Re: PROC_IN_ANALYZE stillborn 13 years ago - Mailing list pgsql-hackers

From Andres Freund
Subject Re: PROC_IN_ANALYZE stillborn 13 years ago
Date
Msg-id 20200806212632.r7zl7fvu2s737lsx@alap3.anarazel.de
Whole thread Raw
In response to Re: PROC_IN_ANALYZE stillborn 13 years ago  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
Hi,

On 2020-08-06 14:48:52 -0400, Robert Haas wrote:
> On Thu, Aug 6, 2020 at 2:37 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > +1 for removal.  It's not clear to me that we'd ever put it back.
> > Long-running ANALYZE snapshots are indeed a problem, but Simon's proposal
> > upthread to just take a new one every so often seems like a much cleaner
> > and simpler answer than having onlookers assume that it's safe to ignore
> > ANALYZE processes.  (Given that ANALYZE can invoke user-defined functions,
> > and can be invoked from inside user transactions, any such assumption
> > seems horribly dangerous.
> 
> Not to get too far from the proposal on the table of just removing
> something that's been unused for a really long time, which stands on
> its own merits, but if a particular ANALYZE doesn't invoke any
> user-defined functions and isn't run inside a transaction, could we
> skip acquiring a snapshot altogether? That's an extremely common case,
> though by no means universal.

I don't think so, at least not in very common situations. E.g. as long
as there's a toast table we need to hold a snapshot to ensure that we
don't get failures looking up toasted datums. IIRC there were some other
similar issues that I can't quite recall right now.

Greetings,

Andres Freund



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