> So why do you need it or do you need to learn more about versioning?

How I came to ask this question:
Let's say my table is full of conference room reservations, each
record having a starttime timestamp and duration (or endtime timestamp)
Now if I let out a room I have to check if the requested time period
conflicts with any records in the table (20:00->21:30 conflicts with
21:00->22:00)
And only after this check can I insert the record
(these two steps are done by a SP)
So what I need is that nobody should be able to update the table AFTER
the SP checks for conflicting records

Now this can be accomplished with the SET TRANSACTION method, but if I
really have to compare it to locks:
"SET TRANSACTION starts a transaction" [langref.pdf,153. page]
This means I cannot set transaction in a SP, which would be
appropriate (I need the lock because of the way the SP works, not
because of the client...). This is especially ugly, because for
performance reasons I am going to use the RESERVING table1,table2
parameter (with SNAPSHOT isolation), which means I have to specify the
table names in my java client (and all this because of how the SP
works, all I'd want to do is call the SP with a few arguments, let the
SP handle the metadata). Pray tell me if I'm missing something.

And to answer Ann's question:
You can use the LOCK statement anywhere in a transaction, evidently in
a SP too
(I must add I haven't tried Postgre because I'm a firebird fan, and am
also needing it as a win service (Postgre is still in RC), but I've
been reading a lot of documentation today :) )

Regards,
John

>
> nagypapi wrote:
>
> >I was wondering, are there any plans to implement explicit table
> >locking as is in PostgreSQL:
> >http://www.postgresql.org/docs/7.4/interactive/explicit-locking.html
> >http://www.postgresql.org/docs/7.4/interactive/sql-lock.html
> >
> >This topic was more or less previously discussed in firebird-java, and
> >we got to the conclusion that setting the transaction isolation level
> >is a possible solution, but explicit locking seems more appropriate
> >and flexible (from a java programmer's point of view)
> >John
> >
> >
> >
> >
> >
> >
> >Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
> --
> Thomas Miller
> Wash DC Delphi SIG Chairperson
> Delphi Client/Server Certified Developer
> BSS Accounting & Distribution Software
> BSS Enterprise Accounting FrameWork
>
> http://www.bss-software.com
> http://www.cpcug.org/user/delphi/index.html
> https://sourceforge.net/projects/uopl/
> http://sourceforge.net/projects/dbexpressplus