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Re: Cancelling Requests Frontend/Backend Protocol TCP/IP

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On 02/11/2009, at 17:35, Tom Lane wrote:

Raimon Fernandez <coder@xxxxxxxxx> writes:
Quoted from the documentation:
"The cancellation signal might or might not have any effect — for
example, if it arrives after the
backend has finished processing the query, then it will have no
effect.

Here I understand that maybe it will have NO effect, so postgresql
will still sending rows and rows and rows ...

If you're too late, the backend has already sent all the rows. There's not much we can do about data that's already in flight. There probably
won't be that much of it though, as TCP stacks don't buffer infinite
amounts of data.

The sentence 'backend has finished processing the query' means that postgresql has finished processing the select and also has sent all the rows ?

I thought it meant only processing the request, and the rows were not yet sent all of them.

If the rows have been sent, and there are data in the TCP buffer, that's another story ...

thanks,

raimon

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