Re: Mount database on RAM disk?

stuart(at)stuartbishop(dot)net (Stuart Bishop) writes:
> I'm putting together a road map on how our systems can scale as our
> load increases. As part of this, I need to look into setting up some
> fast read only mirrors of our database. We should have more than
> enough RAM to fit everything into memory. I would like to find out
> if I could expect better performance by mounting the database from a
> RAM disk, or if I would be better off keeping that RAM free and
> increasing the effective_cache_size appropriately.

If you were willing to take on a not-inconsiderable risk, I'd think
that storing WAL files on a RAMDISK would be likely to be the fastest
improvement imaginable.

If I could get and deploy some SSD (Solid State Disk) devices that
would make this sort of thing *actually safe,* I'd expect that to be a
pretty fabulous improvement, at least for write-heavy database
activity.

> I'd also be interested in knowing if this is dependant on whether I
> am running 7.4, 8.0 or 8.1.

Behaviour of all three could be somewhat different, as management of
the shared cache has been in flux...
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