Re: Proposed patch to change TOAST compression strategy - Mailing list pgsql-patches

From Tom Lane
Subject Re: Proposed patch to change TOAST compression strategy
Date
Msg-id 8565.1204932192@sss.pgh.pa.us
Whole thread Raw
In response to Re: Proposed patch to change TOAST compression strategy  (Gregory Stark <stark@enterprisedb.com>)
List pgsql-patches
Gregory Stark <stark@enterprisedb.com> writes:
> "Tom Lane" <tgl@sss.pgh.pa.us> writes:
>> * Adds an early-failure path to the compressor as suggested by Jan:
>> if it's been unable to find even one compressible substring in the
>> first 1KB (parameterizable), assume we're looking at incompressible
>> input and give up.  (There are various ways this could be done, but
>> this way seems to add the least overhead to the compressor's inner
>> loop.)

> I'm not sure how to test the rest of it, but this bit seems testable. I fear
> this may be too conservative. Even nigh incompressible data will find a few
> backreferences.
> I'll try some tests and see.

On the strength of Teodor's favorable test, I went ahead and applied
this patch as-is.  We can certainly tweak the compressor logic again
if you can show an improvement by changing it further.

            regards, tom lane

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