Re: [sqlite] Is there a command to lock a database for a short while (0.25 sec, say)

[James K. Lowden]

On Wed, 17 Apr 2013 15:39:50 +0200
"J Trahair"  wrote:

> I'm looking for a way to ensure other users aren't allowed to write
> to the database during this quarter-second period.

That might work for you this time, but it doesn't scale well;
historically that's why the DBMS took over locking.  

You might instead want to consider a more relational approach.  For
example, you could have a "current version" table somewhere with one
row.  Various tables would have "version" columns.  The application
could select from views that join to the current-version table.  

Your update could add rows with a new version, update the
current-version row, and at its leisure delete rows for the prior
version.  Because the update is atomic, the transition is
instantaneous; no one is ever blocked but for an instant.  

Of course I don't know specifically what you're trying to do.  I'm just
saying that lock-the-world isn't a general solution, and the DBMS
supports many general alternatives.  

--jkl
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] Is there a command to lock a database for a short while (0.25 sec, say)

[Stephen Chrzanowski]

Don't forget that your "other" applications will need to extend their
connection time outs, otherwise, while "this" application has the lock, the
"other" applications will time out and throw errors.


On Wed, Apr 17, 2013 at 9:43 AM, Simon Davies
wrote:

> On 17 April 2013 14:39, J Trahair  wrote:
> > Hi everyone
> >
> > Can my application lock the database for its own exclusive use at the
> beginning of a series of INSERTs UPDATEs and SELECTs, then unlock it again
> afterwards? I've read about the five locking states (unlocked, shared,
> etc.) but I assume the dll handles all that at INSERT or UPDATE time. I'm
> looking for a way to ensure other users aren't allowed to write to the
> database during this quarter-second period.
>
> http://www.sqlite.org/lang_transaction.html
> BEGIN EXCLUSIVE
>
> >
> > Thanks in advance.
> >
> > Jonathan Trahair
>
> Regards,
> Simon
> ___
> sqlite-users mailing list
> sqlite-users@sqlite.org
> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
>
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

Re: [sqlite] Is there a command to lock a database for a short while (0.25 sec, say)

[Simon Davies]

On 17 April 2013 14:39, J Trahair  wrote:
> Hi everyone
>
> Can my application lock the database for its own exclusive use at the 
> beginning of a series of INSERTs UPDATEs and SELECTs, then unlock it again 
> afterwards? I've read about the five locking states (unlocked, shared, etc.) 
> but I assume the dll handles all that at INSERT or UPDATE time. I'm looking 
> for a way to ensure other users aren't allowed to write to the database 
> during this quarter-second period.

http://www.sqlite.org/lang_transaction.html
BEGIN EXCLUSIVE

>
> Thanks in advance.
>
> Jonathan Trahair

Regards,
Simon
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

[sqlite] Is there a command to lock a database for a short while (0.25 sec, say)

[J Trahair]

Hi everyone

Can my application lock the database for its own exclusive use at the beginning 
of a series of INSERTs UPDATEs and SELECTs, then unlock it again afterwards? 
I've read about the five locking states (unlocked, shared, etc.) but I assume 
the dll handles all that at INSERT or UPDATE time. I'm looking for a way to 
ensure other users aren't allowed to write to the database during this 
quarter-second period.

Thanks in advance.

Jonathan Trahair
___
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users