On Mon, May 5, 2008 at 6:18 AM, Hans Zaunere <lists@xxxxxxxxxxx> wrote: > > > We're using a statement like this to dump between 500K and >5 million > > > rows. > > > > > COPY(SELECT SomeID FROM SomeTable WHERE SomeColumn > '0') > > > TO '/dev/shm/SomeFile.csv' > > > > > Upon first run, this operation can take several minutes. Upon second > > > run, it will be complete in generally well under a minute. > > > > Hmmm ... define "first" versus "second". What do you do to return it > > to the slow state? > > Interesting that you ask. I haven't found a very reliable way to reproduce > this. > > Typically, just waiting a while to run the same query the second time will > reproduce this behavior. I restarted postgresql and it was reproduced as > well. However, I can't find a way to flush buffers/etc, to reproduce the what happens if you do something like: select count(*) from (select ...); i.e. don't make the .csv file each time. How's the performance without making the csv versus making it?
