"Kevin Grittner" <Kevin.Grittner@xxxxxxxxxxxx> writes: > We are replicating data from 72 source databases, each with the > official copy of a subset of the data, to four identical consolidated > databases, spread to separate locations, to serve our web site and other > organization-wide needs. Currently, two of these central databases are > running a commercial product and two are running PostgreSQL. There have > been several times that I have run a SELECT COUNT(*) on an entire table > on all central machines. On identical hardware, with identical data, > and equivalent query loads, the PostgreSQL databases have responded with > a count in 50% to 70% of the time of the commercial product, in spite of > the fact that the commercial product does a scan of a non-clustered > index while PostgreSQL scans the data pages. Interesting. I think though that the people who are complaining come from databases where COUNT(*) takes constant time because the DB keeps a running count in the table's metadata. regards, tom lane
