Rados*aw Smogura<rsmog...@softperience.eu> wrote: > I have implemented initial concept of 2nd level cache. Idea is to > keep some segments of shared memory for special buffers (e.g. > indices) to prevent overwrite those by other operations. I added > those functionality to nbtree index scan. > > I tested this with doing index scan, seq read, drop system > buffers, do index scan and in few places I saw performance > improvements, but actually, I'm not sure if this was just "random" > or intended improvement. I've often wondered about this. In a database I developed back in the '80s it was clearly a win to have a special cache for index entries and other special pages closer to the database than the general cache. A couple things have changed since the '80s (I mean, besides my waistline and hair color), and PostgreSQL has many differences from that other database, so I haven't been sure it would help as much, but I have wondered. I can't really look at this for a couple weeks, but I'm definitely interested. I suggest that you add this to the next CommitFest as a WIP patch, under the Performance category. https://commitfest.postgresql.org/action/commitfest_view/open > There is few places to optimize code as well, and patch need many > work, but may you see it and give opinions? For something like this it makes perfect sense to show "proof of concept" before trying to cover everything. -Kevin
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