[GENERAL] why pg_dump eats so much memory?

[Cristóvão Dalla Costa]

I just noticed that when I run pg_dump to backup my databases it will use
enormous amounts of memory, eating over 70 MB and causing the system to
trash. Then after a while it'll shrink to about 30MB, then grow again, and
repeat the cycle a couple times. The database has 3 tables with araound
350,000 rows, and one table with 1,300,000 rows.

I would like to know the causes of that behaviour, and, hopefully, how I can
fix it. I'm running 7.0.2 on freebsd 4.1.

Thanks!