On Sun, Apr 14, 2019 at 09:45:10AM -0700, Andres Freund wrote:
Hi,
On 2019-04-14 18:36:18 +0200, Tomas Vondra wrote:
I think those comparisons are cute and we did a fair amount of them when
considering a drop-in replacement for pglz, but ultimately it might be a
bit pointless because:
(a) it very much depends on the dataset (one algorithm may work great on
one type of data, suck on another)
(b) different systems may require different trade-offs (high ingestion
rate vs. best compression ratio)
(c) decompression speed may be much more important
What I'm trying to say is that we shouldn't obsess about picking one
particular algorithm too much, because it's entirely pointless. Instead,
we should probably design the system to support different compression
algorithms, ideally at column level.
I think we still need to pick a default algorithm, and realistically
that's going to be used by like 95% of the users.
True. Do you expect it to be specific to the column store, or should be
set per-instance default (even for regular heap)?
FWIW I think the conclusion from past dev meetings was we're unlikely to
find anything better than lz4. I doubt that changed very much.
regard
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
