path: root/mysql-test/main/ps_missed_cmds.result

SET @save_storage_engine= @@default_storage_engine;
SET default_storage_engine= InnoDB;
#
# MDEV-16708: Unsupported commands for prepared statements
#
# Disable ps-protocol explicitly in order to test support of
# prepared statements for use case when statements passed
# to the server via text client-server protocol (in contrast
# with binary protocol used in the test file
# ps_missed_cmds_bin_prot.test)
# Test case 1: Check that the statement 'LOAD DATA' is supported
# by prepared statements
# First, set up environment for use by the 'LOAD DATA' statement
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1);
COMMIT;
SELECT * INTO OUTFILE 'load.data' FROM t1;
PREPARE stmt_1 FROM "LOAD DATA INFILE 'load.data' INTO TABLE t1";
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'LOAD DATA' statement
# were damaged.
EXECUTE stmt_1;
SELECT * FROM t1;
a
1
1
1
# Clean up
DEALLOCATE PREPARE stmt_1;
DROP TABLE t1;
# Test case 2: Check that the 'LOCK TABLE', 'UNLOCK TABLES' statements
# are supported by prepared statements
CREATE TABLE t1 (a INT);
PREPARE stmt_1 FROM "LOCK TABLE t1 READ";
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'LOCK TABLE READ'
# statement were damaged.
EXECUTE stmt_1;
PREPARE stmt_1 FROM "UNLOCK TABLE";
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'UNLOCK TABLE' statement
# were damaged.
EXECUTE stmt_1;
PREPARE stmt_1 FROM "LOCK TABLE t1 WRITE";
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'LOCK TABLE WRITE'
# statement were damaged.
EXECUTE stmt_1;
# Clean up
DEALLOCATE PREPARE stmt_1;
UNLOCK TABLE;
DROP TABLE t1;
# Test case 3: Check that the 'USE' statement is supported by
# prepared statements
CREATE DATABASE mdev_16708_db;
PREPARE stmt_1 FROM 'USE mdev_16708_db';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'USE' statement
# were damaged.
EXECUTE stmt_1;
# Check that the current database has been changed
SELECT DATABASE();
DATABASE()
mdev_16708_db
# Clean up
DEALLOCATE PREPARE stmt_1;
USE test;
DROP DATABASE mdev_16708_db;
# Test case 4: Check that the 'ALTER DATABASE' statement is supported
# by prepared statements
CREATE DATABASE mdev_16708_db;
PREPARE stmt_1 FROM "ALTER DATABASE mdev_16708_db COMMENT 'New comment'";
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'ALTER DATABASE' statement
# were damaged.
EXECUTE stmt_1;
# Clean up
DEALLOCATE PREPARE stmt_1;
USE test;
DROP DATABASE mdev_16708_db;
# Test case 5: Check that the 'CREATE FUNCTION/ALTER FUNCTION/
# DROP FUNCTION' statements are supported by prepared statements
PREPARE stmt_1 FROM 'CREATE FUNCTION f1() RETURNS INT RETURN 1';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'CREATE FUNCTION'
# statement were damaged. The second attempt to execute the prepared
# statement stmt_1 results in error ER_SP_ALREADY_EXISTS since
# the stored function f() has been created on first run of stmt1.
EXECUTE stmt_1;
ERROR 42000: FUNCTION f1 already exists
PREPARE stmt_1 FROM 'ALTER FUNCTION f1 SQL SECURITY INVOKER';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'ALTER FUNCTION'
# statement were damaged.
EXECUTE stmt_1;
PREPARE stmt_1 FROM 'DROP FUNCTION f1';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling 'DROP FUNCTION' statement
# were damaged. The second attempt to run 'DROP FUNCTION f1' using
# prepared statement expectedly results in issuing the error
# ER_SP_DOES_NOT_EXIST since the stored function was dropped on first
# executuon of the prepared statement stmt_1.
EXECUTE stmt_1;
ERROR 42000: FUNCTION test.f1 does not exist
# Test case 6: Check that the 'CHECK TABLE' statement is supported
# by prepared statements
CREATE TABLE t1 (a INT);
PREPARE stmt_1 FROM 'CHECK TABLE t1';
EXECUTE stmt_1;
