Fix import foreign schema failure due to SET type.

IMPORT FOREIGN SCHEMA command fails if the schema has a table that
has a SET type column. PostgreSQL does not have an equivalent data
type to map the SET type for a successful import of the table. So,
instead of failing the entire import, skip the tables and emit
warnings for those having SET type column.

Reported on GitHub through issue #124 by Knut Wannheden.

FDW-408, Suraj Kharage with some changes by Jeevan Ladhe, some
suggestions by Jeevan Chalke, reviewed by Vaibhav Dalvi, Jeevan Ladhe
and tested by Rajkumar Raghuwanshi.

expected/select.out

@@ -1419,6 +1419,20 @@ SELECT * FROM f_test_tbl1 WHERE c1::numeric = 12.2;
    Remote query: SELECT `c1`, `c2`, `c3`, `c4`, `c5`, `c6`, `c7`, `c8` FROM `mysql_fdw_regress`.`test_tbl1` WHERE ((`c1` = 12.2))
 (3 rows)
 
+-- FDW-408: Skip importing relations that have SET type because Postgres
+-- doesn't have equivalent datatype which can be mapped to MySQL SET.
+IMPORT FOREIGN SCHEMA mysql_fdw_regress LIMIT TO (test_set, mysql_test, test_tbl1)
+  FROM SERVER mysql_svr INTO public;
+WARNING:  skipping import for relation "test_set"
+DETAIL:  MySQL SET columns are not supported.
+SELECT relname FROM pg_class
+  WHERE relname IN ('test_set', 'mysql_test', 'test_tbl1') AND relnamespace = 'public'::regnamespace;
+  relname   
+------------
+ mysql_test
+ test_tbl1
+(2 rows)
+
 -- Cleanup
 DROP TABLE l_test_tbl1;
 DROP TABLE l_test_tbl2;
@@ -1440,6 +1454,8 @@ DROP FOREIGN TABLE f_test_tbl3;
 DROP FOREIGN TABLE test5;
 DROP FOREIGN TABLE test5_1;
 DROP FOREIGN TABLE test5_2;
+DROP FOREIGN TABLE mysql_test;
+DROP FOREIGN TABLE test_tbl1;
 DROP TYPE size_t;
 DROP TYPE enum_t1_size_t;
 DROP TYPE enum_t2_size_t;

mysql_fdw.c

@@ -2228,6 +2228,7 @@ mysqlImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid)
 	{
 		char	   *tablename = row[0];
 		bool		first_item = true;
+		bool		has_set = false;
 
 		resetStringInfo(&buf);
 		appendStringInfo(&buf, "CREATE FOREIGN TABLE %s (\n",
@@ -2242,8 +2243,12 @@ mysqlImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid)
 			char	   *attnotnull;
 			char	   *attdefault;
 
-			/* If table has no columns, we'll see nulls here */
-			if (row[1] == NULL)
+			/*
+			 * If the table has no columns, we'll see nulls here. Also, if we
+			 * have already discovered this table has a SET type column, we
+			 * better skip the rest of the checking.
+			 */
+			if (row[1] == NULL || has_set)
 				continue;
 
 			attname = row[1];
@@ -2262,6 +2267,21 @@ mysqlImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid)
 						 errhint("If you encounter an error, you may need to execute the following first:\nDO $$BEGIN IF NOT EXISTS (SELECT 1 FROM pg_catalog.pg_type WHERE typname = '%s') THEN CREATE TYPE %s AS %s; END IF; END$$;\n",
 								 typename, typename, typedfn)));
 
+			/*
+			 * PostgreSQL does not have an equivalent data type to map with
+			 * SET, so skip the table definitions for the ones having SET type
+			 * column.
+			 */
+			if (strncmp(typedfn, "set", 3) == 0)
+			{
+				ereport(WARNING,
+						(errmsg("skipping import for relation \"%s\"", quote_identifier(tablename)),
+						 errdetail("MySQL SET columns are not supported.")));
+
+				has_set = true;
+				continue;
+			}
+
 			if (first_item)
 				first_item = false;
 			else
@@ -2282,6 +2302,13 @@ mysqlImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid)
 		while ((row = mysql_fetch_row(res)) &&
 			   (strcmp(row[0], tablename) == 0));
 
+		/*
+		 * As explained above, skip importing relations that have SET type
+		 * column.
+		 */
+		if (has_set)
+			continue;
+
 		/*
 		 * Add server name and table-level options.  We specify remote
 		 * database and table name as options (the latter to ensure that

mysql_init.sh

@@ -36,6 +36,7 @@ mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e
 mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e "DROP TABLE IF EXISTS test3;"
 mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e "DROP TABLE IF EXISTS test4;"
 mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e "DROP TABLE IF EXISTS test5;"
+mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e "DROP TABLE IF EXISTS test_set;"
 
 mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e "CREATE TABLE mysql_test(a int primary key, b int);"
 mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e "INSERT INTO mysql_test(a,b) VALUES (1,1);"
@@ -55,3 +56,4 @@ mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e
 mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e "CREATE TABLE test4 (c1 int PRIMARY KEY, c2 int, c3 varchar(255))"
 mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e "CREATE TABLE test5 (c1 int primary key, c2 binary, c3 binary(3), c4 binary(1), c5 binary(10), c6 varbinary(3), c7 varbinary(1), c8 varbinary(10), c9 binary(0), c10 varbinary(0));"
 mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e "INSERT INTO test5 VALUES (1, 'c', 'c3c', 't', 'c5c5c5', '04', '1', '01-10-2021', NULL, '');"
+mysql -h $MYSQL_HOST -u $MYSQL_USER_NAME -P $MYSQL_PORT -D mysql_fdw_regress -e "CREATE TABLE test_set (c1 int primary key, c2 SET('a', 'b', 'c', 'd'), c3 int);"

sql/select.sql

@@ -420,6 +420,13 @@ SELECT * FROM f_test_tbl1 WHERE c1 = 12.2;
 EXPLAIN (VERBOSE, COSTS OFF)
 SELECT * FROM f_test_tbl1 WHERE c1::numeric = 12.2;
 
+-- FDW-408: Skip importing relations that have SET type because Postgres
+-- doesn't have equivalent datatype which can be mapped to MySQL SET.
+IMPORT FOREIGN SCHEMA mysql_fdw_regress LIMIT TO (test_set, mysql_test, test_tbl1)
+  FROM SERVER mysql_svr INTO public;
+SELECT relname FROM pg_class
+  WHERE relname IN ('test_set', 'mysql_test', 'test_tbl1') AND relnamespace = 'public'::regnamespace;
+
 -- Cleanup
 DROP TABLE l_test_tbl1;
 DROP TABLE l_test_tbl2;
@@ -441,6 +448,8 @@ DROP FOREIGN TABLE f_test_tbl3;
 DROP FOREIGN TABLE test5;
 DROP FOREIGN TABLE test5_1;
 DROP FOREIGN TABLE test5_2;
+DROP FOREIGN TABLE mysql_test;
+DROP FOREIGN TABLE test_tbl1;
 DROP TYPE size_t;
 DROP TYPE enum_t1_size_t;
 DROP TYPE enum_t2_size_t;