Merge pull request #929 from citusdata/fix_create_index_if_not_exists

Avoid error during CREATE INDEX IF NOT EXISTS

cr: @jasonmp85

src/backend/distributed/executor/multi_utility.c

@@ -630,11 +630,27 @@ ProcessIndexStmt(IndexStmt *createIndexStatement, const char *createIndexCommand
 
 		if (isDistributedRelation)
 		{
+			Oid namespaceId = InvalidOid;
+			Oid indexRelationId = InvalidOid;
+			char *indexName = createIndexStatement->idxname;
+
 			ErrorIfUnsupportedIndexStmt(createIndexStatement);
 
-			/* if it is supported, go ahead and execute the command */
+			namespaceId = get_namespace_oid(namespaceName, false);
+			indexRelationId = get_relname_relid(indexName, namespaceId);
+
+			/* if index does not exist, send the command to workers */
+			if (!OidIsValid(indexRelationId))
+			{
 				ExecuteDistributedDDLCommand(relationId, createIndexCommand, isTopLevel);
 			}
+			else if (!createIndexStatement->if_not_exists)
+			{
+				/* if the index exists and there is no IF NOT EXISTS clause, error */
+				ereport(ERROR, (errcode(ERRCODE_DUPLICATE_TABLE),
+								errmsg("relation \"%s\" already exists", indexName)));
+			}
+		}
 	}
 
 	return (Node *) createIndexStatement;
@@ -807,10 +823,7 @@ ProcessAlterObjectSchemaStmt(AlterObjectSchemaStmt *alterObjectSchemaStmt,
 static void
 ErrorIfUnsupportedIndexStmt(IndexStmt *createIndexStatement)
 {
-	Oid namespaceId;
-	Oid indexRelationId;
 	char *indexRelationName = createIndexStatement->idxname;
-
 	if (indexRelationName == NULL)
 	{
 		ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -818,14 +831,6 @@ ErrorIfUnsupportedIndexStmt(IndexStmt *createIndexStatement)
 							   "currently unsupported")));
 	}
 
-	namespaceId = get_namespace_oid(createIndexStatement->relation->schemaname, false);
-	indexRelationId = get_relname_relid(indexRelationName, namespaceId);
-	if (indexRelationId != InvalidOid)
-	{
-		ereport(ERROR, (errcode(ERRCODE_DUPLICATE_TABLE),
-						errmsg("relation \"%s\" already exists", indexRelationName)));
-	}
-
 	if (createIndexStatement->tableSpace != NULL)
 	{
 		ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

src/test/regress/expected/multi_index_statements.out

@@ -80,6 +80,17 @@ CREATE UNIQUE INDEX index_test_hash_index_a_b ON index_test_hash(a,b);
 CREATE UNIQUE INDEX index_test_hash_index_a_b_partial ON index_test_hash(a,b) WHERE c IS NOT NULL;
 CREATE UNIQUE INDEX index_test_range_index_a_b_partial ON index_test_range(a,b) WHERE c IS NOT NULL;
 RESET client_min_messages;
+-- Verify that we handle if not exists statements correctly
+CREATE INDEX lineitem_orderkey_index on lineitem(l_orderkey);
+ERROR:  relation "lineitem_orderkey_index" already exists
+CREATE INDEX IF NOT EXISTS lineitem_orderkey_index on lineitem(l_orderkey);
+NOTICE:  relation "lineitem_orderkey_index" already exists, skipping
+CREATE INDEX IF NOT EXISTS lineitem_orderkey_index_new on lineitem(l_orderkey);
+-- Verify if not exists behavior with an index with same name on a different table
+CREATE INDEX lineitem_orderkey_index on index_test_hash(a);
+ERROR:  relation "lineitem_orderkey_index" already exists
+CREATE INDEX IF NOT EXISTS lineitem_orderkey_index on index_test_hash(a);
+NOTICE:  relation "lineitem_orderkey_index" already exists, skipping
 -- Verify that all indexes got created on the master node and one of the workers
 SELECT * FROM pg_indexes WHERE tablename = 'lineitem' or tablename like 'index_test_%' ORDER BY indexname;
  schemaname |    tablename     |             indexname              | tablespace |                                                      indexdef                                                       
@@ -93,17 +104,18 @@ SELECT * FROM pg_indexes WHERE tablename = 'lineitem' or tablename like 'index_t
  public     | lineitem         | lineitem_colref_index              |            | CREATE INDEX lineitem_colref_index ON lineitem USING btree (record_ne(lineitem.*, NULL::record))
  public     | lineitem         | lineitem_orderkey_hash_index       |            | CREATE INDEX lineitem_orderkey_hash_index ON lineitem USING hash (l_partkey)
  public     | lineitem         | lineitem_orderkey_index            |            | CREATE INDEX lineitem_orderkey_index ON lineitem USING btree (l_orderkey)
+ public     | lineitem         | lineitem_orderkey_index_new        |            | CREATE INDEX lineitem_orderkey_index_new ON lineitem USING btree (l_orderkey)
  public     | lineitem         | lineitem_partial_index             |            | CREATE INDEX lineitem_partial_index ON lineitem USING btree (l_shipdate) WHERE (l_shipdate < '01-01-1995'::date)
  public     | lineitem         | lineitem_partkey_desc_index        |            | CREATE INDEX lineitem_partkey_desc_index ON lineitem USING btree (l_partkey DESC)
  public     | lineitem         | lineitem_pkey                      |            | CREATE UNIQUE INDEX lineitem_pkey ON lineitem USING btree (l_orderkey, l_linenumber)
  public     | lineitem         | lineitem_time_index                |            | CREATE INDEX lineitem_time_index ON lineitem USING btree (l_shipdate)
-(13 rows)
+(14 rows)
 
