Re: Extension to rewrite queries before execution

On 08/13/2015 12:49 PM, Jeff Janes wrote:
> I am looking for an extension or a technique that will allow me to
> intercept a query by the exact query text, and replace that query with a
> different one.

What is sending the query?

In other words what library is the app using to communicate with the
Postgres server?

>
> The context is running a third-party app which issues queries I have no
> control over. I'd like to intercept a specific query (which has no bind
> parameters) and either replace the query text with a different text
> which, for example, swaps out an "in list" clause to instead be an
> "exists (subquery)".
>
> Or just wrap the query in a "set enable_* =off;" or "set work_mem=*;"
> before and a reset of it after.
>
> Is there anything out there like this? This would be for 9.4.
>
> I'm willing to put the query text, and its replacement, directly into
> the extension source code and compile it, but of course something more
> flexible would be ideal.
>
> Thanks,
>
> Jeff

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com