mySQL MATCH across multiple tables

Question

I have a set of 4 tables that I want to search across. Each has a full text index. Can a query make use of every index?

CREATE TABLE `categories` (
  `id` int(5) unsigned NOT NULL auto_increment,
  `display_order` int(5) unsigned default NULL,
  `name` varchar(64) default NULL,
  `last_modified` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`),
  UNIQUE KEY `order` (`display_order`),
  FULLTEXT KEY `full_name` (`name`)
) ENGINE=MyISAM AUTO_INCREMENT=6 DEFAULT CHARSET=latin1;

CREATE TABLE `host_types` (
  `id` int(5) unsigned NOT NULL auto_increment,
  `category_id` int(5) unsigned default NULL,
  `display_order` int(5) unsigned default NULL,
  `name` varchar(64) default NULL,
  `last_modified` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`),
  UNIQUE KEY `order` (`category_id`,`display_order`),
  FULLTEXT KEY `full_name` (`name`)
) ENGINE=MyISAM AUTO_INCREMENT=13 DEFAULT CHARSET=latin1;


CREATE TABLE `hosts` (
  `id` int(5) unsigned NOT NULL auto_increment,
  `host_id` int(5) unsigned default NULL,
  `display_order` int(5) unsigned default NULL,
  `name` varchar(64) default NULL,
  `last_modified` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`),
  UNIQUE KEY `order` (`host_id`,`display_order`),
  FULLTEXT KEY `full_name` (`name`)
) ENGINE=MyISAM AUTO_INCREMENT=4 DEFAULT CHARSET=latin1;


CREATE TABLE `products` (
  `id` int(11) unsigned NOT NULL auto_increment,
  `host_id` int(5) unsigned default NULL,
  `display_order` int(5) unsigned default NULL,
  `uid` varchar(10) default NULL,
  `name` varchar(128) default NULL,
  `keywords` text,
  `description` text,
  `price` decimal(10,2) default NULL,
  `quantity` int(11) unsigned default NULL,
  `last_modified` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`),
  FULLTEXT KEY `full_name` (`name`,`keywords`,`description`,`uid`)
) ENGINE=MyISAM AUTO_INCREMENT=14 DEFAULT CHARSET=latin1;

Here is my query;

SELECT categories.name AS category, 
  categories.id AS category_id, 
  host_types.name AS host_type, 
  host_types.id AS host_type_id, 
  hosts.name AS host, 
  hosts.id AS host_id, 
  products.name as name, 
  products.id AS product_id, 
  products.keywords as keywords, 
  products.description AS description, 
  products.quantity AS quantity, 
  products.price AS price, 
  products.uid as catalogue, 
  MATCH(categories.name, host_types.name, hosts.name, products.name, 
      products.keywords, products.description, products.uid) 
      AGAINST('search term') as score 
FROM products 
LEFT JOIN hosts ON products.host_id = hosts.id 
LEFT JOIN host_types ON hosts.host_id = host_types.id 
LEFT JOIN categories ON host_types.category_id = categories.id 
WHERE MATCH(categories.name, host_types.name, hosts.name, products.name, 
            products.keywords, products.description, products.uid) 
      AGAINST('search term') 
ORDER BY score DESC;

• categories.name == FULLTEXT - 1
• host_types.name == FULLTEXT - 2
• hosts.name == FULLTEXT - 3
• products.name, products.keywords, products.description, products.uid == FULLTEXT - 4

---

Here is my SQL structure, and I used the above Query.

SELECT 
    categories.name AS category, 
    categories.id AS category_id, 
    host_types.name AS host_type, 
    host_types.id AS host_type_id, 
    hosts.name AS host, 
    hosts.id AS host_id, 
    products.name as name, 
    products.id AS product_id, 
    products.keywords as keywords, 
    products.description AS description, 
    products.quantity AS quantity, 
    products.price AS price, 
    products.uid as catalgue 
  MATCH(categories.name) AGAINST('search term') as cscore, 
  MATCH(host_types.name) AGAINST('search term') as htscore,
  MATCH(hosts.name) AGAINST('search term') as hscore,
  MATCH(products.name, products.keywords, products.description, products.uid)
    AGAINST('search term') as score
FROM products
LEFT JOIN hosts ON products.host_id = hosts.id
LEFT JOIN host_types ON hosts.host_id = host_types.id
LEFT JOIN categories ON host_types.category_id = categories.id
WHERE
  MATCH(categories.name) AGAINST('search term') OR
  MATCH(host_types.name) AGAINST('search term') OR
  MATCH(hosts.name) AGAINST('search term') OR
  MATCH(products.name, products.keywords, products.description, products.uid)
    AGAINST('search term')
ORDER BY score DESC



