MySQL Bugs: #24720: Allow recursive stored functions

Bug #24720	Allow recursive stored functions
Submitted:	30 Nov 2006 10:25	Modified:	22 Dec 2006 12:49
Reporter:	Maciej Pilichowski	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: Stored Routines	Severity:	S4 (Feature request)
Version:	5.0.26	OS:	Linux (opensuse 10.0)
Assigned to:		CPU Architecture:	Any

Description:
I have read in a pretty decent book (about MySQL) about recurrent functions. Pretty obvious for me, so it was a bit of surprise that I am using much newer version of the MySQL than the author of the book and I cannot use recursion.

How to repeat:
Just run any function with recursion.

Suggested fix:
Please, allow functions to use recursion.

Thank you for a problem report. Please, read the manual, http://dev.mysql.com/doc/refman/5.0/en/stored-procedures.html (about max_sp_recusion_depth). This is documented behaviour.

I set it for the feature request, so I would like to see this feature implemented again -- I am not saying it is a bug ;-). Here is verbatim quote from the help you mentioned:

"recursive statements. That is, stored functions cannot be used recursively."

And this (I can just assume the book is correct) someday worked before.

Just set max_sp_recursion_depth to a recursion depth you may need (up to 255), and it will work again. See http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html for the details:

"- max_sp_recursion_depth

The number of times that a stored procedure may call itself. The default value for this option is 0, which completely disallows recursion in stored procedures. The maximum value is 255.

This variable can be set globally and per session."

Valeriy, please, FUNCTIONS not PROCEDURES. I am NOT talking about PROCEDURES you are the only person here who mention it again and again.

And I have set max_sp_recursion_depth (global) to 255 but it is NOT for functions.

So my wish is still valid -- please provide recurrent FUNCTIONS.

Yes, you are right: stored functions can not be recursive now. It is a documented limitation. Read http://dev.mysql.com/doc/refman/5.0/en/routine-restrictions.html, for example.

I think, it is a valid feature request to allow recursive functions creation again. But I am not sure when it will be implemented.