On larger longer running queries (about 40 min) is when it gets the return value of undf

I have no idea if this is the case in your situation, but maybe the network connection gets cancelled by some appliance (load balancer or firewall) between your client and your server. A network sniffer like wireshark on the client side or the server log could maybe tell you for the long-running queries if there was an unexpected disconnection while the query was executing.

One approach for a workaround could be to partition up your statements into smaller statements that execute quicker, for example by looping over limited clauses like where id between 0 and 1000000 etc., but that way you might lose transaction safety.

Maybe the Oracle client library has a way to send keep-alive packets during query execution so that the network path remains open?

In reply to Re: sth->execute returns undef when successful by Corion
in thread sth->execute returns undef when successful by Anonymous Monk

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