On 16 December 2015 at 09:51, Viktor Leis <l...@in.tum.de> wrote: > Hi, > > We have recently performed an experimental evaluation of PostgreSQL's > query optimizer. For example, we measured the contributions of > cardinality estimation and the cost model on the overall query > performance. You can download the resulting paper here: > http://www.vldb.org/pvldb/vol9/p204-leis.pdf
Thank you, an excellent contribution. > Some findings: > 1. Perhaps unsurprisingly, we found that cardinality > estimation is the biggest problem in query optimization. > 2. The quality of Postgres' cardinality estimates is not generally worse > than that of the major commerical systems. > Good to hear, though we have found problems there that alter plan selection adversely for TPC-H with the current optimizer. We have some improvements which may be in the next release. -- Simon Riggs http://www.2ndQuadrant.com/ <http://www.2ndquadrant.com/> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services