[pgpool-general: 5867] Re: Intermittent query failed when using pgpool2

Tatsuo Ishii ishii at sraoss.co.jp
Wed Jan 17 11:20:18 JST 2018


I meant you execute "SELECT count(version) FROM qtemplates WHERE
qtemplate = 17958;" via Pgpool-II. Did you try that?

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,
> 
> Both nodes return 1 row. So there is something wrong with pgpool2? Thanks!
> 
> Best Rdgs,
> GB
>  
> 
> -----Original Message-----
> From: Tatsuo Ishii [mailto:ishii at sraoss.co.jp] 
> Sent: Wednesday, 17 January 2018 8:23 AM
> To: Goh Geok Bee <gbgoh at ntu.edu.sg>
> Cc: ishii at sraoss.co.jp; pgpool-general at pgpool.net
> Subject: Re: [pgpool-general: 5853] Intermittent query failed when using pgpool2
> 
> But the log shows "SELECT version FROM qtemplates WHERE qtemplate = 17958;" returns no rows on DB node 1. If you issue a query something like "SELECT count(version) FROM qtemplates WHERE qtemplate = 17958;"
> and see no rows returned, then there's something wrong with Pgpool-II.
> If it returns 1 row, then Pgpool-II is ok and probably you should check your PostgreSQL cluster on node 1.
> 
> 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,
>> 
>> 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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