DBIx::Class::Manual::Troubleshooting(3pm)		User Contributed Perl Documentation		 DBIx::Class::Manual::Troubleshooting(3pm)

NAME

       DBIx::Class::Manual::Troubleshooting - Got a problem? Shoot it.

   "Can't locate storage blabla"
       You're trying to make a query on a non-connected schema. Make sure you got the current resultset from $schema->resultset('Artist') on a
       schema object you got back from connect().

   Tracing SQL
       The "DBIC_TRACE" environment variable controls SQL tracing, so to see what is happening try

	 export DBIC_TRACE=1

       Alternatively use the "storage->debug" class method:-

	 $schema->storage->debug(1);

       To send the output somewhere else set debugfh:-

	 $schema->storage->debugfh(IO::File->new('/tmp/trace.out', 'w');

       Alternatively you can do this with the environment variable, too:-

	 export DBIC_TRACE="1=/tmp/trace.out"

   Can't locate method result_source_instance
       For some reason the table class in question didn't load fully, so the ResultSource object for it hasn't been created. Debug this class in
       isolation, then try loading the full schema again.

   Can't get last insert ID under Postgres with serial primary keys
       Older DBI and DBD::Pg versions do not handle "last_insert_id" correctly, causing code that uses auto-incrementing primary key columns to
       fail with a message such as:

	 Can't get last insert id at /.../DBIx/Class/Row.pm line 95

       In particular the RHEL 4 and FC3 Linux distributions both ship with combinations of DBI and DBD::Pg modules that do not work correctly.

       DBI version 1.50 and DBD::Pg 1.43 are known to work.

   Can't locate object method "source_name" via package
       There's likely a syntax error in the table class referred to elsewhere in this error message.  In particular make sure that the package
       declaration is correct. For example, for a schema " MySchema " you need to specify a fully qualified namespace: " package
       MySchema::MyTable; ".

   syntax error at or near "<something>" ...
       This can happen if you have a relation whose name is a word reserved by your database, e.g. "user":

	 package My::Schema::User;
	 ...
	 __PACKAGE__->table('users');
	 __PACKAGE__->add_columns(qw/ id name /);
	 __PACKAGE__->set_primary_key('id');
	 ...
	 1;

	 package My::Schema::ACL;
	 ...
	 __PACKAGE__->table('acl');
	 __PACKAGE__->add_columns(qw/ user_id /);
	 __PACKAGE__->belongs_to( 'user' => 'My::Schema::User', 'user_id' );
	 ...
	 1;

	 $schema->resultset('ACL')->search(
	   {},
	   {
	     join => [qw/ user /],
	     '+select' => [ 'user.name' ]
	   }
	 );

       The SQL generated would resemble something like:

	 SELECT me.user_id, user.name FROM acl me
	 JOIN users user ON me.user_id = user.id

       If, as is likely, your database treats "user" as a reserved word, you'd end up with the following errors:

       1) syntax error at or near "." - due to "user.name" in the SELECT clause

       2) syntax error at or near "user" - due to "user" in the JOIN clause

       The solution is to enable quoting - see "Setting_quoting_for_the_generated_SQL" in DBIx::Class::Manual::Cookbook for details.

   column "foo DESC" does not exist ...
       This can happen if you are still using the obsolete order hack, and also happen to turn on SQL-quoting.

	 $rs->search( {}, { order_by => [ 'name DESC' ] } );

       Since DBIx::Class >= 0.08100 and SQL::Abstract >= 1.50 the above should be written as:

	 $rs->search( {}, { order_by => { -desc => 'name' } } );

       For more ways to express order clauses refer to "ORDER_BY_CLAUSES" in SQL::Abstract

   Perl Performance Issues on Red Hat Systems
       There is a problem with slow performance of certain DBIx::Class operations using the system perl on some Fedora and Red Hat Enterprise
       Linux system (as well as their derivative distributions such as Centos, White Box and Scientific Linux).

       Distributions affected include Fedora 5 through to Fedora 8 and RHEL5 upto and including RHEL5 Update 2. Fedora 9 (which uses perl 5.10)
       has never been affected - this is purely a perl 5.8.8 issue.

       As of September 2008 the following packages are known to be fixed and so free of this performance issue (this means all Fedora and RHEL5
       systems with full current updates will not be subject to this problem):-

	 Fedora 8     - perl-5.8.8-41.fc8
	 RHEL5	      - perl-5.8.8-15.el5_2.1

       This issue is due to perl doing an exhaustive search of blessed objects under certain circumstances.  The problem shows up as performance
       degradation exponential to the number of DBIx::Class row objects in memory, so can be unnoticeable with certain data sets, but with huge
       performance impacts on other datasets.

       A pair of tests for susceptibility to the issue and performance effects of the bless/overload problem can be found in the DBIx::Class test
       suite, in the "t/99rh_perl_perf_bug.t" file.

       Further information on this issue can be found in <https://bugzilla.redhat.com/show_bug.cgi?id=379791>,
       <https://bugzilla.redhat.com/show_bug.cgi?id=460308> and http://rhn.redhat.com/errata/RHBA-2008-0876.html
       <http://rhn.redhat.com/errata/RHBA-2008-0876.html>

   Excessive Memory Allocation with TEXT/BLOB/etc. Columns and Large LongReadLen
       It has been observed, using DBD::ODBC, that creating a DBIx::Class::Row object which includes a column of data type TEXT/BLOB/etc. will
       allocate LongReadLen bytes.  This allocation does not leak, but if LongReadLen is large in size, and many such row objects are created,
       e.g. as the output of a ResultSet query, the memory footprint of the Perl interpreter can grow very large.

       The solution is to use the smallest practical value for LongReadLen.

perl v5.14.2							    2010-06-03				 DBIx::Class::Manual::Troubleshooting(3pm)