[pgpool-general: 5866] Re: Intermittent query failed when using pgpool2

Goh Geok Bee gbgoh at ntu.edu.sg
Wed Jan 17 11:13:43 JST 2018


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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