Developers of Sympa

[Guillaume Rousse <address@concealed>]

Le 25/07/2013 19:25, IKEDA Soji a écrit :
> On Thu, 25 Jul 2013 17:21:11 +0200
> David Verdin <address@concealed> wrote:
>
> > Le 25/07/13 16:49, Guillaume Rousse a écrit :
> > > Everything related to parameter binding in do_query and
> > > do_prepared_query can be discarded, those methods don't exist anymore,
> > > and binding is now delegated to DBI internals.
> > As we speak about it: why not keeping a single function to do all the
> > query business?
> > We always do the same succession of calls to do a query to database. I
> > refactored all them in do_query and even planned to cover the final mile
> > by fetching data in this sub and sending the hashref or arrayref we
> > needed actually in the code.
>
> I wonder whether non-binding version of do_query() may be discarded
> or not.
>
> - Statement cache (either implemented in DB engine or emulated by DBI)
>    will be cleaned unexpectedly earlier, if queries by users for each
>    are prepared.
What is cached is the unbinded query handle ("SELECT * FROM table WHERE 
id = ?"), resulting from prepare() call.

I removed all calls to $handle->terminate(), excepted in Sympa::Database 
DESTROY method.

All usage of query handle to read returned values immediatly follows a 
call to $handle->execute(), where final values binding actually occurs.

I don't see any scenario where a query handle resulting from 
get_query_handle() would be cleaned (terminated ?), or used in an 
erroneous state. As long as we are in a non-threaded application, of course.

> - Before any expressive ORM is integrated into Sympa, do_query()
>    function to execute raw SQL seems to be required.
I'm not sure about what you cal 'raw SQL'. Both execute_query() and 
get_query_handle() takes an SQL string as main argument.

Constructing this SQL string is still the responsability of calling 
code. But whereas you previously inserted '%s' placeholders, and 
transmitted quoted values to do_query() function, now you insert '?' as 
placeholder, and you either pass values to bind to execute_query(), 
either you perform binding through $handle->execute() directly.

# SELECT query
my $query = "SELECT * FROM table WHERE id = ?";
my $handle = $database->get_query_handle($query);
$handle->execute($id);
while (my @row = $handle->fetchrow()) {
   ....
}

# non-SELECT query
my $query = "DELETE FROM table WHERE id = ?";
my $rows = $database->execute_query($query, $id);

--
Guillaume Rousse
INRIA, Direction des systèmes d'information
Domaine de Voluceau
Rocquencourt - BP 105
78153 Le Chesnay
Tel: 01 39 63 58 31

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