On Fri, 21 Jun 2024 07:12:25 +0000 <masahiro.ik...@nttdata.com> wrote:
> * Is this feature useful? Is there a possibility it will be accepted? I think adding such information to EXPLAIN outputs is useful because it will help users confirm the effect of a multicolumn index on a certain query and decide to whether leave, drop, or recreate the index, and so on. > * Are there any other ideas for determining if multicolumn indexes are > > being used efficiently? Although I considered calculating the efficiency using > > pg_statio_all_indexes.idx_blks_read and pg_stat_all_indexes.idx_tup_read, > > I believe improving the EXPLAIN output is better because it can be output > > per query and it's more user-friendly. It seems for me improving EXPLAIN is a natural way to show information on query optimization like index scans. > * Is "Index Bound Cond" the proper term?I also considered changing > > "Index Cond" to only show quals for the boundary condition and adding > > a new term "Index Filter". "Index Bound Cond" seems not intuitive for me because I could not find description explaining what this means from the documentation. I like "Index Filter" that implies the index has to be scanned. > * Would it be better to add new interfaces to Index AM? Is there any case > > to output the EXPLAIN for each index context? At least, I think it's worth > > considering whether it's good for amcostestimate() to modify the > > IndexPath directly as the PoC patch does. I am not sure it is the best way to modify IndexPath in amcostestimate(), but I don't have better ideas for now. Regards, Yugo Nagata > > > > > Regards, > > -- > > Masahiro Ikeda > > NTT DATA CORPORATION > > -- Yugo NAGATA <nag...@sraoss.co.jp>
