From: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
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To: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
Cc: | postgres performance list <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: PSA: upgrade your extensions |
Date: | 2017-02-02 12:24:52 |
Message-ID: | CAHyXU0z+k2nr0C-4KvwtwbmFW+Ya4WiK2rRRw4uWUpM89G9S+A@mail.gmail.com |
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Lists: | pgsql-performance |
On Thu, Feb 2, 2017 at 1:18 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> On Wed, Feb 1, 2017 at 4:38 AM, Merlin Moncure <mmoncure(at)gmail(dot)com> wrote:
>>
>> I was just troubleshooting a strange performance issue with pg_trgm
>> (greatest extension over) that ran great in testing but poor in
>> production following a 9.6 in place upgrade from 9.2. By poor I mean
>> 7x slower. Problem was resolved by ALTER EXTENSION UPDATE followed by
>> a REINDEX on the impacted table. Hope this helps somebody at some
>> point :-).
>
> It was probably the implementation of the triconsistent function for pg_trgm
> (or I would like to think so, anyway).
Yeah, this is definitely the case. We are seeing 50-80% runtime
reduction in many common cases, with the problematic cases being in
the upper end of that range.
> But if so, the REINDEX should not have been necessary, just the ALTER
> EXTENSION UPDATE should do the trick. Rebuiding a large gin index can be
> pretty slow.
Hm, I thought it *was* necessary, in my poking. However the evidence
is destroyed and it's not worth restaging the test, so I'll take your
word for it.
merlin
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