Re: WIP patch: reducing overhead for repeat de-TOASTing

"Tom Lane" <tgl@sss.pgh.pa.us> writes:

> After playing with it for a little bit, I'm not convinced that it buys
> enough performance win to be worth applying --- the restriction of cache
> lifespan to one tuple cycle of a TupleTableSlot is awfully restrictive.
> (For example, sorts that involve toasted sort keys continue to suck,
> because the tuples being sorted aren't in Slots.)  It would probably
> fix the specific case that the PostGIS hackers were complaining of,
> but I think we need something more.
>
> Still, I wanted to get it into the archives because the idea of indirect
> toast pointers might be useful for something else.

I do like that it handles even inline-compressed cases. What I didn't like
about the managed cache was that it couldn't handle such cases. I could easily
imagine the PostGIS case arising for inline compressed data structures. I
wonder if it isn't worthwhile just for that case even if there's a further
cache behind it for repeated fetches of out-of-line data.

--  Gregory Stark EnterpriseDB          http://www.enterprisedb.com Ask me about EnterpriseDB's RemoteDBA services!