Thread: Question for the developers.

Question for the developers.

From
suchindra@linuxlabs.com
Date:
Hi,
I am Suchindra Katageri and am working as a Software Engineer atLinuxlabs, Atlanta, GA.I am presently working on
developinglibraries to make postgresqlrun on a cluster. I was wondering if it was possible to force Databasewrites to
stablestorage, without messing up with the postgres code.e.g. force the PostgreSQL to write to stable storage after an
INSERTcommand.
Thanks in advance.
-- 
regards,
--suchindra



Re: Question for the developers.

From
Bruce Momjian
Date:
suchindra@linuxlabs.com wrote:
> 
> Hi,
> 
>  I am Suchindra Katageri and am working as a Software Engineer at
>  Linuxlabs, Atlanta, GA.
>  
>  I am presently working on developing libraries to make postgresql
>  run on a cluster. I was wondering if it was possible to force Database
>  writes to stable storage, without messing up with the postgres code.
>  e.g. force the PostgreSQL to write to stable storage after an INSERT
>  command.

For stable storage, you mean disk storage?  You need fsync for that,
probably, but we already fsync our write-ahead log (WAL) on every
commit.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
359-1001+  If your life is a hard drive,     |  13 Roberts Road +  Christ can be your backup.        |  Newtown Square,
Pennsylvania19073
 


Re: Question for the developers.

From
Jan Wieck
Date:
suchindra@linuxlabs.com wrote:

> Hi,
> 
>  I am Suchindra Katageri and am working as a Software Engineer at
>  Linuxlabs, Atlanta, GA.
>  
>  I am presently working on developing libraries to make postgresql
>  run on a cluster. I was wondering if it was possible to force Database
>  writes to stable storage, without messing up with the postgres code.
>  e.g. force the PostgreSQL to write to stable storage after an INSERT
>  command.

I don't see how that would help you very far.

PostgreSQL holds disk buffers in a shared memory cache. And unless you 
modify that cache, it would not read from the file again if it thinks it 
knows the content already. How do you intend to remove pages from that 
shared buffer cache at the time, another cluster member modifies the 
same logical page?


Jan

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