[Lazarus] What is a TSQLTransaction and why do I need one?

[michael.vancanneyt at wisa.be]

On Mon, 29 Nov 2010, Joost van der Sluis wrote:

> On Wed, 2010-11-24 at 20:57 +0100, Michael Van Canneyt wrote:
>>
>> On Wed, 24 Nov 2010, Alexsander Rosa wrote:
>>
>>> But it is transparent to the libpq programmer; why it's not transparent with sqldb?
>>
>> Correction: it can be transparant in libpq.
>>
>> But we can make it so in SQLDB.
>>
>> The SQLDB model is in fact modeled after Firebird.
>> Firebird offers more control over the transactions.
>>
>> We did not want to take away this possibility, so we modeled sqldb on
>> the most powerful RDBMS. This adds some overhead for the others.
>>
>> What we neglected to do is add what Martin added: offer a less intrusive
>> way for the programmer to use it (i.e. create a default transaction in the
>> background if none is specified, and close the transaction once the data
>> is read).
>>
>> But we'll do that too, all in good time.
>>
>> If someone is in a hurry, patches are definitely accepted.
>
> Problem is that I haven't found a good model for this. Martin's solution
> could be an idea, though.
>
> It could help if someone could sketch the typical wanted behavior from
> the transactions.

I sent an idea for an implementation in a reply to Alexsander Rosa.
basically:

TConnectionOption = (coAutoTransaction)
TConnectionOptions = set of TConnectionOption;

Property TSQLConnection.options = TConnectionOptions;

Procedure TSQLConnection.CreateDefaultTransaction;

If coAutoTransaction is set, and TSQLQuery does not have a TSQLTransaction
assigned, it creates one through TSQLConnection.CreateDefaultTransaction.
(It should be of type TSQLAutoTransaction, a simple descendent of
TSQLtransaction, so detection of 'default transaction' is simple)

Whenever a TSQLQuery statement is executed and the transaction of TSQLTransaction is
of type TSQLAutoTransaction, then it automatically commits (more flags can be introduced
for this).

Michael.