Tom Lane mentioned in this post that an empty query can be sent to the server to determine whether the connection is still good:
http://archives.postgresql.org/pgsql-hackers/2001-10/msg00643.php Is a query of "" guaranteed to work as long as the connection is good? What about ";" or " "? Background: I am maintaining some postgres client code (C++/libpq) that, during exception handling for a failed query, must determine whether the database connection is still good. This check is currently done by sending a "select version()" query and checking the result. However, even that simple query fails with PGRES_FATAL_ERROR when the connection is still good, if executed in an aborted transaction. (I have no idea why in the world a fatal error would be reported, when the connection is perfectly good and a rollback is all that's needed.) I need to be able to distinguish this situation from a real fatal error, and PQstatus() appears to be unreliable for this purpose. A "" query that returns PGRES_EMPTY_QUERY seems to be a good indicator that the connection is good, even within aborted transactions. Now I just need to know whether this is documented and guaranteed to work. Suggestions of alternative methods are welcome. ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
