Warren Young wrote:
> Drew M. wrote:
>> The other code in query.h uses an overloaded << operator with a Query
>> on the left side. Your code uses an ostringstream, which is why the
>> is different.
> Yes. We may not want to bother creating MaxPacketPolicy for this
> first version. It may be too difficult to implement to justify the
> small safety it provides over the easier to implement
> SizeThresholdPolicy. The latter doesn't need a separate stream object;
> you can insert the data straight into *this, as Query::insert() does.
Can you explain why this is so? I don't understand why using << with
the Query object quotes the data values as needed but << with a
different kind of stream doesn't. I must have missed something because
I don't see what makes a difference.
> I understand your worry, but keep in mind,
> Query::insertfrom(container, policy) will need to make several queries
> to insert a large container. If any one of them fails, do you really
> want to leave half of the container's data still in the DB?
> Query::insert() either succeeds or fails; it never inserts half a
> record. I think Query::insertfrom() should behave the same way, at
> least by default.
> Perhaps each policy class should have an optional "no transactions"
> boolean parameter on its ctor, defaulting to true.
Good point. The DefaultInsertPolicy certainly doesn't need transactions
no matter what since it always creates a single query.
> Also keep in mind that BEGIN, COMMIT and ROLLBACK are no-ops on MySQL
> when the underlying DB engine doesn't support transactions.