Re: Compression of full-page-writes

On 2013-09-11 19:39:14 +0900, Fujii Masao wrote:
> * Benchmark
> pgbench -c 32 -j 4 -T 900 -M prepared
> scaling factor: 100
>
> checkpoint_segments = 1024
> checkpoint_timeout = 5min
> (every checkpoint during benchmark were triggered by checkpoint_timeout)
>
> * Result
> [tps]
> 1344.2 (full_page_writes = on)
> 1605.9 (compress)
> 1810.1 (off)
>
> [the amount of WAL generated during running pgbench]
> 4422 MB (on)
> 1517 MB (compress)
> 885 MB (off)
>
> [time required to replay WAL generated during running pgbench]
> 61s (on) .... 1209911 transactions were replayed,
> recovery speed: 19834.6 transactions/sec
> 39s (compress) .... 1445446 transactions were replayed,
> recovery speed: 37062.7 transactions/sec
> 37s (off) .... 1629235 transactions were replayed,
> recovery speed: 44033.3 transactions/sec

ISTM for those benchmarks you should use an absolute number of
transactions, not one based on elapsed time. Otherwise the comparison
isn't really meaningful.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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