On Oct 27, 2004, at 0:57, TTK Ciar wrote:

  At a guess, it looks like the data set is being buffered in its
entirety by psql, before any data is written to the output file,
which is surprising.  I would have expected it to grab data as it
appeared on the socket from postmaster and write it to disk.  Is
there something we can do to stop psql from buffering results?
Does anyone know what's going on here?

Yes, the result set is sent back to the client before it can be used. An easy workaround when dealing with this much data is to use a cursor. Something like this:

db# start transaction;
db# declare logcur cursor for select * from some_table;
db# fetch 5 in logcur;
(5 rows)

This will do approximately what you expected the select to do in the first, place, but the fetch will decide how many rows to buffer into the client at a time.

  If the solution is to just write a little client that uses perl
DBI to fetch rows one at a time and write them out, that's doable,
but it would be nice if psql could be made to "just work" without
the monster RSS.

It wouldn't make a difference unless that driver implements the underlying protocol on its own.

SPY                      My girlfriend asked me which one I like better.
pub  1024/3CAE01D5 1994/11/03 Dustin Sallings <[EMAIL PROTECTED]>
|    Key fingerprint =  87 02 57 08 02 D0 DA D6  C8 0F 3E 65 51 98 D8 BE
L_______________________ I hope the answer won't upset her. ____________

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