Re: Extension to rewrite queries before execution

Hi,

Le 13 août 2015 9:51 PM, "Jeff Janes" <jeff(dot)janes(at)gmail(dot)com> a écrit :
>
> 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.
>
> 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.
>

I know of no extension that does this, even if the idea is rather
interesting. I don't remember if there is any hook that would allow such a
thing. But that is definitely interesting.

--
Guillaume.