        CREATE TABLE `categories` (
  `id` int(5) unsigned NOT NULL auto_increment,
  `display_order` int(5) unsigned default NULL,
  `name` varchar(64) default NULL,
  `last_modified` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`),
  UNIQUE KEY `order` (`display_order`),
  FULLTEXT KEY `full_name` (`name`)
) ENGINE=MyISAM AUTO_INCREMENT=6 DEFAULT CHARSET=latin1;

CREATE TABLE `host_types` (
  `id` int(5) unsigned NOT NULL auto_increment,
  `category_id` int(5) unsigned default NULL,
  `display_order` int(5) unsigned default NULL,
  `name` varchar(64) default NULL,
  `last_modified` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`),
  UNIQUE KEY `order` (`category_id`,`display_order`),
  FULLTEXT KEY `full_name` (`name`)
) ENGINE=MyISAM AUTO_INCREMENT=13 DEFAULT CHARSET=latin1;


CREATE TABLE `hosts` (
  `id` int(5) unsigned NOT NULL auto_increment,
  `host_id` int(5) unsigned default NULL,
  `display_order` int(5) unsigned default NULL,
  `name` varchar(64) default NULL,
  `last_modified` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`),
  UNIQUE KEY `order` (`host_id`,`display_order`),
  FULLTEXT KEY `full_name` (`name`)
) ENGINE=MyISAM AUTO_INCREMENT=4 DEFAULT CHARSET=latin1;


CREATE TABLE `products` (
  `id` int(11) unsigned NOT NULL auto_increment,
  `host_id` int(5) unsigned default NULL,
  `display_order` int(5) unsigned default NULL,
  `uid` varchar(10) default NULL,
  `name` varchar(128) default NULL,
  `keywords` text,
  `description` text,
  `price` decimal(10,2) default NULL,
  `quantity` int(11) unsigned default NULL,
  `last_modified` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`),
  FULLTEXT KEY `full_name` (`name`,`keywords`,`description`,`uid`)
) ENGINE=MyISAM AUTO_INCREMENT=14 DEFAULT CHARSET=latin1;

Answer 1

• You can't define fulltext indexes (or any kind of index) across multiple tables in MySQL. Each index definition references exactly one table. All columns in a given fulltext index must be from the same table.

• The columns named as arguments to the MATCH() function must be part of a single fulltext index. You can't use a single call to MATCH() to search all columns that are part of all fulltext indexes in your database.

• Fulltext indexes only index columns defined with CHAR, VARCHAR, and TEXT datatypes.

• You can define a fulltext index in each table.

Example:

CREATE TABLE categories (
  id SERIAL PRIMARY KEY,
  name VARCHAR(100),
  FULLTEXT INDEX ftcat (name)
);

CREATE TABLE host_types (
  id SERIAL PRIMARY KEY,
  category_id BIGINT UNSIGNED,
  name VARCHAR(100),
  FULLTEXT INDEX ftht (name)
);

CREATE TABLE hosts (
  id SERIAL PRIMARY KEY,
  host_id BIGINT UNSIGNED,
  category_id BIGINT UNSIGNED,
  name VARCHAR(100),
  FULLTEXT INDEX fthost (name)
);

CREATE TABLE products (
  id SERIAL PRIMARY KEY,
  name VARCHAR(100),
  keywords VARCHAR(100),
  uid VARCHAR(100),
  description VARCHAR(100),
  quantity INTEGER,
  price NUMERIC(9,2),
  host_id BIGINT UNSIGNED,
  FULLTEXT INDEX ftprod (name, keywords, description, uid)
);

And then you can write a query that uses each respective fulltext index:

SELECT ...
  MATCH(categories.name) AGAINST('search term') as cscore, 
  MATCH(host_types.name) AGAINST('search term') as htscore,
  MATCH(hosts.name) AGAINST('search term') as hscore,
  MATCH(products.name, products.keywords, products.description, products.uid)
    AGAINST('search term') as score
FROM products
LEFT JOIN hosts ON products.host_id = hosts.id
LEFT JOIN host_types ON hosts.host_id = host_types.id
LEFT JOIN categories ON host_types.category_id = categories.id
WHERE
  MATCH(categories.name) AGAINST('search term') OR
  MATCH(host_types.name) AGAINST('search term') OR
  MATCH(hosts.name) AGAINST('search term') OR
  MATCH(products.name, products.keywords, products.description, products.uid)
    AGAINST('search term')
ORDER BY score DESC;