| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: alternative compression algorithms? |
| Date: | 2015-04-30 00:42:19 |
| Message-ID: | CA+Tgmoan+Zj-UrC29hqdp72ZZtFv7_4eh93FbEURAA1qDzBH9w@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Apr 29, 2015 at 6:55 PM, Tomas Vondra
<tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
> I'm not convinced not compressing the data is a good idea - it suspect it
> would only move the time to TOAST, increase memory pressure (in general and
> in shared buffers). But I think that using a more efficient compression
> algorithm would help a lot.
>
> For example, when profiling the multivariate stats patch (with multiple
> quite large histograms), the pglz_decompress is #1 in the profile, occupying
> more than 30% of the time. After replacing it with the lz4, the data are bit
> larger, but it drops to ~0.25% in the profile and planning the drops
> proportionally.
That seems to imply a >100x improvement in decompression speed. Really???
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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