Re: tablespace to benefit from ssd ?

Unless this is about reads exclusively I would start with putting wal on
ssd.
What you might also do, is create separate filesystems (lvm). You can then
keep track of io with iostat per filesystem and see what would benefit
most. And see storage size usage also.
And you could use lvm to move filesystems to and from ssd hot. So just
downtime once.

Please share your end findings in this thread too.

Op wo 19 feb. 2020 om 04:42 schreef Nicolas PARIS <nicolas(dot)paris(at)riseup(dot)net>

> Hi
>
> I have both hdd and ssd disk on the postgres server. The cluster is
> right now created on the hdd only. I am considering using a tablespace
> to put some highly used postgres object on the ssd disk. Of course the
> ssd is small compared to the hdd, and I need to choose carefully what
> objects are stored on that side.
>
> I am wondering what kind of object (indexes, data) would benefit from
> ssd. The database primary/foreign keys are highly used and there is
> almost no sequencial scan. However the server has a large amount of ram
> memory and I suspect all of those indexes are already cached in ram.
>
> I have read that tablespaces introduce overhead of maintenance and
> introduce complication for replication. But on the other hand I have
> this ssd disk ready for something.
>
> Any recommandation ?
>
> --
> nicolas paris
>
>
> --

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