How much string content can I store in an option?

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I am about to create a new plugin that fetches remote content and stores it locally for use on the WP website. I have a free plugin that does this with twitter and tweets, and I store a JSON file in the plugin directory. Some users complain that the plugin cannot write files to the folder due to permissions.

For this reason, I have been thinking about storing the remote content for this new plugin in an option. Is 250kb of HTML too big for an option? Is there another API call that can help me store a large chunk of string data?

3 Answers
3

Look at the table schema in wp-admin/includes/schema.php:

// regular blog tables
CREATE TABLE $wpdb->options (
  option_id bigint(20) unsigned NOT NULL auto_increment,
  option_name varchar(64) NOT NULL default '',
  option_value longtext NOT NULL,
  autoload varchar(20) NOT NULL default 'yes',
  PRIMARY KEY  (option_id),
  UNIQUE KEY option_name (option_name)
) $charset_collate;

// Multisite options
CREATE TABLE $wpdb->sitemeta (
  meta_id bigint(20) NOT NULL auto_increment,
  site_id bigint(20) NOT NULL default '0',
  meta_key varchar(255) default NULL,
  meta_value longtext,
  PRIMARY KEY  (meta_id),
  KEY meta_key (meta_key),
  KEY site_id (site_id)
) $charset_collate;

In both cases the value is longtext. The MySQL manual says about that type:

A TEXT column with a maximum length of 4,294,967,295 or 4GB (232 – 1) characters. The effective maximum length is less if the value contains multi-byte characters. The effective maximum length of LONGTEXT columns also depends on the configured maximum packet size in the client/server protocol and available memory. Each LONGTEXT value is stored using a 4-byte length prefix that indicates the number of bytes in the value.

4GB. If that is not enough improve the clean-up process. Maybe you should store the content as a file anyway – in the uploads directory.

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