Table	Op	Msg_type	Msg_text
test.t1	check	status	OK
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'CHECK TABLE' statement
# were damaged.
EXECUTE stmt_1;
Table	Op	Msg_type	Msg_text
test.t1	check	status	OK
# Clean up
DEALLOCATE PREPARE stmt_1;
DROP TABLE t1;
# Test case 7: Check that the BEGIN/SAVEPOINT/RELEASE SAVEPOINT
# statements are supported by prepared statements
# Set up environmentr for the test case
CREATE TABLE t1 (a INT);
PREPARE stmt_1 FROM 'BEGIN';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'BEGIN' statement
# were damaged.
EXECUTE stmt_1;
INSERT INTO t1 VALUES (1);
# Run 'SAVEPOINT s1' using prepared statements
PREPARE stmt_2 FROM 'SAVEPOINT s1';
EXECUTE stmt_2;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'SAVEPOINT' statement
# were damaged.
EXECUTE stmt_2;
INSERT INTO t1 VALUES (2);
# Expected rows: '1' and '2'
SELECT * FROM t1;
a
1
2
# Rollback the last row inserted ('2')
ROLLBACK TO SAVEPOINT s1;
# Expected output from t1 after transaction has been rolled back
# to the savepoint is '1'. If it is case then the statement SAVEPOINT
# was handled successfully with prepared statement
SELECT * FROM t1;
a
1
PREPARE stmt_3 FROM 'RELEASE SAVEPOINT s1';
EXECUTE stmt_3;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'RELEASE' statement
# were damaged. The second attempt to release the same savepoint
# expectedly lead to error 'SAVEPOINT s1 does not exist'
# that's just ignored.
EXECUTE stmt_3;
ERROR 42000: SAVEPOINT s1 does not exist
# Clean up
DEALLOCATE PREPARE stmt_1;
DEALLOCATE PREPARE stmt_2;
DEALLOCATE PREPARE stmt_3;
DROP TABLE t1;
# Test case 8: Check that the 'PURGE BINARY LOGS BEFORE' statement
# is supported by prepared statements
PREPARE stmt_1 FROM "PURGE BINARY LOGS BEFORE '2020-11-17'";
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'PURGE BINARY LOGS BEFORE'
# statement were damaged.
EXECUTE stmt_1;
# Check that the 'PURGE BINARY LOGS TO' statement is supported by
# prepared statements
PREPARE stmt_1 FROM "PURGE BINARY LOGS TO 'mariadb-bin.000063'";
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'PURGE BINARY LOGS TO'
# statement were damaged.
EXECUTE stmt_1;
# Test case 9: Check that the 'HANDLER OPEN/HANDLER READ/
# HANDLER CLOSE' statements are supported by prepared statements
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1);
INSERT INTO t1 VALUES (1);
COMMIT;
PREPARE stmt_1 FROM 'HANDLER t1 OPEN';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'HANDLER OPEN'
# statement were damaged. Execution of this statement the second
# time expectedly results in emitting the error ER_NONUNIQ_TABLE.
# The same error is issued in case the statement 'HANDLER t1 OPEN' is
# executed twice using a regular statement.
EXECUTE stmt_1;
ERROR 42000: Not unique table/alias: 't1'
PREPARE stmt_2 FROM 'HANDLER t1 READ FIRST';
PREPARE stmt_3 FROM 'HANDLER t1 READ NEXT';
PREPARE stmt_4 FROM 'HANDLER t1 CLOSE';
EXECUTE stmt_2;
a
1
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'HANDLER READ FIRST'
# statement were damaged.
EXECUTE stmt_2;
a
1
EXECUTE stmt_3;
a
1
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'HANDLER READ NEXT'
# statement were damaged.
EXECUTE stmt_3;
a
EXECUTE stmt_4;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'HANDLER CLOSE'
# statement were damaged. Execution of this statement the second
# time results in emitting the error ER_UNKNOWN_TABLE. The same error
# is issued in case the statement 'HANDLER t1 CLOSE' executed twice
# using a regular statement.
EXECUTE stmt_4;
ERROR 42S02: Unknown table 't1' in HANDLER
# Clean up
DEALLOCATE PREPARE stmt_1;
DEALLOCATE PREPARE stmt_2;
DEALLOCATE PREPARE stmt_3;
DEALLOCATE PREPARE stmt_4;
DROP TABLE t1;
# Test case 10: Check that the HELP statement
# is supported by prepared statements
INSERT INTO mysql.help_topic VALUES (0, 'Tamagotchi', 0, 'This digital pet is not a KB article', 'no example', 'https://tamagotchi.com/');
PREPARE stmt_1 FROM "HELP `Tamagotchi`";
EXECUTE stmt_1;
