Re: Performance on large data transformations

Josh Berkus wrote:
>
>There is, for that matter, no kernel swap activity, but I'm not
>sure how to measure Postgres temp file activity.

Of course you could:

   mv /wherever/data/base/16556/pgsql_tmp /some_other_disk/
   ln -s /some_other_disk/pgsql_tmp /wherever/data/base/16556

and use "iostat" from the "systat" package to watch how much you're
using the disk the temp directory's on.


In fact, for OLAP stuff I've had this help performance because
quite a few data warehousing operations look like:
   First read from main database,
   do a big hash-or-sort, (which gets written to pgsql_tmp),
   then read from this temporary table and write result to main database

PS: Yes, I know this doesn't help the FSM stuff you asked about.


    Ron