From: | Andres Freund <andres(at)anarazel(dot)de> |
---|---|
To: | Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com>,Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
Cc: | Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com>,Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>,David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>,Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: ALTER TABLE ADD COLUMN fast default |
Date: | 2018-02-20 17:43:45 |
Message-ID: | 86776DEA-C622-4085-BCF3-C9F5E9034978@anarazel.de |
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Lists: | pgsql-hackers |
On February 20, 2018 5:03:58 AM PST, Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com> wrote:
>On 20/02/18 07:42, Andres Freund wrote:
>> Hi,
>>
>> On 2018-02-17 00:23:40 +0100, Tomas Vondra wrote:
>>> Anyway, I consider the performance to be OK. But perhaps Andres
>could
>>> comment on this too, as he requested the benchmarks.
>>
>> My performance concerns were less about CREATE TABLE related things
>than
>> about analytics workloads or such, where deforming is the primary
>> bottleneck. I think it should be ok, but doing a before/after tpc-h
>of
>> scale 5-10 or so wouldn't be a bad thing to verify.
>>
>
>The test Tomas is doing is analytical query, it's running sum on the
>new
>fast default column.
>
>He uses create and create-alter names as comparison between when the
>table was created with the columns and when the columns were added
>using
>fast default.
It's still a fairly simplistic test case. Running some queries with reasonably well known characteristics seems like a good idea regardless. It's not like a scale 5 run takes that long.
Andres
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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