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# Bug#114154 parallel read degrades to single thread read
#
# After a partition table is read in parallel for many times(at least 256),
# the parallel read will degrade to single thread read.
#
# ==== Implementation ====
# 1. Prepare the data
# 2. Do 256 (max value of --innodb_parallel_read_threads) parallel reads on
# a partitioned table while innodb_parallel_read_threads = 1.
# It used to cause parallel threads leak before the fix.
# 3. Do parallel read under innodb_parallel_read_threads = 16 and ensure that
# it does not degrade to single thread read.
# 4. cleanup
#
--source include/have_debug.inc
--echo #####################################################################
--echo # 1. Prepare
--echo #####################################################################
--echo # Create a normal table
CREATE TABLE t1(
class INT,
id INT,
title VARCHAR(100),
PRIMARY KEY(class)
) ENGINE=InnoDB;
--echo # Create a partition table
CREATE TABLE t2(
class INT,
id INT,
title VARCHAR(100),
PRIMARY KEY(class)
) ENGINE=InnoDB
PARTITION BY RANGE(class) (
PARTITION p0 VALUES LESS THAN (5000),
PARTITION p1 VALUES LESS THAN (10000),
PARTITION p2 VALUES LESS THAN (15000));
--echo # Create a procedure to insert data
DELIMITER |;
CREATE PROCEDURE populate_t1_t2()
BEGIN
DECLARE i int DEFAULT 1;
START TRANSACTION;
WHILE (i <= 1000) DO
INSERT INTO t1 VALUES (i, i, CONCAT('a', i));
INSERT INTO t2 VALUES (i, i, CONCAT('a', i));
SET i = i + 1;
END WHILE;
COMMIT;
END |
--echo # Create a procedure to repeat execute 'select count(*) from partition table'
CREATE PROCEDURE select_count_partition_table()
BEGIN
DECLARE i int DEFAULT 1;
WHILE (i <= 256) DO
SELECT COUNT(*) FROM t2;
SET i = i + 1;
END WHILE;
END |
DELIMITER ;|
--disable_result_log
--echo # Load data
CALL populate_t1_t2();
--enable_result_log
--echo #####################################################################
--echo # 2. Repeat sql 'select count(*) from t2;' for 256 times.
--echo #####################################################################
SET SESSION innodb_parallel_read_threads = 1;
--disable_result_log
CALL select_count_partition_table();
--enable_result_log
--echo #######################################################################
--echo # 3. Parallel read will degrade to single thread read before this patch
--echo #######################################################################
SET SESSION innodb_parallel_read_threads = 16;
SET GLOBAL DEBUG="+d,ib_die_if_not_parallel_read";
SELECT COUNT(*) FROM t1;
SELECT COUNT(*) FROM t2;
SET GLOBAL DEBUG="-d,ib_die_if_not_parallel_read";
--echo #####################################################################
--echo # 4. Cleanup
--echo #####################################################################
DROP PROCEDURE populate_t1_t2;
DROP PROCEDURE select_count_partition_table;
DROP TABLE t1;
DROP TABLE t2;
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