Error Code : 1137
Can't reopen table: 't1’

The following provides an example of this…

USE test;
 
CREATE TEMPORARY TABLE test
(
                Id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY
);
 
SELECT *
FROM test AS t1
INNER JOIN test AS t2
     ON t1.Id = t2.Id;

It’s not just self-joins that have this issue UNIONS do as well;

SELECT *
FROM test AS t1
UNION ALL
SELECT *
FROM test AS t2;

There’s a thread over on Stackoverflow discussing this problem. Here’s a solution I commonly use to get around the problem;

USE test;
 
# Create temp table
CREATE TEMPORARY TABLE test
(
                Id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY
);
 
# Insert some test data
INSERT INTO test (Id) VALUES (1),(2),(3),(4),(5);
 
# Clone the table. This will do structure & indices but no data.
CREATE TEMPORARY TABLE test2 LIKE test;
 
# Insert the data into the new table
INSERT INTO test2
SELECT Id
FROM test;
 
# Now our queries will work if we use the tables clone
SELECT *
FROM test AS t1
INNER JOIN test2 AS t2
      ON t1.Id = t2.Id;
 
SELECT *
FROM test AS t1
UNION ALL
SELECT *
FROM test2 AS t2;
 
# Clean up
DROP TEMPORARY TABLE IF EXISTS test;
DROP TEMPORARY TABLE IF EXISTS test2;

Post from: youdidwhatwithtsql.com

Can’t reopen table: ‘t1′

This procedure will allow you to easily rename MySQL Stored Procedures in any database. Please be aware that this does update the MySQL system tables and has only had minimal testing. As with all tips you find on the Internet please use with caution!

DELIMITER $$
 
USE `mysql`$$
 
DROP PROCEDURE IF EXISTS `mysp_rename_proc`$$
 
CREATE DEFINER=`root`@`%` PROCEDURE `mysp_rename_proc`(IN p_proc_name VARCHAR(64), IN p_new_name VARCHAR(64), IN p_db VARCHAR(64))
    MODIFIES SQL DATA
    SQL SECURITY INVOKER
    COMMENT 'Use to rename stored procedures.'
BEGIN
    proc: BEGIN
	# A few tests to see if the input is sensible
	IF CHARACTER_LENGTH(IFNULL(p_proc_name, '')) = 0 OR CHARACTER_LENGTH(IFNULL(p_new_name, '')) = 0
		OR CHARACTER_LENGTH(IFNULL(p_db, '')) = 0 THEN
	BEGIN
		SELECT 'Error: One of more of the input parameters is zero in length.' AS Error;
		LEAVE proc; 
	END;
	ELSEIF (SELECT COUNT(*)
		 FROM mysql.proc
		 WHERE `name` = p_proc_name
		 AND `type` = 'PROCEDURE'
		 AND db = p_db) = 0 THEN
	BEGIN
		SELECT 'Error: The procedure specified in p_proc_name does not exist in this database.' AS Error;
		LEAVE proc;
	END;
	ELSEIF (SELECT COUNT(*)
		 FROM mysql.proc
		 WHERE `name` = p_new_name
		 AND `type` = 'PROCEDURE'
		 AND db = p_db) = 1 THEN
	BEGIN
		SELECT 'Error: Unable to rename the procedure specified in p_proc_name as it already exists in this database.' AS Error;
		LEAVE proc;
	END;
	END IF;
 
	# Rename the proc
	UPDATE `mysql`.`proc`
	SET `name` = p_new_name,
	specific_name = p_new_name
	WHERE db = p_db 
	AND `name` = p_proc_name
	AND `type` = 'PROCEDURE';
 
	# Update any associated privileges
	UPDATE `mysql`.`procs_priv`
	SET Routine_name = p_new_name
	WHERE db = p_db 
	AND Routine_name = p_proc_name
	AND Routine_type = 'PROCEDURE';
 
	# Check update rowcount to see if privileges need to be flushed
	IF(SELECT ROW_COUNT()) > 0 THEN
	BEGIN
		FLUSH PRIVILEGES;
	END;
	END IF;
 
    END proc;
    END$$
 
DELIMITER ;

Usage is as follows;

CALL mysp_rename_proc('usp_proc', 'usp_new_proc_name', 'database_proc_exists_in');

As the thread poster mentions the Stored Procedure is callable by it’s old name as well as the new one until you reconnect. There doesn’t seem to be any suitable FLUSH command to resolve this.

