Slow write to sqlite on usb sticks

[Peter Haworth]

Once again, this varies form db to db.  Even sqlite3 can now allow readers
while the db is locked by setting the Write Ahead Locking pragma.

For mySQL, there is a LOCK and an UNLOCK command which allow you to lock
individual tables for read and/or write access, as well as BEGIN and END,
which lock the whole database.  There's a discussion on how LOCK/UNLOCK and
BEGIN/END work here<http://dev.mysql.com/doc/refman/5.5/en/lock-tables-and-transactions.html>
but
I'd be inclined to use LOCK and UNLOCK rather than BEGIN/END for more
granularity unless you are carrying out some admin task for which you need
exclusive access to the whole db.

I don't know anything about locking on other SQL implementations (yet!).

Pete
lcSQL Software <http://www.lcsql.com>



On Thu, Apr 26, 2012 at 3:22 PM, Bob Sneidar <bobs at twft.com> wrote:

> Oh thanks. I was aware that beginning a transaction made the database
> writable by only the client who began the transaction, but does it lock
> people out of reads as well? In the past I would manually lock a database
> while inserting records or before doing a transactional update, so that I
> could mark a particular master record as read only. I would then unlock the
> database and update as necessary to minimize the impact on other users. I
> did this only because that was what an old app called SBT written in Foxpro
> used to do, and that was all I knew at the time, but with transactions,
> maybe I don't need to worry about that anymore.
>
> Bob
>
>
> On Apr 26, 2012, at 3:14 PM, Peter Haworth wrote:
>
> > I think you're using mySQL Bob?  If so, be aware that BEGIN and END are
> > also the means by which you lock the database.  Doesn't matter too much
> > with sqlite because it's basically a single user db but with multi user
> dbs
> > like mySQL (actually just about any db other than sqlite), locking is a
> > whole other story!
> >
> > Pete
> > lcSQL Software <http://www.lcsql.com>
> >
> >
> >
> > On Thu, Apr 26, 2012 at 2:58 PM, Bob Sneidar <bobs at twft.com> wrote:
> >
> >> Yes, transactions... good! I need to incorporate them into my app when I
> >> am ready to go into production (as if I will ever get to that point!).
> >>
> >> Bob
> >>
> >>
> >> On Apr 26, 2012, at 2:38 PM, Terry Judd wrote:
> >>
> >>> Wow, thanks Pete - I'll definitely give this method a try.
> >>>
> >>> Terry..
> >>
> >>
> >> _______________________________________________
> >> use-livecode mailing list
> >> use-livecode at lists.runrev.com
> >> Please visit this url to subscribe, unsubscribe and manage your
> >> subscription preferences:
> >> http://lists.runrev.com/mailman/listinfo/use-livecode
> >>
> > _______________________________________________
> > use-livecode mailing list
> > use-livecode at lists.runrev.com
> > Please visit this url to subscribe, unsubscribe and manage your
> subscription preferences:
> > http://lists.runrev.com/mailman/listinfo/use-livecode
>
>
> _______________________________________________
> use-livecode mailing list
> use-livecode at lists.runrev.com
> Please visit this url to subscribe, unsubscribe and manage your
> subscription preferences:
> http://lists.runrev.com/mailman/listinfo/use-livecode
>