Plack::Middleware::Debug::DBIC::QueryLog - DBIC Query Log and Query Analyzer


Adds a debug panel and querylog object for logging DBIx::Class queries. Has support for Catalyst via a Catalyst::TraitFor::Model::DBIC::Schema::QueryLog compatible trait, Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack.

    use Plack::Builder;

    my $app = ...; ## Build your Plack App

    builder {
      enable 'Debug', panels =>['DBIC::QueryLog'];

And in you Catalyst application, if you are also using Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack

    package MyApp::Web::Model::Schema;
    use Moose;
    extends 'Catalyst::Model::DBIC::Schema';

      schema_class => 'MyApp::Schema',
      traits => ['QueryLog::AdoptPlack'],
      ## .. rest of configuration


DBIx::Class::QueryLog is a tool in the DBIx::Class software ecosystem which benchmarks queries. It lets you log the SQL that DBIx::Class is generating, along with bind variables and timestamps. You can then pass the querylog object to an analyzer (such as DBIx::Class::QueryLog::Analyzer) to generate sorted statistics for all the queries between certain log points.

Query logging in Catalyst is supported for DBIx::Class via a trait for Catalyst::Model::DBIC::Schema called Catalyst::TraitFor::Model::DBIC::Schema::QueryLog. This trait will log all the SQL used by DBIx::Class for a given request cycle. This is very useful since it can help you identify troublesome or bottlenecking queries.

However, Catalyst::TraitFor::Model::DBIC::Schema::QueryLog does not provide out of the box outputting of your analyzed query logs. Usually you need to add a bit of templating work to the bottom of your webpage footer, or dump the output to the logs. We'd like to provide a lower ceremony experience.

Additionally, it would be nice if we could provide this functionality for all Plack based applications, not just Catalyst. Ideally we'd play nice with Plack::Middleware::Debug so that the table of our querylog would appear as a neat Plack based Debug panel. This bit of middleware provides that function.

Basically we create a new instance of DBIx::Class::QueryLog and place it into $env->{'plack.middleware.dbic.querylog'} (We use the underlying features in Plack::Middleware::DBIC::QueryLog) so that it is accessible by all applications running inside of Plack. You need to 'tell' your application's instance of DBIx::Class to use this $env key and make sure you set DBIx::Class's debug object correctly. The officially supported interface for this in via the supporting class Plack::Middleware::DBIC::QueryLog:

    use Plack::Middleware::DBIC::QueryLog;

    my $querylog = Plack::Middleware::DBIC::QueryLog->get_querylog_from_env($env);
    my $cloned_schema = $schema->clone;

In this example $env is a Plack environment, typically passed into your PSGI compliant application and $schema is an instance of DBIx::Class::Schema

We clone $schema to avoid associating the querylog with the global, persistant DBIC schema object.

Then you need to enable the Debug panel, as in the \SYNOPSIS. That way when you view the debug panel, we have SQL to review.

There's an application in '/example' you can review for help. However, if you are using Catalyst and a modern Catalyst::Model::DBIC::Schema you can use the trait Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack, which is compatible with Catalyst::TraitFor::Model::DBIC::Schema::QueryLog.

If you want a querylog but don't want or need the Plack debug panel, you should take a look at Plack::Middleware::DBIC::QueryLog.

See the "SYNOPSIS" example for more details.


This debug panel defines the following options.


This is the class which is used to build the querylog unless one is already defined. It defaults to DBIx::Class::QueryLog. You should probably leave this alone unless you need to subclass or augment DBIx::Class::QueryLog.

If the class name you pass has not already been included (via use or require) we will automatically try to require it.


Takes a HashRef which is passed to DBIx::Class::QueryLog at construction.


Plack::Middleware::Debug, Catalyst::TraitFor::Model::DBIC::Schema::QueryLog, Catalyst::Model::DBIC::Schema, Catalyst::TraitFor::Model::DBIC::Schema::QueryLog::AdoptPlack


John Napiorkowski, <>


Copyright 2011 John Napiorkowski

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.