 \c - - - :worker_1_port
 SELECT count(*) FROM pg_indexes WHERE tablename = (SELECT relname FROM pg_class WHERE relname LIKE 'lineitem%' ORDER BY relname LIMIT 1);
  count 
 -------
-     7
+     8
 (1 row)
 
 SELECT count(*) FROM pg_indexes WHERE tablename LIKE 'index_test_hash%';
@@ -174,11 +186,12 @@ SELECT * FROM pg_indexes WHERE tablename = 'lineitem' or tablename like 'index_t
  public     | lineitem         | lineitem_colref_index              |            | CREATE INDEX lineitem_colref_index ON lineitem USING btree (record_ne(lineitem.*, NULL::record))
  public     | lineitem         | lineitem_orderkey_hash_index       |            | CREATE INDEX lineitem_orderkey_hash_index ON lineitem USING hash (l_partkey)
  public     | lineitem         | lineitem_orderkey_index            |            | CREATE INDEX lineitem_orderkey_index ON lineitem USING btree (l_orderkey)
+ public     | lineitem         | lineitem_orderkey_index_new        |            | CREATE INDEX lineitem_orderkey_index_new ON lineitem USING btree (l_orderkey)
  public     | lineitem         | lineitem_partial_index             |            | CREATE INDEX lineitem_partial_index ON lineitem USING btree (l_shipdate) WHERE (l_shipdate < '01-01-1995'::date)
  public     | lineitem         | lineitem_partkey_desc_index        |            | CREATE INDEX lineitem_partkey_desc_index ON lineitem USING btree (l_partkey DESC)
  public     | lineitem         | lineitem_pkey                      |            | CREATE UNIQUE INDEX lineitem_pkey ON lineitem USING btree (l_orderkey, l_linenumber)
  public     | lineitem         | lineitem_time_index                |            | CREATE INDEX lineitem_time_index ON lineitem USING btree (l_shipdate)
-(13 rows)
+(14 rows)
 
 --
 -- DROP INDEX
@@ -192,6 +205,7 @@ DROP INDEX CONCURRENTLY lineitem_orderkey_index;
 ERROR:  dropping indexes concurrently on distributed tables is currently unsupported
 -- Verify that we can succesfully drop indexes
 DROP INDEX lineitem_orderkey_index;
+DROP INDEX lineitem_orderkey_index_new;
 DROP INDEX lineitem_partkey_desc_index;
 DROP INDEX lineitem_partial_index;
 DROP INDEX lineitem_colref_index;

src/test/regress/sql/multi_index_statements.sql

@@ -55,6 +55,15 @@ CREATE UNIQUE INDEX index_test_hash_index_a_b_partial ON index_test_hash(a,b) WH
 CREATE UNIQUE INDEX index_test_range_index_a_b_partial ON index_test_range(a,b) WHERE c IS NOT NULL;
 RESET client_min_messages;
 
+-- Verify that we handle if not exists statements correctly
+CREATE INDEX lineitem_orderkey_index on lineitem(l_orderkey);
+CREATE INDEX IF NOT EXISTS lineitem_orderkey_index on lineitem(l_orderkey);
+CREATE INDEX IF NOT EXISTS lineitem_orderkey_index_new on lineitem(l_orderkey);
+
+-- Verify if not exists behavior with an index with same name on a different table
+CREATE INDEX lineitem_orderkey_index on index_test_hash(a);
+CREATE INDEX IF NOT EXISTS lineitem_orderkey_index on index_test_hash(a);
+
 -- Verify that all indexes got created on the master node and one of the workers
 SELECT * FROM pg_indexes WHERE tablename = 'lineitem' or tablename like 'index_test_%' ORDER BY indexname;
 \c - - - :worker_1_port
@@ -101,6 +110,7 @@ DROP INDEX CONCURRENTLY lineitem_orderkey_index;
 
 -- Verify that we can succesfully drop indexes
 DROP INDEX lineitem_orderkey_index;
+DROP INDEX lineitem_orderkey_index_new;
 DROP INDEX lineitem_partkey_desc_index;
 DROP INDEX lineitem_partial_index;
 DROP INDEX lineitem_colref_index;