If you liked this you may like;

MySQL Clone of SP_SpaceUsed

MySQL Clone of SP_MsForEachTable

Post from: youdidwhatwithtsql.com

Rename MySQL Stored Procedures

To safely purge binary log files, follow this procedure:

1. On each slave server, use SHOW SLAVE STATUS to check which log file it is reading.
2. Obtain a listing of the binary log files on the master server with SHOW BINARY LOGS.
3. Determine the earliest log file among all the slaves. This is the target file. If all the slaves are up to date, this is the last log file on the list.
4. Make a backup of all the log files you are about to delete. (This step is optional, but always advisable.)
5. Purge all log files up to but not including the target file. source

The below example will purge all binary logs older than the one called backup-master.001271.

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2640654
Server version: 5.1.34-log SUSE MySQL RPM

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> PURGE BINARY LOGS TO 'backup-master.001271'

Provided your slave is running this command is reasonably safe as MySQL will prevent you from purging any log files that are currently being read. If the slave thread is not running then you do have to make sure you are not purging a needed file. If you purge a needed file the slave will break when it is restarted. You can also use the expire_logs_days variable to automatically control when binary logs are purged.

Post from: youdidwhatwithtsql.com

Purge MySQL Binary Logs

Error Code : 1492
For RANGE partitions each partition must be defined

Assuming you have defined your partitions then you probably have a syntax error. Take the following incorrect example.

CREATE TABLE People
(
	PersonId INTEGER NOT NULL AUTO_INCREMENT,
	FirstName VARCHAR(50) NOT NULL,
	LastName VARCHAR(50) NOT NULL,
	DateOfBirth DATE NOT NULL,
	Telephone VARCHAR(30) NULL,
	Email VARCHAR(200) NULL,
	GroupId SMALLINT NOT NULL,
	PRIMARY KEY (PersonId, GroupId)
)
PARTITION BY RANGE (GroupId)
PARTITION p0 VALUES LESS THAN (100),
PARTITION p1 VALUES LESS THAN (200),
PARTITION p2 VALUES LESS THAN (300),
PARTITION p3 VALUES LESS THAN (400),
PARTITION p4 VALUES LESS THAN (500),
PARTITION p5 VALUES LESS THAN (600),
PARTITION p6 VALUES LESS THAN (700);

The above statement is not syntactically correct but the error thrown in this case is not particularly helpful. All that is missing here is a couple of braces around the partition range definitions. The below DDL statement is correct.

CREATE TABLE People
(
	PersonId INTEGER NOT NULL AUTO_INCREMENT,
	FirstName VARCHAR(50) NOT NULL,
	LastName VARCHAR(50) NOT NULL,
	DateOfBirth DATE NOT NULL,
	Telephone VARCHAR(30) NULL,
	Email VARCHAR(200) NULL,
	GroupId SMALLINT NOT NULL,
	PRIMARY KEY (PersonId, GroupId)
)
PARTITION BY RANGE (GroupId)
(
	PARTITION p0 VALUES LESS THAN (100),
	PARTITION p1 VALUES LESS THAN (200),
	PARTITION p2 VALUES LESS THAN (300),
	PARTITION p3 VALUES LESS THAN (400),
	PARTITION p4 VALUES LESS THAN (500),
	PARTITION p5 VALUES LESS THAN (600),
	PARTITION p6 VALUES LESS THAN (700)
);

Post from: youdidwhatwithtsql.com

For RANGE partitions each partition must be defined

Error dropping database (can't rmdir './database', errno: 39)

Then you probably have some rogue files in the folder where the database files are located. If you cd into this directory you will be able to view these files. In my case I had a tar archive containing the files the database was restored from. Just delete any files in this directory and you’ll be able to complete the drop.

