Is there an easy way to override DBI::prepare or 'execute' in such a way that I can add some logging to give a stack trace (Carp::cluck) showing where every database query in a large body of code was called from, as it runs?
Assuming that you control the code that's doing the prepare(), a simple approach is to wrap the object that prepare() hands back. Something like:
my $sth = $dbh->prepare("SELECT ... WHERE ... ? ...");
$sth = Statement->wrap($sth, "Label");
...
$sth->execute(@args);
The wrapping class looks something like:
package Statement;
sub wrap {
my($pkg, $sth, $label) = @_;
bless [ $sth, $label ], $pkg;
}
sub execute {
my $self = shift;
# tracing, timing code here. E.g.,
log($self->[1] . " is about to execute");
my $rv = $self->[0]->execute(@args);
# timing, logging code here
}
sub finish {
my $self = shift;
$self->[0]->finish();
}
1;
You'll probably find that you need to wrap some additional methods.
The label helps track the statement and makes the logs more readable, and could include the text of the query.
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