Question

I’m building a tweet database with PHP and MySQL using the Twitter streaming API. Along with the “tweets” table, there are separate tables to keep track of mentions, urls, hashtags and users.

I have it periodically checking and only keeping the most recent 1000 tweets for each of my keywords, deleting the rest from the database. What I would like to do is clean up the data in the associated tables as well (By associated tables, I mean the mentions, urls, hashtags and users tables).

I’m wondering what the most efficient way to delete all mentions, urls, hashtags and users that do not have a matching tweet_id in the “tweets” table would be.

Table structures:

--
-- Table structure for table `tweets`
--

CREATE TABLE IF NOT EXISTS `tweets` (
  `tweet_id` bigint(20) unsigned NOT NULL,
  `tweet_text` varchar(200) NOT NULL,
  `entities` text NOT NULL,
  `created_at` datetime NOT NULL,
  `geo_lat` decimal(10,5) DEFAULT NULL,
  `geo_long` decimal(10,5) DEFAULT NULL,
  `user_id` int(10) unsigned NOT NULL,
  `screen_name` char(20) NOT NULL,
  `name` varchar(40) DEFAULT NULL,
  `profile_image_url` varchar(200) DEFAULT NULL,
  `tweet_keywords` varchar(128) NOT NULL,
  PRIMARY KEY (`tweet_id`),
  KEY `created_at` (`created_at`),
  KEY `user_id` (`user_id`),
  KEY `screen_name` (`screen_name`),
  KEY `name` (`name`),
  FULLTEXT KEY `tweet_text` (`tweet_text`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

-- --------------------------------------------------------

--
-- Table structure for table `tweet_mentions`
--

CREATE TABLE IF NOT EXISTS `tweet_mentions` (
  `tweet_id` bigint(20) NOT NULL,
  `source_user_id` bigint(20) NOT NULL,
  `target_user_id` bigint(20) NOT NULL,
  KEY `tweet_id` (`tweet_id`),
  KEY `source` (`source_user_id`),
  KEY `target` (`target_user_id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

-- --------------------------------------------------------

--
-- Table structure for table `tweet_tags`
--

CREATE TABLE IF NOT EXISTS `tweet_tags` (
  `tweet_id` bigint(20) NOT NULL,
  `tag` varchar(100) NOT NULL,
  KEY `tweet_id` (`tweet_id`),
  KEY `tag` (`tag`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

-- --------------------------------------------------------

--
-- Table structure for table `tweet_urls`
--

CREATE TABLE IF NOT EXISTS `tweet_urls` (
  `tweet_id` bigint(20) NOT NULL,
  `url` varchar(140) NOT NULL,
  KEY `tweet_id` (`tweet_id`),
  KEY `url` (`url`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

-- --------------------------------------------------------

--
-- Table structure for table `users`
--

CREATE TABLE IF NOT EXISTS `users` (
  `user_id` bigint(20) unsigned NOT NULL,
  `screen_name` varchar(20) NOT NULL,
  `name` varchar(40) DEFAULT NULL,
  `profile_image_url` varchar(200) DEFAULT NULL,
  `location` varchar(30) DEFAULT NULL,
  `url` varchar(200) DEFAULT NULL,
  `description` varchar(200) DEFAULT NULL,
  `created_at` datetime NOT NULL,
  `followers_count` int(10) unsigned DEFAULT NULL,
  `friends_count` int(10) unsigned DEFAULT NULL,
  `statuses_count` int(10) unsigned DEFAULT NULL,
  `time_zone` varchar(40) DEFAULT NULL,
  `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`user_id`),
  KEY `user_name` (`name`),
  KEY `last_update` (`last_update`),
  KEY `screen_name` (`screen_name`),
  FULLTEXT KEY `description` (`description`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

Answer 1

Have a look at foreign key constraints.