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/PostgreSQL Development, 24x7 Support, Training &
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