Thanks for the info. on bcache etc., first time heard about it. But it seems quite coarse grained for the needs of a database. The closest thing might be this implemented by the RocksDB engine: https://github.com/facebook/rocksdb/wiki/Persistent-Read-Cache On Mon, Feb 12, 2018 at 9:18 AM, Steve Atkins <steve@xxxxxxxxxxx> wrote: > >> On Feb 11, 2018, at 5:14 PM, Sand Stone <sand.m.stone@xxxxxxxxx> 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 > > >