Post from: youdidwhatwithtsql.com

Error dropping database (can’t rmdir ‘./database’, errno: 39)

DELIMITER $$
 
USE `db`$$
 
DROP PROCEDURE IF EXISTS `my_proc`$$
 
CREATE DEFINER=`root`@`%` PROCEDURE `my proc`()
    MODIFIES SQL DATA
    SQL SECURITY INVOKER
    COMMENT 'Just an example proc.'
BEGIN
       # // proc defintition
END$$
 
DELIMITER ;

I’ve always wondered why it did this as opposed to using the ALTER PROCEDURE Syntax.  I attempted to use this syntax but couldn’t get it to parse whatever I did. As usual the manual explains all;

This statement can be used to change the characteristics of a stored procedure. More than one change may be specified in an ALTER PROCEDURE statement. However, you cannot change the parameters or body of a stored procedure using this statement; to make such changes, you must drop and re-create the procedure using DROP PROCEDURE and CREATE PROCEDURE. source

Okay! The alter procedure statement is virtually useless to us then! The current method of dropping and then recreating routines to modify them is not atomic and can cause problems on production systems. The stored procedure is temporarily unavailable after the first drop statement so this might freak out any other thread calling it at that moment.

I admit this isn’t a massive problem, and I assume it wouldn’t be that difficult to implement, but it’s something you’d expect DBMS vendors to put in place for stored procedures. I enjoy working with MySQL but some days you can get irrated by a number of these little issues!

Post from: youdidwhatwithtsql.com

MySQL ALTER PROCEDURE Syntax

Me: “Erm… I don’t know, but it I’ll find out.”

I’ve always thought tables with these relationships should exist in the same database so I’ve never attempted this. But I don’t like not knowing things so I set to find out. The answer, as it often seems to be, is “it depends!”

Q1: Does MySQL support cross-database foreign keys?

First lets create some test databases and tables. The table called test1 will reference a table called test2 in another database.

CREATE DATABASE test1;
CREATE DATABASE test2;
 
USE test1;
 
CREATE TABLE test1
(
	idnum INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
	fk_id INT NOT NULL
) ENGINE = INNODB;
 
USE test2;
 
CREATE TABLE test2
(
	idnum INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
	fk_id INT NOT NULL,
	FOREIGN KEY fk_idnum (fk_id) REFERENCES test1.test1(idnum)
) ENGINE = INNODB;

OK, MySQL seemed to parse that without complaint. Now lets try to insert a record into table test2.

USE test2;
 
INSERT INTO test2
(
	fk_id
)
VALUES
(
	1
);

We get an error which shows the constraint is working as you would expect.

# Error Code : 1452
# Cannot add or update a child row: a foreign key constraint fails (`test2`.`test2`, CONSTRAINT `test2_ibfk_1` FOREIGN KEY (`fk_id`) REFERENCES `test1`.`test1` (`idnum`)

Insert some data into both tables now.

USE test1;
 
INSERT INTO test1
(
	fk_id
)
VALUES
(
	1
);
 
USE test2;
 
INSERT INTO test2
(
	fk_id
)
VALUES
(
	1
);
 
SELECT *
FROM test2.test2
UNION ALL
SELECT *
FROM test1.test1;

What happens if we try to drop the test1 database?

DROP DATABASE test1;

# Error Code : 1217
# Cannot delete or update a parent row: a foreign key constraint fail

To drop both the databases we need to drop them in the below sequence

# Clean up 
DROP DATABASE test2;
DROP DATABASE test1;

A1: Yes! MySQL does support cross-database foreign key references. *

* Assuming the storage engine in use supports foreign keys.

Q2: Does SQL Server support cross-database foreign keys?

