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A comment on ClickHouse cost-efficiency in action: analyzing 500B rows on an Intel NUC. Parent comment

Re:ClickHouse cost-efficiency in action: analyzing 500B rows... by DasIch on Monday January 06, 2020 @05:37PM (#21974265)
I can't find anything about this in the docs except[1]. I also can't find any issues in their bug tracker related to clickhouse not using fsync[2].

I can however find code that actually calls fsync[3][4]. To be fair I haven't read enough to determine how this (doesn't) affect durability. Nevertheless I'm wondering do you have a source for this claim?

  [1]: https://clickhouse.yandex/docs/en/operations/settings/settings/#fsync-metadata
  [2]: https://github.com/ClickHouse/ClickHouse/search?q=fsync&type=Issues
  [3]: https://github.com/ClickHouse/ClickHouse/blob/355b1e5594119e036a2d62988bfa42bc8b1a1687/dbms/src/IO/WriteBufferFromFileDescriptor.cpp#L113
  [4]: https://github.com/ClickHouse/ClickHouse/blob/e765733a26cfc4cecc13c981686560338256a6b1/dbms/src/IO/WriteBufferAIO.cpp#L98
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Re:ClickHouse cost-efficiency in action: analyzing 500B rows... by codexon on Monday January 06, 2020 @08:34PM (#21975810)
As I mentioned, there's only 1 place where it says anything about fsync, and in that page, it says that is only for creating .sql files.

https://groups.google.com/d/msg/clickhouse/cjJ6v8uzu0Q/jGV59...

> The reason is because CH does not use fsync (for performance)

https://www.linkedin.com/in/dzhuravlev/

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