On Tue, Dec 21, 2010 at 3:07 PM, Daniel Verite <daniel@manitou-mail.org> wrote:
> Kelly Burkhart wrote:
>
>> #define COMMANDS "select current_timestamp; select pg_sleep(5); select
>> current_timestamp"
>
> You should use current_clock() instead of current_timestamp, because
> current_timestamp returns a fixed value throughout a transaction.
Well, that's correct, but irrelevant -- Kelly's analysis is correct.
The documentation for PQgetResult states:
"Using PQsendQuery and PQgetResult solves one of PQexec's problems: If
a command string contains multiple SQL commands, the results of those
commands can be obtained individually. (This allows a simple form of
overlapped processing, by the way: the client can be handling the
results of one command while the server is still working on later
queries in the same command string.) However, calling PQgetResult will
still cause the client to block until the server completes the next
SQL command. This can be avoided by proper use of two more functions:"
but control is not returned until all three queries have resolved.
this is probably an issue with libpq. investigating...
merlin