name	description	example
Tamagotchi	This digital pet is not a KB article	no example
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'HELP' statement
# were damaged.
EXECUTE stmt_1;
name	description	example
Tamagotchi	This digital pet is not a KB article	no example
DELETE FROM mysql.help_topic WHERE help_topic_id = 0;
# Test case 11: Check that the 'CREATE PROCEDURE' statement
# is supported by prepared statements
PREPARE stmt_1 FROM 'CREATE PROCEDURE p1() SET @a=1';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'CREATE PROCEDURE'
# statement were damaged. Execution of this statement the second
# time expectedly results in emitting the error ER_SP_ALREADY_EXISTS.
# The same error is issued in case the 'HANDLER t1 OPEN' statement
# is executed twice using a regular statement.
EXECUTE stmt_1;
ERROR 42000: PROCEDURE p1 already exists
# Test case 12: Check that the 'ALTER PROCEDURE' statement is supported
# by prepared statements.
PREPARE stmt_1 FROM 'ALTER PROCEDURE p1 SQL SECURITY INVOKER';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'ALTER PROCEDURE'
# statement were damaged.
EXECUTE stmt_1;
# Test case 13: Check that the 'DROP PROCEDURE' statement is supported
# by prepared statements.
PREPARE stmt_1 FROM 'DROP PROCEDURE p1';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'DROP PROCEDURE' statement
# were damaged. Execution of this statement the second time expectedly
# results in emitting the error ER_SP_DOES_NOT_EXIST.
EXECUTE stmt_1;
ERROR 42000: PROCEDURE test.p1 does not exist
# Test case 14: Check that the 'CALL' statement is supported
# by prepared statements.
CREATE PROCEDURE p1() SET @a=1;
PREPARE stmt_1 FROM 'CALL p1()';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'CALL' statement
# were damaged.
EXECUTE stmt_1;
# Clean up
DEALLOCATE PREPARE stmt_1;
DROP PROCEDURE p1;
# Test case 15: Check that the 'CREATE VIEW' statement can be executed
# as a prepared statement.
# Create environment for the test case
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1);
COMMIT;
PREPARE stmt_1 FROM 'CREATE VIEW v1 AS SELECT * FROM t1';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'CREATE VIEW'
# statement were damaged. The second execution of the prepared
# statement stmt_1 results in error ER_TABLE_EXISTS_ERROR since
# the view v1 does already exist. It is expected behaviour.
EXECUTE stmt_1;
ERROR 42S01: Table 'v1' already exists
# Clean up
DEALLOCATE PREPARE stmt_1;
DROP VIEW v1;
DROP TABLE t1;
# Test case 16: Check that the 'CREATE TRIGGER' statement can be executed
# as a prepared statement.
CREATE TABLE t1 (a INT);
PREPARE stmt_1 FROM 'CREATE TRIGGER trg1 BEFORE INSERT ON t1 FOR EACH ROW SET @a=1';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'CREATE VIEW' statement
# were damaged. The second execution of the prepared statement stmt_1
# results in error ER_TRG_ALREADY_EXISTS since the trigger trg1 does
# already exist. It is expected behaviour.
EXECUTE stmt_1;
ERROR HY000: Trigger 'test.trg1' already exists
# Test case 17: Check that the 'DROP TRIGGER' statement can be executed
# as a prepared statement.
# This test relies on presence of the trigger trg1 created by
# the test case 16.
PREPARE stmt_1 FROM 'DROP TRIGGER trg1';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'DROP TRIGGER' statement
# were damaged. Execution of this statement the second time expectedly
# results in emitting the error ER_TRG_DOES_NOT_EXIST.
EXECUTE stmt_1;
ERROR HY000: Trigger does not exist
# Clean up
DEALLOCATE PREPARE stmt_1;
DROP TABLE t1;