CREATE DATABASE test1;
CREATE DATABASE test2;
 
USE test1;
 
CREATE TABLE test1
(
	idnum INT NOT NULL PRIMARY KEY IDENTITY(1,1),
	fk_id INT NOT NULL
);
 
USE test2;
 
CREATE TABLE test2
(
	idnum INT NOT NULL PRIMARY KEY IDENTITY(1,1),
	fk_id INT NOT NULL,
	FOREIGN KEY (fk_id) REFERENCES test1.dbo.test1(idnum)
);

Msg 1763, Level 16, State 0, Line 1
Cross-database foreign key references are not supported. Foreign key 'test1.dbo.test1'.
Msg 1750, Level 16, State 0, Line 1
Could not create constraint. See previous errors.

A2: No! SQL Server does not support cross-database foreign key references.

Chris Rock once said “You can drive a car with your feet if you want to, that don’t make it a good ******* idea!”. That’s kind of how I feel about cross-database foreign keys. Just because you can, doesn’t mean you should! I’d be inclined to have no foreign key relationship if we’re spitting up data for performance reasons. Otherwise I’d put both tables in the same database where they logically belong.

Post from: youdidwhatwithtsql.com

Cross database foreign keys?

mysql: Out of memory (Needed 4179968 bytes)
ERROR 2008 (HY000) at line 1: MySQL client ran out of memory

The fix for this is easy; just use the –quick option in your call to the mysql command. This prevents the client from caching the resultset forcing it to write each row as it is received.

mysql -q -h localhost -P 3306 -u user -psecret -D db -e 'SELECT * FROM table' > '/tmp/table.csv'

Post from: youdidwhatwithtsql.com

MySQL client ran out of memory

Save the script below to your home directory called chk_dsk_space.sh and mark this as executable. Open a terminal and enter ./chk_dsk_space.sh. You will be prompted for the password for each server before it displays disk usage information.

#!/bin/bash
 
# Set computer names here to check
computers="user@server1 user@server2 user@server3"
# Work through each computer in the array
for c in $computers
do
                echo "================================================="
                echo "= $c"
                echo "================================================="
                command="ssh $c 'df -h'"
                eval $command
done

Here’s some sample output.

rhys@linux-n0sm:~> ./chk_dsk_space.sh
=================================================
= rhys@server1
=================================================
Password:
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda6             6.7G  4.2G  2.2G  67% /
udev                  1.7G  444K  1.7G   1% /dev
/dev/sda7             8.9G  417M  8.0G   5% /home
/dev/sda2              75G   71G  4.1G  95% /windows/C
/dev/sda3              55G   47G  7.6G  86% /windows/D
=================================================
= user@server2
=================================================
Password:
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda6             6.7G  4.2G  2.2G  67% /
udev                  1.7G  444K  1.7G   1% /dev
/dev/sda7             8.9G  417M  8.0G   5% /home
/dev/sda2              75G   71G  4.1G  95% /windows/C
/dev/sda3              55G   47G  7.6G  86% /windows/D
=================================================
= user@server3
=================================================
Password:
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda6             6.7G  4.2G  2.2G  67% /
udev                  1.7G  444K  1.7G   1% /dev
/dev/sda7             8.9G  417M  8.0G   5% /home
/dev/sda2              75G   71G  4.1G  95% /windows/C
/dev/sda3              55G   47G  7.6G  86% /windows/D

Not as elegant as my Powershell script but it’s functional and saves me a little time each day. I’m not finding Bash as easy to work with as Powershell but that’s probably more due to my lack of experience than anything else. There’s an Open Source implementation of Powershell I’ve been thinking of checking out, it doesn’t implement the Windows specific cmdlets, but it’s been good to look at another way of doing things with Bash.

Post from: youdidwhatwithtsql.com

Check disk space with Bash

GRANT SHUTDOWN ON *.* TO 'multi_admin'@'localhost' IDENTIFIED BY 'secret';
FLUSH PRIVILEGES;

The mysqld_multi script needs this user, on each instance, to function correctly. This user only needs the SHUTDOWN privilege.
If you already have an instance of MySQL running then you’ll want to shut it down before beginning. You can do this at the command prompt with…

sudo /sbin/service mysql stop

Next we need to edit the my.cnf file.

