[Koha-devel] Avoid $sth->finish

[Joe Atzberger]

Kohackers --

I want to mention this because I've seen a lot of recent patches still using
the old style of code calling $sth->finish() explicitly.  I know a lot of
the codebase still does this internally, but for Koha such usage is almost
always wrong.

If this were just my personal contention, I would couch this in terms of an
RFC to deprecate the usage.  But we don't get a choice here: DBI is telling
us "don't do it".

Please refer to the DBI
perldoc<http://search.cpan.org/%7Etimb/DBI-1.608/DBI.pm#finish>
:

The finish method is rarely needed, and frequently overused, but can
sometimes be helpful in a few very specific situations to allow the server
to free up resources (such as sort buffers).

When all the data has been fetched from a SELECT statement, the driver
should automatically call finish for you. So you should *not* normally need
to call it explicitly *except* when you know that you've not fetched all the
data from a statement handle. The most common example is when you only want
to fetch one row, but in that case the selectrow_* methods are usually
better anyway. *Adding calls to finish after each fetch loop is a common
mistake, don't do it, it can mask genuine problems like uncaught fetch
errors.*
That last sentence is the most concrete and important (hence my bolding).
Moral of the story: don't do it.  Or if you think you have to, at least
comment why, like:
$sth->finish();  # FIXME: leaving data unfetched, should rework query

-- 
Joe Atzberger
LibLime - Open Source Library Solutions
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