wait event docs

The wait event information in PostgreSQL is very helpful for
troubleshooting.  I always reference the PostgreSQL docs first, and when
people ask me about wait events that where I send them first.  The list
of wait events there is comprehensive, but the descriptions are a bit
terse and often use vocabulary that requires some familiarity with the
internals to understand.

AWS created some wait event documentation for Aurora with PostgreSQL
compatibility which takes a slightly different approach.  It's a lot
more words... but it tries to give useful suggestions about how to
improve (or fix) the system when a particular wait event is encountered.

https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraPostgreSQL.Reference.html#AuroraPostgreSQL.Reference.Waitevents

Something like this would be really valuable for open source PostgreSQL
too.  While somebody's personal blog is one solution, it doesn't seem
wholly inappropriate to live on a community resource.  I'd be happy to
seed the content and continue making updates it as I regularly helping
people solve problems on open source community PostgreSQL (and hopefully
others contribute too).

Could we create a new wiki page as a starting point, and we could draft
up and maintain something there for a little while?  Maybe a place like
https://wiki.postgresql.org/wiki/Wait_Events ?

If it does turn out to be useful for a lot of people then maybe it could
even get into the PG docs someday.  :)

-Jeremy

P.S. my wiki username is "Jer"  https://wiki.postgresql.org/wiki/User:Jer

--
Jeremy Schneider
Database Engineer
Amazon Web Services

On Thu, Dec 12, 2019 at 02:07:14PM -0800, Jeremy Schneider wrote:
> The wait event information in PostgreSQL is very helpful for
> troubleshooting.  I always reference the PostgreSQL docs first, and when
> people ask me about wait events that where I send them first.  The list
> of wait events there is comprehensive, but the descriptions are a bit
> terse and often use vocabulary that requires some familiarity with the
> internals to understand.

(I think that it would be better to avoid cross-posting among multiple
lists. Please note that I have removed -www and -general in my reply,
keeping -docs because that7s the most meaningful)

> Could we create a new wiki page as a starting point, and we could draft
> up and maintain something there for a little while?  Maybe a place like
> https://wiki.postgresql.org/wiki/Wait_Events ?

That sounds like a good idea, as it is true that the docs are rather
sparse about the meaning behind a given wait event showing a lot in
profiles and what it actually means for your application. We have a
couple of links from the docs to the wiki, so it could be an idea to
add a link to the wiki in the docs near the wait event table. more to
the point, this makes me wonder if actually a better place for such
stuff would be a new section dedicated to wait event profiles here:
/docs/devel/monitoring.html
--
Michael

On Fri, Dec 13, 2019 at 03:50:29PM +0900, Michael Paquier wrote:
> On Thu, Dec 12, 2019 at 02:07:14PM -0800, Jeremy Schneider wrote:
> > The wait event information in PostgreSQL is very helpful for
> > troubleshooting.  I always reference the PostgreSQL docs first, and when
> > people ask me about wait events that where I send them first.  The list
> > of wait events there is comprehensive, but the descriptions are a bit
> > terse and often use vocabulary that requires some familiarity with the
> > internals to understand.
>
> (I think that it would be better to avoid cross-posting among multiple
> lists. Please note that I have removed -www and -general in my reply,
> keeping -docs because that7s the most meaningful)
>
> > Could we create a new wiki page as a starting point, and we could draft
> > up and maintain something there for a little while?  Maybe a place like
> > https://wiki.postgresql.org/wiki/Wait_Events ?
>
> That sounds like a good idea, as it is true that the docs are rather
> sparse about the meaning behind a given wait event showing a lot in
> profiles and what it actually means for your application. We have a
> couple of links from the docs to the wiki, so it could be an idea to
> add a link to the wiki in the docs near the wait event table. more to
> the point, this makes me wonder if actually a better place for such
> stuff would be a new section dedicated to wait event profiles here:
> /docs/devel/monitoring.html

Agreed, it probably should be in the official docs.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +