Comments on: Materialized Views in MySQL

By: ezani

ezani — Tue, 03 Feb 2009 07:58:36 +0000

Sorry I may have misunderstood this completely but I do not see the point of duplicating a table which already exists. Why not just use (and update or refresh) the original table ? :-o

By: Matt

Matt — Mon, 28 Aug 2006 08:58:59 +0000

Sounds like a cron job to me! :)

Cheers for the info.

By: David

David — Mon, 20 Mar 2006 14:09:14 +0000

When the select query is quite heavy isn’t it more profitable to update the view instead of re-creating it?

By: Roland Bouman

Roland Bouman — Fri, 28 Oct 2005 13:09:26 +0000

Sorry, I should’ve been more clear on that. When I said: ‘Drawback is of course that you only have the FOR EACH ROW triggers..’ I did not mean that that was a problem in your code; i just meant the general sense of ‘you’; so that it would read: ‘Drawback is of course that FOR EACH STATEMENT triggers are not supported’. My fault, sorray again.

As for frequently changing data: that’s were I think you could build an excellent solution by having each indidual change being pushed through incrementally, without reevalutating the entire set. If you post an example of your tables and your view, I’ll show you how.

Roland.

By: Marcel Oelke

Marcel Oelke — Thu, 27 Oct 2005 10:37:29 +0000

Thanks for your intresting comment Roland. I am not using the trigger in my case because the data in the tables the view builds uppon is changed very frequently. Besides i haven’t found the “AFTER STATEMENT” for triggers in the mysql documentation.

Your scheduling procedures are very intresting. maybe i’ll will use them instead of cron. thanks for that hint !

puRe

By: Roland Bouman

Roland Bouman — Thu, 27 Oct 2005 10:07:05 +0000

Hi !

nice one, glad you solved your problem.

Have you thought of writing triggers for all events that would result in an modification of the data in the MVIEW, and have those changes being incrementally pushed through immediately when the event occurs? I suspect that would be a more balanced solution especially when you have some DML going on.
Nice thing about your solution is that it’s so simple. Drawback is of course that you only have the FOR EACH ROW triggers, you’d rather use AFTER STATEMENT for this one.

BTW, you can have MySQL perform periodical procedure calls without cron or external tools, check it out:

http://rpbouman.blogspot.com/2005/10/scheduling-procedure-execution-in.html

This relies on the MySQL SLEEP() function.