Re: Query is slow when run for first time; subsequent execution is fast

On Fri, Jan 12, 2018 at 12:03 AM, Nandakumar M <m(dot)nanda92(at)gmail(dot)com> wrote:

> Hello Jeff,
>
> Thanks for the insights.
>
> >Don't keep closing and reopening connections.
>
> Even if I close a connection and open a new one and execute the same
> query, the planning time is considerably less than the first time. Only
> when I restart the Postgres server then I face high planning time again.
>

Oh. I've not seen that before. But then again I don't often restart my
server and then immediately run very large queries with a stringent time
deadline.

You can try pg_prewarm, on pg_statistic table and its index. But I'd
probably just put an entry in my db startup script to run this query
immediately after startng the server, and let the query warm the cache
itself.

Why do you restart your database often enough for this to be an issue?

Cheers,

Jeff