| From: | Amit Kapila <amit(dot)kapila(at)huawei(dot)com> |
|---|---|
| To: | "'Samrat Revagade'" <revagade(dot)samrat(at)gmail(dot)com>, "'Hannu Krosing'" <hannu(at)2ndquadrant(dot)com>, "'Fujii Masao'" <masao(dot)fujii(at)gmail(dot)com> |
| Cc: | "'PostgreSQL-development'" <pgsql-hackers(at)postgresql(dot)org>, <sthomas(at)optionshouse(dot)com>, <ants(at)cybertec(dot)at>, <andres(at)2ndquadrant(dot)com> |
| Subject: | Re: Inconsistent DB data in Streaming Replication |
| Date: | 2013-04-10 12:03:23 |
| Message-ID: | 006301ce35e3$67b0a040$3711e0c0$@kapila@huawei.com |
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| Lists: | pgsql-hackers |
On Wednesday, April 10, 2013 3:42 PM Samrat Revagade wrote:
>>(5) The master then forces a write of the data page related to this
transaction.
> Sorry, this is incorrect. Whenever the master writes the data page it
checks that the WAL record is written in standby till that LSN.
>> While master is waiting to force a write (point 5) for this data page,
streaming replication continuous.
>> Also other data page writes are not dependent on this particular page
write. So the commit of data >pages are not serialized.
>Sorry, this is incorrect. Streaming replication continuous, master is not
waiting, whenever the master writes the data page it checks that the WAL
record is written in standby till that LSN.
I am not sure it will resolve the problem completely as your old-master can
have some WAL extra then new-master for same timeline. I don't remember
exactly will timeline switch feature
take care of this extra WAL, Heikki can confirm this point?
Also I think this can serialize flush of data pages in checkpoint/bgwriter
which is currently not the case.
With Regards,
Amit Kapila.
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