Re: [HACKERS] Proposal : For Auto-Prewarm.

On 1/24/17 11:13 PM, Beena Emerson wrote:
>
> On Wed, Jan 25, 2017 at 10:36 AM, Jim Nasby <Jim.Nasby@bluetreble.com
> <mailto:Jim.Nasby@bluetreble.com>> wrote:
>
>     On 1/24/17 2:26 AM, Mithun Cy wrote:
>
>         Thanks for looking into this patch, I just downloaded the patch and
>         applied same to the latest code, I can see file "
>         autoprewarm.save" in
>         $PGDATA which is created and dumped at shutdown time and an activity
>         is logged as below
>         2017-01-24 13:22:25.012 IST [91755] LOG:  Buffer Dump: saved
>         metadata
>         of 59 blocks.
>
>
>     Yeah, I wasn't getting that at all, though I did see the shared
>     library being loaded. If I get a chance I'll try it again.
>
>
>
> Hope u added the following to the conf file:
>
> shared_preload_libraries = 'pg_autoprewarm'     # (change requires restart)

Therein lied my problem: I was preloading pg_prewarm, not pg_autoprewarm.

I think the two need to be integrated much better than they are right 
now. They should certainly be in the same .so, and as others have 
mentioned the docs need to be fixed. For consistency, I think the name 
should just be pg_prewarm, as well as the prefix for the GUC.

Based on that and other feedback I'm going to mark this as returned with 
feedback, though if you're able to get a revised patch in the next few 
days please do.

FYI (and this is just a suggestion), for testing purposes, it might also 
be handy to allow manual dump and load via functions, with the load 
function giving you the option to forcibly load (instead of doing 
nothing if there are no buffers on the free list). It would also be 
handy of those functions accepted a different filename. That way you 
could reset shared_buffers to a known condition before running a test.
-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
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