On Fri, Aug 24, 2012 at 2:16 PM, Tomas Vondra <t...@fuzzy.cz> wrote: > Hi, > > attached is a patch that adds support for random sampling in pgbench, when > it's executed with "-l" flag. You can do for example this: > > $ pgbench -l -T 120 -R 1 db > > and then only 1% of transactions will be written into the log file. If you > omit the tag, all the transactions are written (i.e. it's backward > compatible).
Hi Tomas, You use the rand() function. Isn't that function not thread-safe? Or, if it is thread-safe, does it accomplish that with a mutex? That was a problem with a different rand function used in pgbench that Robert Haas fixed a while ago, 4af43ee3f165c8e4b332a7e680. Also, what benefit is had by using modulus on rand(), rather than just modulus on an incrementing counter? Could you explain the value of this patch, given your other one that does aggregation? If both were accepted, I think I would always use the aggregation one in preference to this one. Thanks, Jeff -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers