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Re: Auto-clustering?

From: Filip Rembiałkowski <filip(dot)rembialkowski(at)gmail(dot)com>
To: Marti Raudsepp <marti(at)juffo(dot)org>
Cc: Royce Ausburn <royce(at)inomial(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Auto-clustering?
Date: 2010-12-17 10:19:36
Message-ID: AANLkTikKC44GqDdbRuxUGGyCyQF8YjB+i71Mgu3Ee3Cm@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
you are right, I must have missed it...

                 Table "public.u"
 Column |            Type             | Modifiers
--------+-----------------------------+-----------
 id     | integer                     |
 t      | timestamp without time zone |
 d      | text                        |
Indexes:
    "u_d" btree (d)
    "u_id" btree (id)
    "u_t" btree (t)

filip(at)filip=# select oid, relname, pg_Relation_size(oid) from pg_class where
relname in('u','u_id','u_t','u_d');
  oid  | relname | pg_relation_size
-------+---------+------------------
 64283 | u       |         15187968
 64289 | u_id    |          6758400
 64290 | u_t     |          6086656
 64291 | u_d     |         16482304

filip(at)filip=# CLUSTER u USING u_t;
CLUSTER
filip(at)filip=# select oid, relname, pg_Relation_size(oid) from pg_class where
relname in('u','u_id','u_t','u_d');
  oid  | relname | pg_relation_size
-------+---------+------------------
 64283 | u       |         12115968
 64289 | u_id    |          3391488
 64290 | u_t     |          3391488
 64291 | u_d     |          8216576
(4 rows)


So CLUSTER is effectively CLUSTER + REINDEX... nice.


W dniu 17 grudnia 2010 10:41 użytkownik Marti Raudsepp <marti(at)juffo(dot)org>napisał:

> 2010/12/17 Filip Rembiałkowski <filip(dot)rembialkowski(at)gmail(dot)com>:
> > regarding clustering: it does not help with index bloat.
>
> I'm almost sure it does, CLUSTER re-creates all indexes from scratch
> after copying the tuples.
>
> Regards,
> Marti
>

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