| From: | Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com> |
|---|---|
| To: | Marcos Garcia <marcos-p-garcia(at)ptinovacao(dot)pt> |
| Cc: | pgsql-sql <pgsql-sql(at)postgresql(dot)org> |
| Subject: | Re: Slow SELECT with distinct, in a TIMESTAMP type column |
| Date: | 2002-06-24 18:36:56 |
| Message-ID: | 20020624113546.R56100-100000@megazone23.bigpanda.com |
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| Thread: | |
| Lists: | pgsql-sql |
On 24 Jun 2002, Marcos Garcia wrote:
> The problem is that my query is too slow when i use distinct:
>
> pgsql> explain analyze SELECT distinct(smsdate) FROM send_total;
>
> NOTICE: QUERY PLAN:
>
> Unique (cost=15840.31..15870.81 rows=1220 width=8) (actual
> time=56358.93..56452.78 rows=6670 loops=1)
> -> Sort (cost=15840.31..15840.31 rows=12203 width=8) (actual
> time=56358.91..56436.95 rows=12062 loops=1)
> -> Seq Scan on send_total (cost=0.00..15012.03 rows=12203
> width=8) (actual time=0.55..56205.25 rows=12062 loops=1)
> Total runtime: 56518.26 msec
As a question, what does explain analyze show if you
set enable_seqscan=off; first?
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