Re: Compression of full-page-writes

On Fri, Aug 30, 2013 at 11:55 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> My idea is very simple, just compress FPW because FPW is
> a big part of WAL. I used pglz_compress() as a compression method,
> but you might think that other method is better. We can add
> something like FPW-compression-hook for that later. The patch
> adds new GUC parameter, but I'm thinking to merge it to full_page_writes
> parameter to avoid increasing the number of GUC. That is,
> I'm thinking to change full_page_writes so that it can accept new value
> 'compress'.
Instead of a generic 'compress', what about using the name of the
compression method as parameter value? Just to keep the door open to
new types of compression methods.

> * Result
> [tps]
> 1386.8 (compress_backup_block = off)
> 1627.7 (compress_backup_block = on)
>
> [the amount of WAL generated during running pgbench]
> 4302 MB (compress_backup_block = off)
> 1521 MB (compress_backup_block = on)
>
> At least in my test, the patch could reduce the WAL size to one-third!
Nice numbers! Testing this patch with other benchmarks than pgbench
would be interesting as well.
--
Michael