Um... Oracle (and other enterprise databases like DB2) don't use mmap. They use ... | Hacker News

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		tytso on Jan 14, 2022 \| parent \| context \| favorite \| on: Are you sure you want to use MMAP in your database... Um... Oracle (and other enterprise databases like DB2) don't use mmap. They use Direct I/O. Oracle does have anonymous (non-file-backed) memory which is mmap'ed and shared across various Oracle processes, called the Shared Global Area (SGA), but it's not used for I/O.

hyc_symas on Jan 15, 2022 [–]

Fwiw, I wrote a Direct I/O patch for BerkeleyDB but withdrew it later because it didn't ever improve I/O perf or memory footprint.

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