Re: Postgres as In-Memory Database?

2013/11/18 Andreas Brandl <ml(at)3(dot)141592654(dot)de> wrote:
> What is your use-case?

It's geospatial data from OpenStreetMap stored in a schema optimized for
PostGIS extension (produced by osm2pgsql).

BTW: Having said (to Martijn) that using Postgres is probably more
efficient, than programming an in-memory database in a decent language:
OpenStreetMap has a very, very large Node table which is heavily used by
other tables (like ways) - and becomes rather slow in Postgres. Since it's
of fixed length I'm looking at file_fixed_length_record_fdw extension
[1][2] (which is in-memory) to get the best of both worlds.

--Stefan

[1]
http://wiki.postgresql.org/wiki/Foreign_data_wrappers#file_fixed_length_record_fdw
[2] https://github.com/adunstan/file_fixed_length_record_fdw

2013/11/18 Andreas Brandl <ml(at)3(dot)141592654(dot)de>

> Hi Stefan,
>
> > How can Postgres be used and configured as an In-Memory Database?
> >
>
> we've put the data directory on our buildserver directly on a ramdisk
> (e.g. /dev/shm) to improve build times.
>
> Obviously you then don't care too much about durability here, so one can
> switch off all related settings (as has already been pointed out). The only
> thing to do on a server reboot would be to re-create a fresh data directory
> on the ramdisk.
>
> So if you're able to start from scratch relatively cheap (i.e. on a server
> reboot), don't care about durability/crash safety at all and your database
> fits into ram that solution is easy to handle.
>
> I've also tried having only a separate tablespace on ramdisk but abandoned
> the idea because postgres seemed too surprised to see the tablespace empty
> after a reboot (all tables gone).
>
> Overall the above solution works and improves our build times but I think
> there are better ways to have in-memory/application caches than using a
> postgres.
>
> What is your use-case?
>
> Regards
> Andreas
>
>
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