On Fri, May 03, 2002 at 10:24:07AM +0100, Simon Oliver wrote: > Tim Bunce wrote: > > > > 4/ Add the ability to fetch a subset of rows in a single call. > > I'm thinking in terms of adding a parameter to fetchall_arrayref > > to request that only N rows be fetched. > > I use a GetRows function for this purpose - it's basically a copy of the > selectall_arrayref/fetchall_arrayref code, with added $top parameter - > syntax is: > > $ary_ref = GetRows($dbh, $stmt, $top, \%attr, @bind) > > $dbh a database handle > $stmt a prepared statement handle or SQL statement > $top a possitive integer to limit the number of rows returned > \%attr a hash reference to pass driver specific hints > @bind a list of bind parameters > > If $top <1 it returns all rows > > If $top > 0, $sth->finish is called before the function returns. > > Recently I have considered changing the spec so that $sth->finish is not > called automatically in order to facilitate retrieving more $top rows from > $sth later. However, this leads to a problem whereby, if $stmt is a SQL > statment (requiring the funtion to create a temporary statement handle), > if $sth->finish is not called before returning from the function but there > are rows left in the query an error will occur as the function returns and > the statement handle is detroyed. This can be solved by only calling > $sth->finish if $top > 1 and !ref($stmt), but this would nead to be > clearly documented. (Did that make any sense?)
Yeap, that's the plan. > > I'm also thinking of adding > > a parameter to pass in a reference to any array onto which you'd > > like the new rows pushed. > That would also be useful. > > But how would you implement these changes without compromising backward > compatibility? Firstly I doubt that many (or even any) drivers have implemented their own fetchall_arrayref method. Most (all) would simply use the DBI's one. Secondly the attribute to specify the max rows can be specified as being a hint that some old drivers might ignore. Same goes for passing in the array ref to push rows onto. Tim.
