Re: Reduce WAL logging of INSERT SELECT

Jaime Casanova <jaime@2ndquadrant.com> writes:
> On Sat, Aug 6, 2011 at 11:05 AM, Heikki Linnakangas
> <heikki.linnakangas@enterprisedb.com> wrote:
>> It can be very helpful when loading a lot of data, so I'm not in favor of
>> removing it altogether. Maybe WAL-log the first 10000 rows or such normally,
>> and skip WAL after that. Of course, loading 10001 rows becomes the worst
>> case then, but something along those lines...

> why 10000 rows?

Yeah; any particular number is wrong.  Perhaps it'd be better to put the
behavior under user control.  In the case of COPY, where we already have
a place to stick random options, you could imagine writing something
like
COPY ... WITH (bulk)

to cue the system that a lot of data is coming in.  But I don't see any
nice way to do something similar for INSERT/SELECT.  I hesitate to
suggest a GUC, but something like "SET bulk_load = on" would be pretty
straightforward to use in pg_dump for instance.
        regards, tom lane