On Wed, Jan 13, 2010 at 12:00 AM, Andreas Raab <andreas.raab at gmx.de> wrote:

> Mariano Martinez Peck wrote:
>
>> That's exatly what it is explained in the slides, even with sequence
>> diagrams.
>>
>> OpenDBX, when possible, uses asynchronous queries. This means that it just
>> calls a function to send the query, and then, it loops asking "is it ready?"
>>  until the query is done So, we have "little locks". The goods news is that
>> after asking, if there are other process in the queue, it should be
>> processed. With this way we process several queries "at the same time.".  Se
>> the method   DBXPlatform >> processNextResultSet: aConnection querySettings:
>> aQuerySettings
>>
>> where we do:     (code = OpenDBX resultTimeout) ifTrue: [ (Delay
>> forMilliseconds: (aQuerySettings timeout asMiliseconds)) wait  ].
>>           It is not the best solution, of course, but we are limited to
>> FFI implementation.
>>
>> I said "OpenDBX, when possible"  because it not depends only in OpenDBX
>> but also in the client library. Some support this and some doesn't. But I
>> think most engines support this. I know PostgreSQL does. BTW, which OS are
>> you deploying on ?
>>
>
> RHEL 5.3 + unixODBC + MySQL. BTW, it's not as if ODBC doesn't support
> asynchronous operations either (see for example
> http://msdn.microsoft.com/en-us/library/ms713563%28VS.85%29.aspx)


Thanks for the link. I wasn't aware of that. However, do you know which
function does the squeak ODBC driver calls ? because maybe there are
asynchronous  queries, but the driver is calling the synchronous ones.


> if the drivers support it. Unfortunately, I've found that "if the driver
> supports it" means mostly flipping a coin.
>
>
Yes, true. At least in OpenDBX it always tries to use them if possible.

I use to know (I asked OpenDBX developer) which backend and in which OS it
could be asynchronous, but I don't find it. Maybe I should ask again.

Cheers

Mariano


> Cheers,
>  - Andreas
>
>
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