Re: [GENERAL] Why so long?
| От | Steve Clark |
|---|---|
| Тема | Re: [GENERAL] Why so long? |
| Дата | |
| Msg-id | 1016f7cc-3acf-b6ab-d1d4-cd29df85fe7b@netwolves.com обсуждение исходный текст |
| Ответ на | Re: [GENERAL] Why so long? (Jeff Janes <jeff.janes@gmail.com>) |
| Список | pgsql-general |
On 04/19/2017 11:57 AM, Jeff Janes wrote:
Hi Jeff,On Wed, Apr 19, 2017 at 8:24 AM, Steve Clark <steve.clark@netwolves.com> wrote:Hello,
I am confused. I have a table that has an incrementing primary key id.
When I select max(id) from table is returns almost instantly but
when I select min(id) from table it takes longer than I want to wait.
Shouldn't postgresql be able to quickly find the minimum id value in the index?Not if the low end of the index is stuffed full of obsolete entries, which haven't been cleaned up because it is not being vacuumed often enough.Do you have autovacuum on? Have you manually vacuumed the table recently?Cheers,Jeff
Autovacuum is turned on.
schemaname | relname | last_vacuum | last_autovacuum | vacuum_count | autovacuum_count
------------+-----------------------+-------------+-------------------------------+--------------+------------------
public | netflow | | 2017-04-11 01:18:53.261221-04 | 0 | 1
It is a large table.
select pg_size_pretty(pg_relation_size('netflow'));
pg_size_pretty
----------------
1267 GB
select pg_size_pretty(pg_total_relation_size('netflow_pkey'));
pg_size_pretty
----------------
287 GB
Regards,
Steve
Steve
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