Re: persistent read cache

> On Feb 11, 2018, at 5:14 PM, Sand Stone <sand(dot)m(dot)stone(at)gmail(dot)com> wrote:
>
>
> Hi. I wonder if there is such a thing or extension in the PG world.
>
> Here is my use case. I am using PG (PG10 to be more specific) in a
> cloud VM environment. The tables are stored in RAID0 managed SSD
> backed attached storage. Depending on the VM I am using, I usually
> have 256GB local SSD unused.
>
> I wonder if PG could leverage this local SSD as a read (page/block)
> cache, to complement/extend the DRAM by used by shared_buffer today.

It seems something that PostgreSQL could take advantage of, but
it's probably the wrong layer to implement it. If your VM infrastructure
doesn't have any way to use it directly, maybe you could do it at the
drive / filesystem level with something like bcache, lvmcache or
enhanceio?

Adding that sort of complexity to something that needs solid data
integrity makes me nervous, but those solutions have been in the
field for years.

Cheers,
Steve