Re: Minor performance improvement in transition to external sort

From: Jeremy Harris <jgh(at)wizmail(dot)org>
To: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Minor performance improvement in transition to external sort
Date: 2014-02-07 21:28:00
Message-ID: 52F54FE0.8040408@wizmail.org
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On 06/02/14 22:12, Jeremy Harris wrote:
>> Did you try sorting already-sorted, reverse
>> sorted, or pipe-organ shaped data sets?

Summary (low numbers better):

Random ints: 83% compares, level on time.
Sorted ints: level compares, 70% time.
Reverse-sorted ints: 10% compares, 15% time (!)
Constant ints: 200% compares, 360% time (ouch, and not O(n))
Pipe-organ ints: 80% compares, 107% time
Random text: 83% compares, 106% time

--
Cheers,
Jeremy

Attachment Content-Type Size
siftdown_performance.ods application/vnd.oasis.opendocument.spreadsheet 24.3 KB

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