/ 
CHI-Driver-DBI-1.23
River stage zero No dependents
/ CHI::Driver::DBI

NAME

CHI::Driver::DBI - Use DBI for cache storage

SYNOPSIS

use CHI;

# Supply a DBI handle
#
my $cache = CHI->new( driver => 'DBI', dbh => DBI->connect(...) );

# or a DBIx::Connector
#
my $cache = CHI->new( driver => 'DBI', dbh => DBIx::Connector->new(...) );

# or code that generates a DBI handle
#
my $cache = CHI->new( driver => 'DBI', dbh => sub { ...; return $dbh } );

DESCRIPTION

This driver uses a database table to store the cache. The newest versions of MySQL and SQLite work are known to work. Other RDBMSes should work.

Why cache things in a database? Isn't the database what people are trying to avoid with caches? This is often true, but a simple primary key lookup is extremely fast in many databases and this provides a shared cache that can be used when less reliable storage like memcached is not appropriate. Also, the speed of simple lookups on MySQL when accessed over a local socket is very hard to beat. DBI is fast.

ATTRIBUTES

namespace

The namespace you pass in will be appended to the table_prefix and used as a table name. That means that if you don't specify a namespace or table_prefix the cache will be stored in a table called chi_Default.

table_prefix

This is the prefix that is used when building a table name. If you want to just use the namespace as a literal table name, set this to undef. Defaults to chi_.

dbh

The main, or rw, DBI handle used to communicate with the db. If a dbh_ro handle is defined then this handle will only be used for writing.

You may pass this handle, and dbh_ro below, in one of three forms:

  • a regular DBI handle

  • a DBIx::Connector object

  • a code reference that will be called each time and is expected to return a DBI handle, e.g.

    sub { My::Rose::DB->new->dbh }

The last two options are valuable if your CHI object is going to live for enough time that a single DBI handle might time out, etc.

dbh_ro

The optional DBI handle used for read-only operations. This is to support master/slave RDBMS setups.

sql_strings

Hashref of SQL strings to use in the different cache operations. The strings are built depending on the RDBMS that dbh is attached to.

METHODS

BUILD

Standard issue Moose BUILD method. Used to build the sql_strings. If the parameter create_table to new() was set to true, it will attempt to create the db table. For Mysql and SQLite the statement is "create if not exists..." so it's generally harmless.

fetch
store
remove
clear
get_keys
get_namespaces

Not supported at this time.

Authors

Original version by Justin DeVuyst and Perrin Harkins. Currently maintained by Jonathan Swartz.

COPYRIGHT & LICENSE

Copyright (C) Justin DeVuyst

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