170 lines
5.7 KiB
Plaintext
170 lines
5.7 KiB
Plaintext
=head1 NAME
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DBIx::Class::Manual::Troubleshooting - Got a problem? Shoot it.
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=head2 "Can't locate storage blabla"
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You're trying to make a query on a non-connected schema. Make sure you got
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the current resultset from $schema->resultset('Artist') on a schema object
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you got back from connect().
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=head2 Tracing SQL
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The C<DBIC_TRACE> environment variable controls
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SQL tracing, so to see what is happening try
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export DBIC_TRACE=1
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Alternatively use the C<< storage->debug >> class method:-
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$schema->storage->debug(1);
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To send the output somewhere else set debugfh:-
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$schema->storage->debugfh(IO::File->new('/tmp/trace.out', 'w'));
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Alternatively you can do this with the environment variable, too:-
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export DBIC_TRACE="1=/tmp/trace.out"
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=head2 Can't locate method result_source_instance
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For some reason the table class in question didn't load fully, so the
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ResultSource object for it hasn't been created. Debug this class in
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isolation, then try loading the full schema again.
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=head2 Can't get last insert ID under Postgres with serial primary keys
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Older L<DBI> and L<DBD::Pg> versions do not handle C<last_insert_id>
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correctly, causing code that uses auto-incrementing primary key
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columns to fail with a message such as:
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Can't get last insert id at /.../DBIx/Class/Row.pm line 95
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In particular the RHEL 4 and FC3 Linux distributions both ship with
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combinations of L<DBI> and L<DBD::Pg> modules that do not work
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correctly.
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L<DBI> version 1.50 and L<DBD::Pg> 1.43 are known to work.
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=head2 Can't locate object method "source_name" via package
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There's likely a syntax error in the table class referred to elsewhere
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in this error message. In particular make sure that the package
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declaration is correct. For example, for a schema C< MySchema >
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you need to specify a fully qualified namespace: C< package MySchema::MyTable; >.
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=head2 syntax error at or near "<something>" ...
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This can happen if you have a relation whose name is a word reserved by your
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database, e.g. "user":
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package My::Schema::User;
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...
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__PACKAGE__->table('users');
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__PACKAGE__->add_columns(qw/ id name /);
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__PACKAGE__->set_primary_key('id');
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...
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1;
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package My::Schema::ACL;
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...
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__PACKAGE__->table('acl');
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__PACKAGE__->add_columns(qw/ user_id /);
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__PACKAGE__->belongs_to( 'user' => 'My::Schema::User', 'user_id' );
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...
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1;
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$schema->resultset('ACL')->search(
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{},
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{
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join => [qw/ user /],
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'+select' => [ 'user.name' ]
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}
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);
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The SQL generated would resemble something like:
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SELECT me.user_id, user.name FROM acl me
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JOIN users user ON me.user_id = user.id
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If, as is likely, your database treats "user" as a reserved word, you'd end
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up with the following errors:
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1) syntax error at or near "." - due to "user.name" in the SELECT clause
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2) syntax error at or near "user" - due to "user" in the JOIN clause
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The solution is to enable quoting - see
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L<DBIx::Class::Manual::Cookbook/Setting quoting for the generated SQL> for
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details.
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=head2 column "foo DESC" does not exist ...
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This can happen if you are still using the obsolete order hack, and also
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happen to turn on SQL-quoting.
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$rs->search( {}, { order_by => [ 'name DESC' ] } );
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The above should be written as:
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$rs->search( {}, { order_by => { -desc => 'name' } } );
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For more ways to express order clauses refer to
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L<SQL::Abstract::Classic/ORDER BY CLAUSES>
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=head2 Perl Performance Issues on Red Hat Systems
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There is a problem with slow performance of certain DBIx::Class
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operations using the system perl on some Fedora and Red Hat Enterprise
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Linux system (as well as their derivative distributions such as Centos,
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White Box and Scientific Linux).
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Distributions affected include Fedora 5 through to Fedora 8 and RHEL5
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up to and including RHEL5 Update 2. Fedora 9 (which uses perl 5.10) has
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never been affected - this is purely a perl 5.8.8 issue.
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As of September 2008 the following packages are known to be fixed and so
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free of this performance issue (this means all Fedora and RHEL5 systems
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with full current updates will not be subject to this problem):-
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Fedora 8 - perl-5.8.8-41.fc8
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RHEL5 - perl-5.8.8-15.el5_2.1
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This issue is due to perl doing an exhaustive search of blessed objects
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under certain circumstances. The problem shows up as performance
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degradation exponential to the number of L<DBIx::Class> result objects in
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memory, so can be unnoticeable with certain data sets, but with huge
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performance impacts on other datasets.
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A pair of tests for susceptibility to the issue and performance effects
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of the bless/overload problem can be found in the L<DBIx::Class> test
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suite, in the C<t/99rh_perl_perf_bug.t> file.
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Further information on this issue can be found in
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L<https://bugzilla.redhat.com/show_bug.cgi?id=379791>,
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L<https://bugzilla.redhat.com/show_bug.cgi?id=460308> and
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L<http://rhn.redhat.com/errata/RHBA-2008-0876.html>
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=head2 Excessive Memory Allocation with TEXT/BLOB/etc. Columns and Large LongReadLen
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It has been observed, using L<DBD::ODBC>, that creating a L<DBIx::Class::Row>
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object which includes a column of data type TEXT/BLOB/etc. will allocate
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LongReadLen bytes. This allocation does not leak, but if LongReadLen
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is large in size, and many such result objects are created, e.g. as the
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output of a ResultSet query, the memory footprint of the Perl interpreter
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can grow very large.
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The solution is to use the smallest practical value for LongReadLen.
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=head1 FURTHER QUESTIONS?
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Check the list of L<additional DBIC resources|DBIx::Class/GETTING HELP/SUPPORT>.
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=head1 COPYRIGHT AND LICENSE
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This module is free software L<copyright|DBIx::Class/COPYRIGHT AND LICENSE>
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by the L<DBIx::Class (DBIC) authors|DBIx::Class/AUTHORS>. You can
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redistribute it and/or modify it under the same terms as the
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L<DBIx::Class library|DBIx::Class/COPYRIGHT AND LICENSE>.
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