Re: Proposal : For Auto-Prewarm.

On Tue, Jan 24, 2017 at 1:56 PM, Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com>
wrote:

> On Tue, Jan 24, 2017 at 5:07 AM, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>
> wrote:
> > I took a look at this again, and it doesn't appear to be working for me.
> The library is being loaded during startup, but I don't see any further
> activity in the log, and I don't see an autoprewarm file in $PGDATA.
>
> Hi Jim,
> 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.
>
> In my code by default, we only dump at shutdown time. If we want to
> dump at regular interval then we need to set the GUC
> pg_autoprewarm.buff_dump_interval to > 0. I think I am missing
> something while trying to recreate the bug reported above. Can you
> please let me know what exactly you mean by the library is not
> working.
>
> > There needs to be some kind of documentation change as part of this
> patch.
> Thanks, I will add a sgml for same.
>
> For remaining suggestions, I will try to address in my next patch
> based on its feasibility.
>
>
>
The patch works for me too.

Few initial comments:

1. I think the README was maintained as is from the 1st version and says
pg_autoprewarm is a contrib module. It should be rewritten to
pg_autoprewarm is a part of pg_prewarm module. The documentation should be
added to pgprewarm.sgml instead of the README

2. buff_dump_interval could be renamed to just dump_interval or
buffer_dump_interval. Also, since it is now part of pg_prewarm. I think it
makes sense to have the conf parameter be: pg_prewarm.xxx instead of
pg_autoprewarm.xxx

3. During startup we get the following message:

2017-01-24 16:13:57.615 IST [90061] LOG: Num buffers : 272

I could be better written as “pg_prewarm: 272 blocks loaded from dump” or
something similar.

4. Also, the message while dumping says:

2017-01-24 16:15:17.712 IST [90061] LOG: Buffer Dump: saved metadata of
272 blocks

It would be better to write the module name in message instead of "Buffer
Dump"

Thank you,

Beena Emerson

Have a Great Day!