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DBIx::Class::Manual::TUserlContributed)DBIx::Class::Manual::Troubleshooting(3)

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
       up to 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 result 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>

   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 result 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.

FURTHER	QUESTIONS?
       Check the list of additional DBIC resources.

COPYRIGHT AND LICENSE
       This module is free software copyright by the DBIx::Class (DBIC)
       authors.	You can	redistribute it	and/or modify it under the same	terms
       as the DBIx::Class library.

perl v5.24.1			  2016-DBIx::Class::Manual::Troubleshooting(3)

NAME | FURTHER QUESTIONS? | COPYRIGHT AND LICENSE

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