Adding the ability to create a non-distributed table (can be used for postgres extensions)

src/backend/parser/gram.y

@@ -6046,6 +6046,15 @@ DistributedBy:   DISTRIBUTED BY  '(' distributed_by_list ')'
 				distributedBy->keyCols = NIL;
 				$$ = (Node *)distributedBy;
 			}
+			| DISTRIBUTED LOCAL
+			{
+				DistributedBy *distributedBy = makeNode(DistributedBy);
+				distributedBy->ptype = POLICYTYPE_LOCAL;
+				distributedBy->numsegments = -1;
+				distributedBy->keyCols = NIL;
+				$$ = (Node *)distributedBy;
+
+			}
 		;
 
 OptDistributedBy:   DistributedBy

src/backend/parser/parse_utilcmd.c

@@ -2417,6 +2417,9 @@ transformDistributedBy(ParseState *pstate,
 	ListCell   *lc;
 	int			numsegments;
 
+	if(distributedBy->ptype == POLICYTYPE_LOCAL){
+		return distributedBy;
+	}
 	/*
 	 * utility mode creates can't have a policy.  Only the QD can have policies
 	 */
@@ -3134,6 +3137,9 @@ getPolicyForDistributedBy(DistributedBy *distributedBy, TupleDesc tupdesc)
 
 		case POLICYTYPE_REPLICATED:
 			return createReplicatedGpPolicy(distributedBy->numsegments);
+
+		case POLICYTYPE_LOCAL:
+			return NULL;
 	}
 	elog(ERROR, "unrecognized policy type %d", distributedBy->ptype);
 	return NULL;

src/include/catalog/gp_distribution_policy.h

@@ -86,7 +86,8 @@ typedef enum GpPolicyType
 {
 	POLICYTYPE_PARTITIONED,		/* Tuples partitioned onto segment database. */
 	POLICYTYPE_ENTRY,			/* Tuples stored on entry database. */
-	POLICYTYPE_REPLICATED		/* Tuples stored a copy on all segment database. */
+	POLICYTYPE_REPLICATED,  	/* Tuples stored a copy on all segment database. */
+	POLICYTYPE_LOCAL            /* Tuples stored on coordinator */
 } GpPolicyType;
 
 /*

src/test/regress/expected/local_distribution.out

@@ -0,0 +1,9 @@
+-- Creates db on coordinator shard without distributing
+CREATE TABLE local_table (asd Int) DISTRIBUTED LOCAL;
+EXPLAIN SELECT * FROM local_table;
+                           QUERY PLAN                           
+----------------------------------------------------------------
+ Seq Scan on local_table  (cost=0.00..106.30 rows=9630 width=4)
+ Optimizer: Postgres query optimizer
+(2 rows)
+

src/test/regress/parallel_schedule

@@ -4,6 +4,7 @@
 # By convention, we put no more than twenty tests in any one parallel group;
 # this limits the number of connections needed to run the tests.
 # ----------
+test: local_distribution
 
 # run tablespace by itself, and first, because it forces a checkpoint;
 # we'd prefer not to have checkpoints later in the tests because that

src/test/regress/serial_schedule

@@ -1,5 +1,6 @@
 # src/test/regress/serial_schedule
 # This should probably be in an order similar to parallel_schedule.
+test: local_distribution
 test: tablespace
 test: boolean
 test: char

src/test/regress/sql/local_distribution.sql

@@ -0,0 +1,5 @@
+-- Creates db on coordinator shard without distributing
+
+CREATE TABLE local_table (asd Int) DISTRIBUTED LOCAL;
+
+EXPLAIN SELECT * FROM local_table;