Re: By now, why PostgreSQL 9.2 don't support SSDs?
От | Ants Aasma |
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Тема | Re: By now, why PostgreSQL 9.2 don't support SSDs? |
Дата | |
Msg-id | CA+CSw_ucSZ5KAJoZiYqWUpfPWtqZvQAj0M+W66BVvfJgHNFacQ@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: By now, why PostgreSQL 9.2 don't support SSDs? (Satoshi Nagayasu <snaga@uptime.jp>) |
Список | 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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