On Wed, Nov 29, 2017 at 11:55 PM, Thomas Munro <thomas.mu...@enterprisedb.com> wrote: > Thank you for the original pointer and the commit. Everything here > seems to make intuitive sense and the accompanying throw-away tests > that I posted above seem to produce sensible results except in some > cases that we discussed, so I think this is progress. There is still > something pretty funny about the cardinality estimates for TPCH Q21 > which I haven't grokked though. I suspect it is crafted to look for a > technique we don't know (an ancient challenge set by some long retired > database gurus back in 1992 that their RDBMSs know how to solve, > hopefully not in the manner of a certain car manufacturer's air > pollution tests), but I haven't yet obtained enough round tuits to dig > further. I will, though.
Hmm, do you have an example of the better but still-funky estimates handy? Like an EXPLAIN plan? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
