEGY_RANGE;
+					n->is_default = false;
 					n->lowerdatums = $5;
 					n->upperdatums = $9;
 					n->location = @3;
 
 					$$ = n;
 				}
+
+			/* a DEFAULT partition */
+			| DEFAULT
+				{
+					PartitionBoundSpec *n = makeNode(PartitionBoundSpec);
+
+					n->is_default = true;
+					n->location = @1;
+
+					$$ = n;
+				}
 		;
 
 partbound_datum:
@@ -3130,7 +3143,7 @@ CreateStmt:	CREATE OptTemp TABLE qualified_name '(' OptTableElementList ')'
 					$$ = (Node *)n;
 				}
 		| CREATE OptTemp TABLE qualified_name PARTITION OF qualified_name
-			OptTypedTableElementList ForValues OptPartitionSpec OptWith
+			OptTypedTableElementList PartitionBoundSpec OptPartitionSpec OptWith
 			OnCommitOption OptTableSpace
 				{
 					CreateStmt *n = makeNode(CreateStmt);
@@ -3149,7 +3162,7 @@ CreateStmt:	CREATE OptTemp TABLE qualified_name '(' OptTableElementList ')'
 					$$ = (Node *)n;
 				}
 		| CREATE OptTemp TABLE IF_P NOT EXISTS qualified_name PARTITION OF
-			qualified_name OptTypedTableElementList ForValues OptPartitionSpec
+			qualified_name OptTypedTableElementList PartitionBoundSpec OptPartitionSpec
 			OptWith OnCommitOption OptTableSpace
 				{
 					CreateStmt *n = makeNode(CreateStmt);
@@ -4864,7 +4877,7 @@ CreateForeignTableStmt:
 					$$ = (Node *) n;
 				}
 		| CREATE FOREIGN TABLE qualified_name
-			PARTITION OF qualified_name OptTypedTableElementList ForValues
+			PARTITION OF qualified_name OptTypedTableElementList PartitionBoundSpec
 			SERVER name create_generic_options
 				{
 					CreateForeignTableStmt *n = makeNode(CreateForeignTableStmt);
@@ -4885,7 +4898,7 @@ CreateForeignTableStmt:
 					$$ = (Node *) n;
 				}
 		| CREATE FOREIGN TABLE IF_P NOT EXISTS qualified_name
-			PARTITION OF qualified_name OptTypedTableElementList ForValues
+			PARTITION OF qualified_name OptTypedTableElementList PartitionBoundSpec
 			SERVER name create_generic_options
 				{
 					CreateForeignTableStmt *n = makeNode(CreateForeignTableStmt);
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 20586797cc5..655da02c109 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -3307,6 +3307,18 @@ transformPartitionBound(ParseState *pstate, Relation parent,
 	/* Avoid scribbling on input */
 	result_spec = copyObject(spec);
 
+	if (spec->is_default)
+	{
+		/*
+		 * In case of the default partition, parser had no way to identify the
+		 * partition strategy. Assign the parent's strategy to the default
+		 * partition bound spec.
+		 */
+		result_spec->strategy = strategy;
+
+		return result_spec;
+	}
+
 	if (strategy == PARTITION_STRATEGY_LIST)
 	{
 		ListCell   *cell;