Thanks Dean.
Tim.
On Mon, Jan 22, 2007 at 10:51:00AM -0800, Dean Arnold wrote:
> Tim Bunce wrote:
> >On Fri, Sep 22, 2006 at 05:40:53PM -0700, Dean Arnold wrote:
> >>Just so I'm clear:
> >>
> >>"DBI's default execute_array()/execute_for_fetch() requires the use of
> >>positional (i.e., '?') placeholders. Drivers which B<require> named
> >>placeholders must implement their own execute_array()/execute_for_fetch()
> >>methods to properly sequence bound parameter arrays."
> >
> >"... or they can emulate positional placeholders (DBD::Oracle does this)".
> >
> >I'd guess that emulating positional placeholders would be both simpler
> >and more useful for general script portability.
> >
> >>>Could you update the docs? (If you don't have write access to the dbi
> >>>repository yet, send me your auth.perl.org username and I'll give it to
> >>>you.)
>
> Time to get this out of my TODO queue...
>
> I noticed that DBI::DBD was silent on the whole area of
> array binding, so here's what I've added.
>
> - Dean
>
> =head4 The execute_array(), execute_for_fetch() and bind_param_array()
> methods
>
> In general, DBD's only need to implement C<execute_for_fetch()> and
> C<bind_param_array>. DBI's default C<execute_array()> will invoke the
> DBD's C<execute_for_fetch()> as needed.
>
> The following sequence describes the interaction between
> DBI C<execute_array> and a DBD's C<execute_for_fetch>:
>
> =over
>
> =item 1
>
> App calls C<$sth-E<gt>execute_array(\%attrs, @array_of_arrays)>
>
> =item 2
>
> If C<@array_of_arrays> was specified, DBI processes C<@array_of_arrays> by
> calling
> DBD's C<bind_param_array()>. Alternately, App may have directly called
> C<bind_param_array()>
>
> =item 3
>
> DBD validates and binds each array
>
> =item 4
>
> DBI retrieves the validated param arrays from DBD's ParamArray attribute
>
> =item 5
>
> DBI calls DBD's C<execute_for_fetch($fetch_tuple_sub, [EMAIL PROTECTED])>,
> where C<&$fetch_tuple_sub> is a closure to iterate over the
> returned ParamArray values, and C<[EMAIL PROTECTED]> is an array to receive
> the disposition status of each tuple.
>
> =item 6
>
> DBD iteratively calls C<&$fetch_tuple_sub> to retrieve parameter tuples
> to be added to its bulk database operation/request.
>
> =item 7
>
> when DBD reaches the limit of tuples it can handle in a single database
> operation/request, or the C<&$fetch_tuple_sub> indicates no more
> tuples by returning undef, the DBD executes the bulk operation, and
> reports the disposition of each tuple in [EMAIL PROTECTED]
>
> =item 8
>
> DBD repeats steps 6 and 7 until all tuples are processed.
>
> =back
>
> E.g., here's the essence of L<DBD::Oracle>'s execute_for_fetch:
>
> while (1) {
> my @tuple_batch;
> for (my $i = 0; $i < $batch_size; $i++) {
> push @tuple_batch, [ @{$fetch_tuple_sub->() || last} ];
> }
> last unless @tuple_batch;
> my $res = ora_execute_array($sth, [EMAIL PROTECTED],
> scalar(@tuple_batch), $tuple_batch_status);
> push @$tuple_status, @$tuple_batch_status;
> }
>
> Note that DBI's default execute_array()/execute_for_fetch() implementation
> requires the use of positional (i.e., '?') placeholders. Drivers
> which B<require> named placeholders must either emulate positional
> placeholders (e.g., see L<DBD::Oracle>), or must implement their own
> execute_array()/execute_for_fetch() methods to properly sequence bound
> parameter arrays.
>
>
>