# Test case 18: Check that XA related SQL statements can be executed
# as prepared statements.
# Create the table t1 used by XA transaction.
CREATE TABLE t1 (a INT);
PREPARE stmt_1 FROM "XA START 'xid1'";
PREPARE stmt_2 FROM "XA END 'xid1'";
PREPARE stmt_3 FROM "XA PREPARE 'xid1'";
PREPARE stmt_4 FROM "XA RECOVER";
PREPARE stmt_5 FROM "XA COMMIT 'xid1'";
PREPARE stmt_6 FROM "XA ROLLBACK 'xid1'";
# Start a new XA transaction
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'XA START' statement
# were damaged. Execution of this statement the second time expectedly
# results in emitting the error XAER_RMFAIL since there is active
# XA transaction that has just been already.
EXECUTE stmt_1;
ERROR XAE07: XAER_RMFAIL: The command cannot be executed when global transaction is in the  ACTIVE state
INSERT INTO t1 VALUES (1);
# End the current XA transaction
EXECUTE stmt_2;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'XA END' statement
# were damaged. Execution of this statement the second time expectedly
# results in emitting the error XAER_RMFAIL since the XA transaction
# with XID 'xid1' has been already ended.
EXECUTE stmt_2;
ERROR XAE07: XAER_RMFAIL: The command cannot be executed when global transaction is in the  IDLE state
# Prepare the current XA transaction for finalization
EXECUTE stmt_3;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'XA END' statement
# were damaged. Execution of this statement the second time expectedly
# results in emitting the error XAER_RMFAIL since the XA transaction
# with XID 'xid1' has been already ended.
EXECUTE stmt_3;
ERROR XAE07: XAER_RMFAIL: The command cannot be executed when global transaction is in the  PREPARED state
# Run XA RECOVER as a prepared statement
EXECUTE stmt_4;
formatID	gtrid_length	bqual_length	data
1	4	0	xid1
# And execute it yet another time to check that no internal structures
# used for handling the statement 'XA RECOVER' were damaged.
EXECUTE stmt_4;
formatID	gtrid_length	bqual_length	data
1	4	0	xid1
# Commit the current XA transaction
EXECUTE stmt_5;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'XA COMMIT' statement
# were damaged. Execution of this statement the second time expectedly
# results in emitting the error XAER_NOTA since the XA transaction
# with XID 'xid1' has been finalized and no more exists.
EXECUTE stmt_5;
ERROR XAE04: XAER_NOTA: Unknown XID
# Query the table t1 to check that it contains a record inserted by
# the XA transaction just finished.
SELECT * FROM t1;
a
1
# Using prepared statements start a new XA transaction, INSERT a row
# into the table t1, prepare the XA transaction and rollback it.
# This use case is similar to precedence one except it does rollback
# XA transaction instead commit it. Therefore every prepared statement
# is executed only once except the last XA ROLLBACK.
# Start a new XA transaction
EXECUTE stmt_1;
INSERT INTO t1 VALUES (1);
# End the current XA transaction
EXECUTE stmt_2;
# Prepare the current XA transaction for finalization
EXECUTE stmt_3;
# Rolback the current XA transaction
EXECUTE stmt_6;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the statement 'XA ROLLBACK'
# were damaged. Execution of this statement the second time expectedly
# results in emitting the error XAER_NOTA since the XA transaction
# with XID 'xid1' has been finalized and no more exists.
EXECUTE stmt_6;
ERROR XAE04: XAER_NOTA: Unknown XID
# Clean up
DROP TABLE t1;
DEALLOCATE PREPARE stmt_1;
DEALLOCATE PREPARE stmt_2;
DEALLOCATE PREPARE stmt_3;
DEALLOCATE PREPARE stmt_4;
DEALLOCATE PREPARE stmt_5;
DEALLOCATE PREPARE stmt_6;
# Test case 19: Check that the  CREATE SERVER/ALTER SERVER/DROP SERVER
# statements can be executed as prepared statements.
PREPARE stmt_1 FROM "CREATE SERVER s FOREIGN DATA WRAPPER mysql OPTIONS (USER 'u1', HOST '127.0.0.1')";
PREPARE stmt_2 FROM "ALTER SERVER s OPTIONS (USER 'u2')";
PREPARE stmt_3 FROM "DROP SERVER s";
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'CREATE SERVER' statement
# were damaged. Execution of this statement the second time expectedly
# results in emitting the error ER_FOREIGN_SERVER_EXISTS
# since a server with same has just been created.
EXECUTE stmt_1;
ERROR HY000: Cannot create foreign server 's' as it already exists
EXECUTE stmt_2;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'ALTER SERVER' statement
# were damaged.
EXECUTE stmt_2;
EXECUTE stmt_3;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'DROP SERVER' statement
# were damaged. Execution of this statement the second time expectedly
# results in emitting the error ER_FOREIGN_SERVER_DOESNT_EXIST
# since the server with same has just been dropped.
EXECUTE stmt_3;
ERROR HY000: The foreign server name you are trying to reference does not exist. Data source error:  s
# Clean up
DEALLOCATE PREPARE stmt_1;
DEALLOCATE PREPARE stmt_2;
DEALLOCATE PREPARE stmt_3;
# Test case 21: Check that the SIGNAL and RESIGNAL statements
# can be executed as a prepared statement
PREPARE stmt_1 FROM "SIGNAL SQLSTATE '45000' SET MYSQL_ERRNO=30001, MESSAGE_TEXT='Hello, world!'";
EXECUTE stmt_1;
ERROR 45000: Hello, world!
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'SIGNAL' statement
# were damaged.
EXECUTE stmt_1;
ERROR 45000: Hello, world!
PREPARE stmt_1 FROM 'RESIGNAL SET MYSQL_ERRNO = 5';
EXECUTE stmt_1;
ERROR 0K000: RESIGNAL when handler not active
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'RESIGNAL' statement
# were damaged.
EXECUTE stmt_1;
ERROR 0K000: RESIGNAL when handler not active
# Clean up
DEALLOCATE PREPARE stmt_1;
# Test case 23: Check the 'GET DIAGNOSTICS' statement
# can be executed as a prepared statement
PREPARE stmt_1 FROM 'GET DIAGNOSTICS CONDITION 1 @sqlstate = RETURNED_SQLSTATE, @errno = MYSQL_ERRNO, @text = MESSAGE_TEXT';
# Query from non existent table to fill the diagnostics area
# with information
SELECT * FROM non_existent_table_1;
ERROR 42S02: Table 'test.non_existent_table_1' doesn't exist
EXECUTE stmt_1;
# Check that information from diagnostics area has been retrieved
SELECT @sqlstate, @errno, @text;
@sqlstate	@errno	@text
42S02	1146	Table 'test.non_existent_table_1' doesn't exist
SELECT * FROM non_existent_table_1;
ERROR 42S02: Table 'test.non_existent_table_1' doesn't exist
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the
# 'GET DIAGNOSTICS CONDITION' statement were damaged.
EXECUTE stmt_1;
# Clean up
DEALLOCATE PREPARE stmt_1;
# Test case 24: Check the statements 'BACKUP'/'BACKUP UNLOCK'
# can be executed as a prepared statement
CREATE TABLE t1 (a INT);
PREPARE stmt_1 FROM 'BACKUP LOCK t1';
PREPARE stmt_2 FROM 'BACKUP UNLOCK';
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'BACKUP LOCK'
# statement were damaged.
EXECUTE stmt_1;
EXECUTE stmt_2;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'BACKUP UNLOCK'
# statement were damaged.
EXECUTE stmt_2;
# Clean up
DROP TABLE t1;
DEALLOCATE PREPARE stmt_1;
DEALLOCATE PREPARE stmt_2;
# Test Test case 25: Check the statements 'CREATE/ALTER/DROP TABLEPSPACE'
# can be executed as a prepared statement
PREPARE stmt_1 FROM "CREATE TABLESPACE ts1 ADD DATAFILE 'ts1.ibd' ENGINE=InnoDB";
PREPARE stmt_2 FROM "ALTER TABLESPACE ts1 ADD DATAFILE 'ts1_1.ibd' ENGINE=InnoDB";
PREPARE stmt_3 FROM "DROP TABLESPACE ts1 ENGINE=InnoDB";
EXECUTE stmt_1;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'CREATE TABLESPACE'
# statement were damaged.
EXECUTE stmt_1;
EXECUTE stmt_2;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'ALTER TABLESPACE'
# statement were damaged.
EXECUTE stmt_2;
EXECUTE stmt_3;
# Execute the same prepared statement the second time to check that
# no internal structures used for handling the 'DROP TABLESPACE'
# statement were damaged.
EXECUTE stmt_3;
DEALLOCATE PREPARE stmt_1;
DEALLOCATE PREPARE stmt_2;
DEALLOCATE PREPARE stmt_3;
SET default_storage_engine= @save_storage_engine;