Re: [HACKERS] AdvanceXLInsertBuffer vs. WAL segment compressibility - Mailing list pgsql-hackers

From Michael Paquier
Subject Re: [HACKERS] AdvanceXLInsertBuffer vs. WAL segment compressibility
Date
Msg-id CAB7nPqSGYEngZuUU8fmeFo5c3hcYFpPKwO12mU1yngwDC=KS9A@mail.gmail.com
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In response to Re: [HACKERS] AdvanceXLInsertBuffer vs. WAL segment compressibility  (Chapman Flack <chap@anastigmatix.net>)
List pgsql-hackers
On Fri, Jun 23, 2017 at 6:08 AM, Chapman Flack <chap@anastigmatix.net> wrote:
> Well, gzip was doing pretty well; it could get a 16 MB segment file down
> to under 27 kB, or less than 14 bytes for each of 2000 pages, when a page
> header is what, 20 bytes, it looks like? I'm not sure how much better
> I'd expect a (non-custom) compression scheme to do. The real difference
> comes between compressing (even well) a large unchanged area, versus being
> able to recognize (again with a non-custom tool) that the whole area is
> unchanged.

Have you tried as well lz4 for your cases? It performs faster than
gzip at minimum compression and compresses less, but I am really
wondering if for almost zero pages it performs actually better.
-- 
Michael



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