When does PQstatus() update?
Hi,
Just wondering when the result of the function PQstatus() gets updated?
Can I expect it to be updated while connected even without performing any
transactions/communications with the backend?
I tried PQexec()'ing a "BEGIN TRANSACTION" on a dead backend and
immediately checked PQstatus() as well as PQresultStatus(). PQstatus()
returned a CONNECTION_OK while PQresultStatus() returned
PGRES_FATAL_ERROR. I tried it again on the same dead-connection backend a
couple of seconds later and got a CONNECTION_BAD fro PQstatus() and a
PGRES_NONFATAL_ERROR from PQresultStatus().
L L Richi Plana 8^) ,-,-. ,-,-. ,-,-. ,-,-. ,-
LL LL Systems Administrator / / \ \ / / \ \ / / \ \ / / \ \ / /
LLLLL Mosaic Communications, Inc. \ \ / / \ \ / / \ \ / / \ \ / /
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Hi,
I have some trouble with subselects. (Version 6.3).
If I try
Select name, address from costumers where cod_costumer in (
Select cod_costumer from logins where total_usage > 0);
It take lots of time (really I din't wait till the end).
But if I manualy split in
Select cod_costumer from logins where total_usage > 0;
getting
( 1, 9, 15, 18 , 40)
and then use
Select name, address from costumers where cod_costumer in ( 1, 9,
15, 18 , 40);
All is OK.
Is this type of subselect suported ?
Thanks
Giovanni Floridia
Hi,
I have some trouble with subselects. (Version 6.3).
If I try
Select name, address from costumers where cod_costumer in (
Select cod_costumer from logins where total_usage > 0);It take lots of time (really I din't wait till the end).
But if I manualy split in
Select cod_costumer from logins where total_usage > 0;
getting
( 1, 9, 15, 18 , 40)
and then use
Select name, address from costumers where cod_costumer in ( 1, 9,
15, 18 , 40);All is OK.
Is this type of subselect suported ?
Thanks
Giovanni Floridia
Yes it's supported, but the subselect will be executed for each row of
the main select.
This should be a faster select (but not as fast as your second one).
Select name, address from costumers where EXISTS(Select 1 from logins
where total_usage > 0 AND logins.cod_customer = customers.cod_customer);
-DEJ
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