Re: I don't understand this explain output

thanks for the answer, I forgot to mention that I did
enable autovacuum in postgresql.conf a while ago.
(autovacuum = on). But that did not seem to help.

I will run autovacuum full tonight. So the cost means
the total number of records to read including deleted ones?

Ron

Frank Bax schreef:
> Ron Arts wrote:
>> m=# explain select * from queue;
>> QUERY PLAN
>> ------------------------------------------------------------
>> Seq Scan on queue (cost=0.00..635477.00 rows=1 width=402)
>> (1 row)
>>
>> The cost seems to be very high. It's a small table (only 23 rows)
>> and has not seen many modifications since the table was initially
>> filled. OTOH many individual records are updated every minute.
>
>
>
> Then the inidividual records have been updated 635,477 times; because
> that's how many rows are really in the table. Each time a record is
> updated, the old one is still in database and a new one is added. Run
> "VACUUM FULL ANALYSE" on a regular basis to remove the obsolete records
> from table and recover disk space.
>
> Since 8.1, there is an optional feature called autovacuum.
>

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