Re: [ADMIN] Vacuum error on database postgres - Mailing list pgsql-hackers

From Joshua D. Drake
Subject Re: [ADMIN] Vacuum error on database postgres
Date
Msg-id 45097CF4.7040409@commandprompt.com
Whole thread Raw
In response to Re: [ADMIN] Vacuum error on database postgres  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [ADMIN] Vacuum error on database postgres  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
> This behavior dates from a time when there was no good alternative.
> One possible fix today would be to make ANALYZE take
> ShareUpdateExclusive lock instead, thus ensuring there is only one
> ANALYZE at a time on a table.  However I'm a bit concerned by the
> possibility that ANALYZE-inside-a-transaction could accumulate a
> whole bunch of such locks in a random order, leading at least to
> a risk of deadlocks against other ANALYZEs.  (We have to hold the
> lock till commit, else we aren't fixing the problem.)  Do we need a
> specialized lock type just for ANALYZE?  Would sorting the target
> list of rel OIDs be enough?  Perhaps it's not worth worrying about?
> 

Why not an internal lock that people don't see? The behavior would the 
following:

conn1: analyze foo;

conn2: analyze foo;

ERROR: analyze already running on foo

conn1: analyze foo;
conn2: analyze;

NOTICE: analyze full started, analyze running on foo, skipping foo

Sincerely,

Joshua D. Drake



>             regards, tom lane
> 
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