Alexey Rodriguez Yakushev <alexey@serinbol.com> writes:
> Let me rephrase the question, i have a web-based application which uses
> postgres as its backend. It must be operating 24 hours 7 days. If i want to
> make a backup of the database using pg_dump, wouldn't it be possible that a
> transaction occurs in the middle of the backup, leaving the backup
> inconsistent?
No. pg_dump will produce a consistent snapshot that does not show the
effects of transactions that start (or complete) after the pg_dump
transaction starts. See the "multi-version concurrency control" chapter
of the User's Guide.
Postgres has its share of problems for 24x7 operation (read about VACUUM
if you haven't yet) ... but producing self-consistent backups is not
one of 'em.
regards, tom lane