Re: Publish autovacuum informations

On 04/06/2015 22:10, Guillaume Lelarge wrote:
> 2015-01-05 17:44 GMT+01:00 Guillaume Lelarge <guillaume(at)lelarge(dot)info
> <mailto:guillaume(at)lelarge(dot)info>>:
>
> 2015-01-05 17:40 GMT+01:00 Robert Haas <robertmhaas(at)gmail(dot)com
> <mailto:robertmhaas(at)gmail(dot)com>>:
>
> On Wed, Dec 31, 2014 at 12:46 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us
> <mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us>> wrote:
> > I'd be all right with putting the data structure declarations in a file
> > named something like autovacuum_private.h, especially if it carried an
> > annotation that "if you depend on this, don't be surprised if we break
> > your code in future".
>
> Works for me. I am not in general surprised when we do things that
> break my code, or anyway, the code that I'm responsible for
> maintaining. But I think it makes sense to segregate this into a
> separate header file so that we are clear that it is only
> exposed for
> the benefit of extension authors, not so that other things in
> the core
> system can touch it.
>
>
> I'm fine with that too. I'll try to find some time to work on that.
>
>
> So I took a look at this this week. I discovered, with the help of a
> coworker, that I can already use the AutoVacuumShmem pointer and read
> the struct. Unfortunately, it doesn't give me as much details as I would
> have liked. The list of databases and tables aren't in shared memory.
> They are local to the process that uses them. Putting them in shared
> memory (if at all possible) would imply a much bigger patch than I was
> willing to write right now.
>
> Thanks anyway for the help.
>
>

Sorry to revive such an old thread.

I think some hooks in the autovacuum could be enough to have good
insight without exposing private structure.

Please find attached a patch that adds some hooks to the autovacuum, and
as an example a quick proof of concept extension that use them and allow
to see what are the autovacuum worker todo list, skipped tables and so on.

I'm not really sure about which information should be provided, so I'm
open to any suggestion to improve this.
--
Julien Rouhaud
http://dalibo.com - http://dalibo.org