First we need to comment out a few lines in the mysqld section.

# The MySQL server
[mysqld]
#port           = 3306
#socket         = /var/run/mysql/mysql.sock
# Change following line if you want to store your database elsewhere
#datadir        = /var/lib/mysql

Any other configuration options you leave in the mysqld section will serve as defaults for all MySQL instances. I’m keeping things simple here but, for production environments, you’ll want to pay more attention to these settings. I’m particulary thinking of memory usage for each instance.

# The MySQL server
[mysqld]
#port           = 3306
#socket         = /var/run/mysql/mysql.sock
# Change following line if you want to store your database elsewhere
#datadir        = /var/lib/mysql

Add the lines below replacing the username and password values the multi_admin user you created earlier. The mysqld line tells the mysqld_multi script the MySQL binary to use.

[mysqld_multi]
mysqld     = /usr/bin/mysqld_safe # location MySQL binary
mysqladmin = /usr/bin/mysqladmin
log        = /var/log/mysqld_multi.log
user       = multi_admin
password   = secret

Add the below line to create 2 instances. It is critical that each instance has its own unique values or the server will fail to start or your data could be corrupted.

[mysqld1]
port       = 3306
datadir    = /var/lib/mysql
pid-file   = /var/lib/mysql/mysqld.pid
socket     = /var/lib/mysql/mysql.sock
user       = mysql
log-error  = /var/log/mysql1.err

[mysqld2]
port       = 3307
datadir    = /var/lib/mysql-databases/mysqld2
pid-file   = /var/lib/mysql-databases/mysqld2/mysql.pid
socket     = /var/lib/mysql-databases/mysqld2/mysql.sock
user       = mysql
log-error  = /var/log/mysql2.err

Next create all the required directories on your system.

rhys@linux-n0sm:~> sudo mkdir /var/lib/mysql-databases/
rhys@linux-n0sm:~> sudo mkdir /var/lib/mysql-databases/mysqld2

Create a directory for the mysql database for instance 2.

rhys@linux-n0sm:~> sudo mkdir /var/lib/mysql-databases/mysql

Copy the mysql database files from the original instance to the second instances database directory. Then this instance will have all of the same users as instance 1.

sudo cp -r /var/lib/mysql/mysql/ /var/lib/mysql-databases/mysqld2/mysql

You can also copy across any other databases you want the new server to host. Change the owner of the data directory to the mysql user so the instance can read them.

sudo chown -R mysql:mysql /var/lib/mysql-databases

Finally we are ready to start up the instances.

rhys@linux-n0sm:~> mysqld_multi start

To check both instances have started correctly execute the below command.

rhys@linux-n0sm:~> mysqld_multi report

Reporting MySQL servers
MySQL server from group: mysqld1 is running
MySQL server from group: mysqld2 is running

You can see that the mysqld_multi script has started multiple mysql processes with the following commands.

ps -e | grep "mysql"
10779 pts/2    00:00:00 mysqld_safe
11002 pts/2    00:00:00 mysqld
11166 pts/2    00:00:00 mysqld_safe
11279 pts/2    00:00:00 mysqld

To stop both instances just execute the below command.

rhys@linux-n0sm:~> mysqld_multi stop

We are also able to control individual instances by referring to the assigned number.

rhys@linux-n0sm:~> mysqld_multi stop 1
rhys@linux-n0sm:~> mysqld_multi report
Reporting MySQL servers
MySQL server from group: mysqld1 is not running
MySQL server from group: mysqld2 is running
rhys@linux-n0sm:~> mysqld_multi start 1
rhys@linux-n0sm:~> mysqld_multi report
Reporting MySQL servers
MySQL server from group: mysqld1 is running
MySQL server from group: mysqld2 is running

Check the manual for more details on mysqld_multi.

Post from: youdidwhatwithtsql.com

Running multiple instances of MySQL