On Feb 8, 2008 12:53 AM, Willy-Bas Loos <willybas@xxxxxxxxx> wrote:
Hi,
We have a large set of simple queries, that can run in both PostgreSQL and BDE (Corel Paradox backend).
We want to be able to re-create some half-product tables (cache, sortof), while they are (possibly) being accessed by other users. Otherwise there would be a severe performance penalty. We were thinking about re-creating them in a transaction. Concurrent transactions may occur.
But it doesn´t seem to work out.
I tested it this way (in PostgreSQL 8.2.6 and in 8.1.10):
in TTY1, run:
create table test (id int4 primary key);
insert into test (id) values (1);
then in TTY2, run
begin;
drop table test;
create table test (id int4 primary key);
insert into test (id) values (2);
then, in TTY1:
select * from test;
Actually, i thought of a longer test, but it stops here - there is no response, no prompt anaymore, until i cancel the query.
Is this correct behaviour of PostgreSQL? (i think not..)
The easiest solution would be to just empty the tables instead of dropping them i guess, but this made me wonder about transactions. I've read the chapter on Transaction Isolation, but it doesn't explain the behaviour of DROP. Anything else i need to know? (OMG transactions are not pure magic ;P )
WBL
