The following bug has been logged online:
Bug reference: 4964
Logged by: jasen Betts
Email address: jasen(at)xnet(dot)co(dot)nz
PostgreSQL version: 8.3
Operating system: linux
Description: return value does not agree with documentation
Details:
PQsendQuery() seems to return 0 on success and 1 on failure contrary to the
documented behavior.
http://www.postgresql.org/docs/8.3/interactive/libpq-async.html