mysql full text search error

I try to add full text search to an existing table. When I tried:

alter table tweets add fulltext index(tags);

I got the error:

ERROR 1214 (HY000): The used table type d开发者_StackOverflowoesn't support FULLTEXT indexes

what is the problem? How can I know what table type it is?

If you want to use full text indexing you need to make sure your table's underlying engine is MyISAM. You can change this using ALTER TABLE tweets ENGINE = MYISAM;

This is how you check the table type:

SELECT table_schema,engine FROM information_schema.tables WHERE table_name='tweet';

Only MyISAM supports FULLTEXT Indexes.

You may also want to preempt the stopword list.

Click Here for the Stop Words that FullText Indexing Would Normally Ignore.

You can override this as Follows:

1) Create a text file in /var/lib/mysql like this

echo "a" > /var/lib/mysql/stopwords.txt<BR>
echo "an" >> /var/lib/mysql/stopwords.txt<BR>
echo "the" >> /var/lib/mysql/stopwords.txt<BR>

2) Add this to /etc/my.cnf

ft_stopword_file=/var/lib/mysql/stopwords.txt<BR>
ft_min_word_len=2

3) service mysql restart

Here is something else to consider:

You may not want to convert the table 'tweets' to MyISAM.

1) If the InnoDB table 'tweets' contains CONSTRAINT(s).

2) If the InnoDB table 'tweets' is the parent of other InnoDB tables with Foreign Key Constraints back to 'tweets'.

3) You cannot afford to have table-level locking of the 'tweets' table.

Remember, each INSERT into the 'tweets' table will trigger a table-level lock if it were a MyISAM table. Since it currently an InnoDB table (which does row-level locking), the 'tweets' table can be INSERTed into very quickly.

You many want to create a separate MyISAM table, called tweets_tags, with the same Primary Key of the 'tweets' table along with a TEXT column called 'tags' the same as in the 'tweets' table.

Next, do an initial load of tweets_tags like this:

INSERT INTO tweets_tags (id,tags) SELECT id,tags FROM tweets;

Then, periodically (every night or every 6 hours), load new tweets into tweets_tags like this :

INSERT INTO tweets_tags (id,tags) SELECT id,tags FROM tweets WHERE id > (SELECT max(id) FROM tweets_tags);