Hi, On 2019-02-18 19:01:06 -0500, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > Isn't a large portion of benefits in this patch going to be mooted by > > the locking improvements discussed in the other threads? I.e. there's > > hopefully not going to be a ton of cases with low overhead where we > > acquire a lot of locks and release them very soon after. Sure, for DDL > > etc we will, but I can't see this mattering from a performance POV? > > Mmm ... AIUI, the patches currently proposed can only help for what > David called "point lookup" queries. There are still going to be > queries that scan a large proportion of a partition tree, so if you've > got tons of partitions, you'll be concerned about this sort of thing.
Agreed - but it seems not unlikely that for those the rest of the planner / executor overhead will entirely swamp any improvement we could make here. If I understand correctly the benchmarks here were made with "point" update and select queries, although the reference in the first post in this thread is a bit vague. > > I'm not against doing something like Tom proposes, but heuristics with > > magic constants like this tend to age purely / are hard to tune well > > across systems. > > I didn't say it had to be a constant ... Do you have good idea? Greetings, Andres Freund