All -
I think I have a solution to the TODO tests in t/98rows_prefetch.t
and I think this may solve other issues, as well.
The problem: Non-data aspects to the query (such as rows) are
affecting the pull of prefetch'ed data.
The solution: Put the main query in a subquery. So, if we had
$foo_rs->search({
col1 => 3
}, {
rows => 2
prefetch => 'bar',
});
That currently translates (in MySQL) to "SELECT me.*, bar.* FROM
foo me JOIN bar USING (...) WHERE me.col1 = 3 LIMIT 2". If there are 3
rows in bar to each row in foo, we still only get the first two rows.
The query -should- be "SELECT me.*, bar.* FROM ( SELECT me.* FROM foo
me WHERE col1 = 3 LIMIT 2 ) me JOIN bar USING (...)". That way, the
limit is against the main query and the prefetch happens outside it.
Thus, the right number of rows are pulled back.
I think that transformation will work for all prefetches and I'm
working on applying that fix in the prefetch branch. Does anyone see
anything wrong with that?
Rob
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