[pgpool-general: 2326] Re: thousands of queries to pg_class / second

[Tatsuo Ishii]

> ok thanks,
> 
> I have disabled the check_temp_table as we don't use temp tables which
> removes the pg_temp queries, however there is still alot of queries for
> SELECT count(*) FROM pg_catalog.pg_class AS c WHERE c.relname = 'table' AND
> c.relpersistence = 'u' to me this seems like a check to see if the table
> exists, is there a way to cache this ?

I thought this one is cached. Can you show me pgpool.log with
log_per_node_statement enabled?
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> *Nathan Brennan* *BCS*
> Lead Developer
> 
> *T:* +61 8 9482 3981 | *E:* nathan at healthengine.com.au
> 
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> 
> 
> 
> On Wed, Dec 4, 2013 at 12:51 PM, Tatsuo Ishii <ishii at postgresql.org> wrote:
> 
>> > Hi,
>> >
>> > Is there a way to cache these queries or turn them off as pgpool is doing
>> > thousands of them a second.I tried setting relcache_expire=60 but it
>> > doesn't seem to help.
>> >
>> > example queries:
>> >
>> > SELECT count(*) FROM pg_class AS c, pg_namespace AS n WHERE c.relname =
>> > 'table' AND c.relnamespace = n.oid AND n.nspname = 'pg_catalog'
>> >  SELECT count(*) FROM pg_class AS c, pg_namespace AS n WHERE c.relname =
>> > 'table' AND c.relnamespace = n.oid AND n.nspname ~ '^pg_temp_'
>>
>> You can avoid temp table related queries by turning check_temp_table
>> to off (of course you need to be sure that you are not using temp
>> tables).
>>
>> Also relcache_expire = 0 will be more effective if you want to reduce
>> the number of queries.
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese: http://www.sraoss.co.jp
>>