Nuno Lucas wrote:
> On Wed, Jun 3, 2009 at 11:22 PM, Nikolaus Rath <[email protected]> wrote:
>
>> Nuno Lucas <[email protected]> writes:
>>
>>> On Wed, Jun 3, 2009 at 2:41 AM, Nikolaus Rath <[email protected]> wrote:
>>>
>>>> Nuno Lucas <[email protected]> writes:
>>>>
>>>>> On Tue, May 26, 2009 at 5:17 PM, Nikolaus Rath <[email protected]> wrote:
>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> How can I determine the rowid of the last insert if I am accessing the
>>>>>> db from different threads? If I understand correctly,
>>>>>> last_insert_rowid() won't work reliably in this case.
>>>>>>
>>>>> It should work if you do:
>>>>>
>>>>> BEGIN
>>>>> INSERT ...
>>>>> last_insert_rowid()
>>>>> END
>>>>>
>>>> That would be very nice. But does "it should work" mean that you know
>>>> that it works (and it is documented and guaranteed)? The above sounds a
>>>> bit uncertain to me...
>>>>
>>> It just means I'm too old to assume anything is certain. The Universe
>>> is always conspiring against you ;-)
>>>
>>> What I mean is that if it doesn't work, then you found a bug, most
>>> probably in your own code.
>>>
>> Well, now you are in direct contradiction to Igor who says that it does
>> not work:
>>
>
> Let's try end this confusion...
>
> If you open a sqlite shell and do:
>
> SQLite version 3.6.14.2
> Enter ".help" for instructions
> Enter SQL statements terminated with a ";"
> sqlite> begin;
> sqlite> begin;
Since we are discussing threads here, the example is meaningless.
"begin" is a piece of text which is parsed into opcodes and then
processed by a complied virtual machine. Threads switch at the machine
code level, so a thread could switch between the processing of the 'g'
and the 'i' of the first 'begin'.
IMHO, if you are programming in threads, maintain control in the
application. Threads are already non-deterministic and potentially
buggy. The last thing one wants is to add places of uncertainty.
Pseudocode:
entryPoint
grabMutex
db.execute('begin;')
db.execute('insert...
lastInsertRowId = db.last_insert_rowid
releaseMutex
Anything else "might" work, but I wouldn't want to waste time losing
sleep over it.
FWIW
John
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