NAME
CHI::Driver::DBI - Use DBI for cache storage
VERSION
version 1.24
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.
SCHEMA
Each namespace requires a table like this:
CREATE TABLE chi_<namespace> (
`key` VARCHAR(...),
`value` TEXT,
PRIMARY KEY (`key`)
)
The size of the key column depends on how large you want keys to be and
may be limited by the maximum size of an indexed column in your
database.
The driver will attempt to create the table for you if you pass
CONSTRUCTOR PARAMETERS
create_table
Boolean. If true, attempt to create the database table if it does
not already exist. Defaults to false.
namespace
The namespace you pass in will be appended to the `table_prefix' to
form the 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.
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.
AUTHOR
Jonathan Swartz <
[email protected]>
COPYRIGHT AND LICENSE
This software is copyright (c) 2011 by Jonathan Swartz.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
