A typical db may do index scan on disk, which requires several times as many io ... | Hacker News

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		olavgg on May 6, 2018 \| parent \| context \| favorite \| on: Intel's New Optane 905P Is the Fastest SSD A typical db may do index scan on disk, which requires several times as many io operations per 8kb (Postgresql/Oracle size) page compared to seq scan. These are executed with low queue depth.

anarazel on May 6, 2018 [–]

OTOH there's concurrency and prefetching logic increasing average queue depth.

olavgg on May 7, 2018 | [–]

Are index scans supposed to be faster with prefetch? It is random read at 8kb. I usually set read_ahead_kb to 8kb on disks/tablespaces for indexes.

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