Re: By now, why PostgreSQL 9.2 don't support SSDs? - Mailing list pgsql-hackers

From Ants Aasma
Subject Re: By now, why PostgreSQL 9.2 don't support SSDs?
Date
Msg-id CA+CSw_ucSZ5KAJoZiYqWUpfPWtqZvQAj0M+W66BVvfJgHNFacQ@mail.gmail.com
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In response to Re: By now, why PostgreSQL 9.2 don't support SSDs?  (Satoshi Nagayasu <snaga@uptime.jp>)
List pgsql-hackers
<p dir="ltr">On Mar 30, 2013 7:13 PM, "Satoshi Nagayasu" <<a href="mailto:snaga@uptime.jp">snaga@uptime.jp</a>>
wrote:<br/> > But I heard that larger block size, like 256kB, would take<br /> > advantage of the SSD performance
becauseof the block management<br /> > within SSD.<p dir="ltr">This is only true for very bad SSDs. Any SSD that you
wouldwant to trust with your data do block remapping internally, eliminating the issue. (See for example Intel DC3700
sustaining34'000 random 4k writes/s)<p dir="ltr">Larger block sizes would just lift the random access workload write
amplificationinto Postgresql  where the drive can't fix it. For sequential or mostly sequential workloads the OS can
takecare of it by merging writes. Additionally, contention for page level locks will increase with page size, cache
efficiencygoes down. I would expect cases where larger block size is a significant benefit to be very rare.<p
dir="ltr">Regards,<br/> Ants Aasma 

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