Re: [HACKERS] partial indexes and bitmap scans

2017-03-09 Thread Tom Lane
Stephen Frost writes: > * Tom Lane (t...@sss.pgh.pa.us) wrote: >> I do notice that createplan.c makes some effort to get rid of filter >> conditions that are provably true when the index conditions are. >> Doesn't look like it considers the reverse direction. Not sure if >>

Re: [HACKERS] partial indexes and bitmap scans

2017-03-09 Thread Stephen Frost
Tom, * Tom Lane (t...@sss.pgh.pa.us) wrote: > Stephen Frost writes: > > We have already figured out that the user's predicate results in a > > subset of the index's or we wouldn't be able to use that index though, > > right? Do we really need to spend cycles re-discovering

Re: [HACKERS] partial indexes and bitmap scans

2017-03-09 Thread Tom Lane
Stephen Frost writes: > We have already figured out that the user's predicate results in a > subset of the index's or we wouldn't be able to use that index though, > right? Do we really need to spend cycles re-discovering that? Are > there cases where we actually need the

Re: [HACKERS] partial indexes and bitmap scans

2017-03-09 Thread Stephen Frost
Tom, * Tom Lane (t...@sss.pgh.pa.us) wrote: > Stephen Frost writes: > > Perhaps I'm missing something obvious, but isn't it a bit redundant to > > have both a Recheck condition (which is the predicate of the index) and > > a Filter condition (which is the user's predicate)

Re: [HACKERS] partial indexes and bitmap scans

2017-03-09 Thread Tom Lane
Stephen Frost writes: > Perhaps I'm missing something obvious, but isn't it a bit redundant to > have both a Recheck condition (which is the predicate of the index) and > a Filter condition (which is the user's predicate) when we've already > decided that the user's predicate