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Postings from February 2011
On 01/02/2011 20:50, Tim Bunce wrote:
> On Tue, Feb 01, 2011 at 10:58:14AM -0500, John Scoles wrote:
>> On 01/02/2011 10:48 AM, Tim Bunce wrote:
>>> On Mon, Jan 31, 2011 at 08:39:40PM +0000, Martin J. Evans wrote:
>>>> I imagine most DBDs [if not all] that implement execute_array
>>> [Just a reminder that drivers can opt to implement just
>>> execute_for_fetch() and use the DBI's default execute_array() method,
>>> which then calls execute_for_fetch().]
>>>
>>>> themselves) the rows affected will be -1 per execute (as the driver
>>>> does not know affected rows) and so I'd expect $rows to be -1 and
>>>> not 18. DBI gets away with this as it does an execute for each row
>> The thing is OCI will know the end result of rows effected I just
>> does not know the #rows for each statement.
>>
>> So on an update with say 4 tuples and 6 rows updates the tupels
>> would look like this
>>
>> -1
>> -1
>> -1
>> -1
>> wile the list context one would get
>> Tuples=4
>> rows =6
> I think we could factor into the spec the fact that some drivers can
> return an overall row count but not per-tuple counts.
>
Did that a few hours ago but not committed yet.
>> My only concern is when it does error (no matter what the setting of
>> AutoCommit) you always get unef;
> Umm, yes. Returning undef (or an empty list) if there was any kind of
> error causes useful information (the total row count) to be discarded.
>
I don't see why when called in list context. Just because execute_array
partially succeeded (or failured) only means undef needs to be returned
for the first scalar and does not affect the rows affected.
> This brings us back to the question of whether a failure of a single
> tuple should cause execute_array() itself to return an error.
>
> ODBC doesn't do that. It treats that situation as SUCCESS_WITH_INFO
> and that does seem very reasonable.
>
The funny thing is being an big user of ODBC, I don't (and others in
this thread expressed the same belief). For me, if I use execute_array
(with AutoCommit on or not) my principle issue is I want to know if
anything failed so I do:
$dbh->{RaiseError} = 1;
my $ret = eval {
execute_array(...)
};
do_something_on_error() if ($@ || !$ret); # amended for DBD::Oracle behavior
NOTE: I've only started doing this since realising DBD::Oracle does not
raise an error.
Why put the onus on people who cannot accept some tuples to fail to
check the ArrayTupleStatus instead of put it on those who can accept
some to fail to examine ArrayTupleStatus? My feeling is that it is very
serious to ignore a partial failure and so the default should be to
ensure you know about it with RaiseError. For those people who can
accept a tuple to fail, they can look at ArrayTupleStatus and still
commit the changes.
>> but I can live with that.
> Perhaps we could default to the SUCCESS_WITH_INFO model and add an
> attribute for people to use if they want tutple errors to cause
> execute_array() itself to return an error.
>
> We can debate the name later, but for now let's call it:
>
> ArrayPromoteTupleError => 1
>
> Tim.
which defaults to 1, I hope.
Incidentally, I just blogged about this a few hours ago as I think it is
a serious problem to ignore potential failures. Add that to the fact
that some versions of Oracle database (broken) return success with info
but don't then commit the ok tuples.
Martin
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