[pgpool-general: 5862] Re: Intermittent query failed when using pgpool2

Goh Geok Bee gbgoh at ntu.edu.sg
Tue Jan 16 16:35:10 JST 2018


Hi Tatsuo,

Those query are select query which old data that are already exist in both primary node and secondary nodes. So it should not be the case. 

Best Rdgs,
GB


-----Original Message-----
From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp] 
Sent: Tuesday, 16 January 2018 3:04 PM
To: Goh Geok Bee <gbgoh at ntu.edu.sg>
Cc: pgpool-general at pgpool.net
Subject: Re: [pgpool-general: 5853] Intermittent query failed when using pgpool2

That's pretty normal because streaming replication is essentially async process. A modification made on the primary node takes a while before it is applied to the standbys. If Pgpool-II redirects the query to standby, it is possible that it does not return the row you want to retrieve.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

> Hi Tatsuo,
> 
> Yes, it just returns no row. 
> 
> Best Rdgs,
> GB
> -----Original Message-----
> From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp]
> Sent: Tuesday, 16 January 2018 2:33 PM
> To: Goh Geok Bee <gbgoh at ntu.edu.sg>
> Cc: pgpool-general at pgpool.net
> Subject: Re: [pgpool-general: 5853] Intermittent query failed when 
> using pgpool2
> 
> After checking pgpool.conf and pgpool log, it seems everything is ok to me.
> 
>>> We are using pgpool2 version 3.6.7. However, we encountered intermittent query failed on our application and we are using parameterized query.
> 
> What did you see exactly by "query failed"? Any errors from your application? Or just it returns no row?
> 
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
> 
>> Hi Tatsuo,
>> 
>> Attached is the pgpool.conf. Looking forward to your reply. Thanks!
>> 
>> Best Rdgs,
>> GB
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> -----Original Message-----
>> From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp]
>> Sent: Friday, 12 January 2018 6:19 AM
>> To: Goh Geok Bee <gbgoh at ntu.edu.sg>
>> Cc: pgpool-general at pgpool.net
>> Subject: Re: [pgpool-general: 5853] Intermittent query failed when 
>> using pgpool2
>> 
>>> We are using pgpool2 version 3.6.7. However, we encountered intermittent query failed on our application and we are using parameterized query.
>>>
>>> We noticed there is similar issue reported in https://github.com/brianc/node-postgres/issues/513 too.
>>>
>>> We are using master/slave mode for pgpool with 1 master and 1 slave postgresql 9.6 servers and only load balance mode is enabled on pgpool2. I have attached the pgpool log file. Pls check the log for 10:57:16 onwards. The query that did not returned result is "SELECT version FROM qtemplates WHERE qtemplate = 17958;" . However, if the same query is run again, it maybe successful.
>>>
>>> Anyone has encountered this before? Appreciate any advice. Thanks!
>> 
>> Can you share pgpool.conf? Hard to tell what's going on without configuration data.
>> 
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese:http://www.sraoss.co.jp
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