Question Re: Would a tcp/ip client recognize if a commit is lost in Technology Q&A

Would a tcp/ip client recognize if a commit is lost

MCMartin — Mon, 13 Feb 2012 13:06:06 GMT

Would a database client using tcp/ip recognize if the packet transmitting the commit command to the server is lost?

Re: Would a tcp/ip client recognize if a commit is lost

Breck_Carter — Mon, 13 Feb 2012 15:00:43 GMT

Probably not, because TCP provides packet recovery: http://en.wikipedia.org/wiki/Packet_loss#Packet_recovery

Re: Would a tcp/ip client recognize if a commit is lost

MCMartin — Tue, 14 Feb 2012 02:57:02 GMT

So, there is no hand-shake on database level?

Re: Would a tcp/ip client recognize if a commit is lost

Former Member — Tue, 14 Feb 2012 03:53:12 GMT

If commit is succesful than you get succesfull return code. If tcp connection is broken while you transmit packet with commit than you get connection error (tcp garanee it). But may be will be interesting for you distributed transaction/two phase commit technology?

Re: Would a tcp/ip client recognize if a commit is lost

MCMartin — Tue, 14 Feb 2012 04:48:18 GMT

I am wondering if a situation is possible there the client sends the commit but server never receives it and client waits indefinetly to receive the handshake.

Re: Would a tcp/ip client recognize if a commit is lost

VolkerBarth — Tue, 14 Feb 2012 05:03:33 GMT

The possible answers are wayyy beyond my network knowledge, but the effect of the LivenessTimeout would come into play here, methinks.

Re: Would a tcp/ip client recognize if a commit is lost

Former Member — Tue, 14 Feb 2012 18:22:04 GMT

It won't recognize this particular failure, because TCP will provide packet recovery as Breck has mentioned. Assuming TCP isn't able to recover and resend the packet, the client libraries should return a communication error (-85):

Communication error

Other failures for a commit should also be surfaced as an error. Ultimately, if the call making a commit returns without an error code, the commit should succeed.