Is autovacuum doing a wraparound-avoiding VACUUM?

Simon Riggs wrote:

Is autovacuum doing a wraparound-avoiding VACUUM?
Currently, no easy way to tell.

Patch to change message of autovac in pg_stat_activity when we are
performing an anti-wraparound VACUUM.

I just obsoleted this patch. The new patch should be easier to do
though -- just a one line change I think.

I don't like your wording though; it feels too verbose (and you're
losing the ANALYZE in case it's doing both things). How about

snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
"autovacuum: VACUUM%s%s", vac
tab->at_doanalyze ? " ANALYZE" : "",
tab->at_wraparound ? " (wraparound)" : "");

You're not proposing it for 8.3 right?

--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

On Thu, 2008-07-17 at 17:10 -0400, Alvaro Herrera wrote:

Simon Riggs wrote:

Is autovacuum doing a wraparound-avoiding VACUUM?
Currently, no easy way to tell.

Patch to change message of autovac in pg_stat_activity when we are
performing an anti-wraparound VACUUM.

I just obsoleted this patch. The new patch should be easier to do
though -- just a one line change I think.

I don't like your wording though; it feels too verbose (and you're
losing the ANALYZE in case it's doing both things). How about

snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
"autovacuum: VACUUM%s%s", vac
tab->at_doanalyze ? " ANALYZE" : "",
tab->at_wraparound ? " (wraparound)" : "");

Yes, looks good.

Losing the ANALYZE was conscious, but in retrospect is something we
might live to regret. Yours is better.

You're not proposing it for 8.3 right?

I think I am. It's an important diagnostic for your other fix.

We need to be able to tell the difference between a wraparound and other
weird situations.

--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support

Simon Riggs <simon@2ndquadrant.com> writes:

On Thu, 2008-07-17 at 17:10 -0400, Alvaro Herrera wrote:

I don't like your wording though; it feels too verbose (and you're
losing the ANALYZE in case it's doing both things). How about

snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
"autovacuum: VACUUM%s%s", vac
tab->at_doanalyze ? " ANALYZE" : "",
tab->at_wraparound ? " (wraparound)" : "");

Yes, looks good.

May I suggest "(to prevent wraparound)" or something like that?
Otherwise, +1.

You're not proposing it for 8.3 right?

I think I am. It's an important diagnostic for your other fix.

I agree, this is important for visibility into what's happening.
The string isn't getting translated so I don't see any big downside
to applying the patch in back branches.

regards, tom lane

On Fri, 2008-07-18 at 01:44 -0400, Tom Lane wrote:

Simon Riggs <simon@2ndquadrant.com> writes:

On Thu, 2008-07-17 at 17:10 -0400, Alvaro Herrera wrote:

I don't like your wording though; it feels too verbose (and you're
losing the ANALYZE in case it's doing both things). How about

snprintf(activity, MAX_AUTOVAC_ACTIV_LEN,
"autovacuum: VACUUM%s%s", vac
tab->at_doanalyze ? " ANALYZE" : "",
tab->at_wraparound ? " (wraparound)" : "");

Yes, looks good.

May I suggest "(to prevent wraparound)" or something like that?
Otherwise, +1.

You're not proposing it for 8.3 right?

I think I am. It's an important diagnostic for your other fix.

I agree, this is important for visibility into what's happening.
The string isn't getting translated so I don't see any big downside
to applying the patch in back branches.

Patches for 8.3 and CVS HEAD.

--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support

Simon Riggs wrote:

On Fri, 2008-07-18 at 01:44 -0400, Tom Lane wrote:

I agree, this is important for visibility into what's happening.
The string isn't getting translated so I don't see any big downside
to applying the patch in back branches.

Patches for 8.3 and CVS HEAD.

Applied, thanks.

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.