CREATE TABLE t1 (
id INT PRIMARY KEY,
value INT,
value2 VARCHAR(50),
INDEX(value, value2)
) ENGINE=NDB;
INSERT INTO t1 VALUES(1, 1, "val1");
# Switch to second connection
# Reset all DEBUG_SYNC points
SET DEBUG_SYNC='RESET';
# Setup ALTER TABLE to wait after GSL acquired
SET DEBUG_SYNC='ndb_global_schema_lock_acquired
                  SIGNAL got_GSL WAIT_FOR alter_continue';
# Start ALTER TABLE query, should take GSL, reach the synch
# point, signal and wait
ALTER TABLE t1 ADD COLUMN value3 BLOB DEFAULT NULL;
# Switch to default connection
# Wait for the ALTER TABLE query to signal that it has acquired the GSL
SET DEBUG_SYNC='now WAIT_FOR got_GSL';
# Start second ALTER TABLE query which will hang waiting on GSL
ALTER TABLE t1 ADD COLUMN value4 BLOB DEFAULT NULL;
# Switch to default connection
# Kill the hanging ALTER
KILL QUERY <CONNECTION_ID>;
# Switch to third connection
# Complete the killed ALTER TABLE query, it's expected to fail since
# it was killed
ERROR HY000: Lock acquisition refused by storage engine.
SHOW WARNINGS;
Level	Code	Message
Error	3177	Lock acquisition refused by storage engine.
# Tell the ALTER TABLE which holds GSL to continue processing
SET DEBUG_SYNC='now SIGNAL alter_continue';
# Switch to second connection
# Complete the ALTER TABLE query
# Switch to default connection
SET DEBUG_SYNC='RESET';
DROP TABLE t1;