From: Sergei Golubchik
Date: October 14 2010 8:44am
Subject: Re: Query Rewriting Plugin
List-Archive: http://lists.mysql.com/internals/38149
Message-Id: <20101014084400.GA13867@janus.mylan>
MIME-Version: 1.0
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Hi, Padraig!

On Oct 13, Padraig O'Sullivan wrote:
> On Wed, Oct 13, 2010 at 4:52 PM, Sergei Golubchik <serg@stripped> wrote:
> > On Oct 13, Padraig O'Sullivan wrote:
> >>
> >> I have a patch with a new plugin point for query rewriting that I'd
> >> like to have considered. It allows someone to develop a plugin
> >> which can modify the text of a query before it is parsed.
> >
> > What are the use cases?  Do you have any practical examples?
> >
> > Just to make it clear - I'm not referring to the query rewriting in
> > general, but precisely to your rewriting API, as you've implemented
> > it.
> 
> A very simple explanation of my use-case is to transform a query with
> joins into a query on virtual tables that contains no joins. I need
> this transformation to be transparent to the user who can submit their
> original queries as before.
> 
> One other possible use-case which I had thought of is to implement a
> scheme for preventing SQL injection as a query rewriting plugin.

Right. This is my point exactly.

For these applications a plugin would need a parsed tree, not the
original query string. Forcing every plugin to implement an SQL parser
would make plugins very heavyweight and writing them - prohibitevely
complex.

This didn't show up in the simple lowercase example, that's why I asked
for a real one.

See, even Peter Volk - who, by all means, is not a newbie, you could've
heard about his Revision Engine or attended his talk on UC a couple of
years ago - would prefer MySQL to do the parsing, not a plugin :)
 
> >> Any pointers to the procedure I should follow would be awesome.
> >
> > Here: http://forge.mysql.com/wiki/Contributing_Code
> 
> Cool, thanks. I sent a copy of the SCA to the email address listed on
> that page today. After I hear back from them, should I just send a
> patch to the list?

As you like. But having a tree on launchpad is good enough - they can
grab the patch from there.
 
Regards,
Sergei