Slow write to sqlite on usb sticks

[Bob Sneidar]

Thanks Pete very informative. I will have a look at that link today. 

Bob


On Apr 26, 2012, at 4:36 PM, Peter Haworth wrote:

> 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..
>>>> 
>>>> 
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