How do you debug MySQL stored procedures?

Question

My current process for debugging stored procedures is very simple. I create a table called \"debug\" where I insert variable values from the stored procedure as it runs. Thi

Answer 1

MySQL user defined variable (shared in session) could be used as logging output:

DELIMITER ;;
CREATE PROCEDURE Foo(tableName VARCHAR(128))
BEGIN
  SET @stmt = CONCAT('SELECT * FROM ', tableName);
  PREPARE pStmt FROM @stmt;
  EXECUTE pStmt;
  DEALLOCATE PREPARE pStmt;
  -- uncomment after debugging to cleanup
  -- SET @stmt = null;
END;;
DELIMITER ;

call Foo('foo');
select @stmt;

will output:

SELECT * FROM foo

Answer 2

I do something very similar to you.

I'll usually include a DEBUG param that defaults to false and I can set to true at run time. Then wrap the debug statements into an "If DEBUG" block.

I also use a logging table with many of my jobs so that I can review processes and timing. My Debug code gets output there as well. I include the calling param name, a brief description, row counts affected (if appropriate), a comments field and a time stamp.

Good debugging tools is one of the sad failings of all SQL platforms.

Answer 3

How to debug a MySQL stored procedure.

Poor mans debugger:

1. Create a table called logtable with two columns, id INT and log VARCHAR(255).

2. Make the id column autoincrement.

3. Use this procedure:

   delimiter //
   DROP PROCEDURE `log_msg`//
   CREATE PROCEDURE `log_msg`(msg VARCHAR(255))
   BEGIN
       insert into logtable select 0, msg;
   END
   

4. Put this code anywhere you want to log a message to the table.

   call log_msg(concat('myvar is: ', myvar, ' and myvar2 is: ', myvar2));
   

It's a nice quick and dirty little logger to figure out what is going on.

Answer 4

Another way is presented here

http://gilfster.blogspot.co.at/2006/03/debugging-stored-procedures-in-mysql.html

with custom debug mySql procedures and logging tables.

You can also just place a simple select in your code and see if it is executed.

SELECT 'Message Text' AS `Title`; 

I got this idea from

http://forums.mysql.com/read.php?99,78155,78225#msg-78225

Also somebody created a template for custom debug procedures on GitHub.

See here

http://www.bluegecko.net/mysql/debugging-stored-procedures/ https://github.com/CaptTofu/Stored-procedure-debugging-routines

Was mentioned here

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