From: | Yan Cheng CHEOK <yccheok(at)yahoo(dot)com> |
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To: | pgsql-general(at)postgresql(dot)org |
Subject: | Increasing checkpoint_segments - Any bad thing might happen? |
Date: | 2010-05-10 00:54:39 |
Message-ID: | 528940.67520.qm@web65704.mail.ac4.yahoo.com |
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Lists: | pgsql-general |
I realize that, when I have 1 threads perform frequent read, and another 3 threads to perform frequent write. I will get the following error log *sometimes*
2010-05-07 17:16:10 MYT LOG checkpoints are occurring too frequently (22 seconds apart)
2010-05-07 17:16:10 MYT HINT Consider increasing the configuration parameter "checkpoint_segments".
2010-05-07 17:31:37 MYT LOG checkpoints are occurring too frequently (29 seconds apart)
2010-05-07 17:31:37 MYT HINT Consider increasing the configuration parameter "checkpoint_segments".
My observation is, even the above logging happen, "write" operation is success when I exam the content of database.
What happen is that, the read operation fail.
read thread is spawned after 3 write threads, and read thread will only be considered as "success", only when its read result is same as what is being written by the 3 threads. The read threads will perform retry for every 200ms, lasted for 4 seconds.
I was thinking, what is the consequent of increasing "checkpoint_segments", say, from 3 to 6. Any bad thing might happen?
Thanks and Regards
Yan Cheng CHEOK
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