Why is this MySQL FULLTEXT query returning 0 rows when matching rows are present?

Posted by Don MacAskill on Server Fault See other posts from Server Fault or by Don MacAskill
Published on 2011-03-04T23:19:11Z Indexed on 2011/03/04 23:26 UTC
Read the original article Hit count: 195

Filed under:

mysql

I have a MySQL table with >200M rows which has a FULLTEXT index on two columns (Title,Body).

When I do a simple FULLTEXT query in the default NATURAL LANGUAGE mode for some popular results (they'd return 2M+ rows), I'm getting zero rows back:

SELECT COUNT(*) FROM itemsearch WHERE MATCH (Title, Body) AGAINST ('fubar');

But when I do a FULLTEXT query in BOOLEAN mode, I can see the rows in question do exist (I get 2M+ back, depending):

SELECT COUNT(*) FROM itemsearch WHERE MATCH (Title, Body) AGAINST ('+fubar' IN BOOLEAN MODE);

I have some queries which return ~500K rows which are working fine in either mode, so if it's result size related, it seems to crop up somewhere between 500K and a little north of 2M.

I've tried playing with the various buffer size variables, to no avail. It's clearly not the 50% threshold, since we're not getting 100M rows back for any result.

Any ideas?

Related posts about mysql

How to remove MySQL completely with config and library files on ubuntu 12.04 gnome 3.0

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I tried everything till now: sudo apt-get remove mysql-server mysql-client mysql-common sudo apt-get purge mysql-server mysql-client mysql-common sudo apt-get autoremove and even more commands... But whenever I am trying to locate mysql. I get a no. of files related to mysql command: shell>>… >>> More
mysql: Cannot load from mysql.proc. The table is probably corrupted

as seen on Server Fault - Search for 'Server Fault'
Mysql was started: /usr/bin/mysqld_safe --datadir=/srv/mysql/myDB --log-error=/srv/mysql/logs/mysqld-myDB.log --pid-file=/srv/mysql/pids/mysqld-myDB.pid --user=mysql --socket=/srv/mysql/sockets/mysql-myDB.sock --port=3700 but when I'm trying to do something: ERROR 1548 (HY000) at line 1: Cannot… >>> More
Why is there a /etc/init.d/mysql file on this Slackware machine? How could it have gotten there?

as seen on Server Fault - Search for 'Server Fault'
A client of my IT-consulting service owns a web-development shop. He's been having problems with a Slackware 12.0 server running MySQL 5.0.67. The machine was set up by the client's sysadmin, who left on bad terms. My client no longer employs a sysadmin. As far as I can tell, the only copy of MySQL… >>> More
mysql: Bind on unix socket: Permission denied

as seen on Server Fault - Search for 'Server Fault'
Can't start mysql with: sudo /usr/bin/mysqld_safe --datadir=/srv/mysql/myDB --log-error=/srv/mysql/logs/mysqld-myDB.log --pid-file=/srv/mysql/pids/mysqld-myDB.pid --user=mysql --socket=/srv/mysql/sockets/mysql-myDB.sock --port=3700 120222 13:40:48 mysqld_safe Starting mysqld daemon with databases… >>> More
MySQL – Learning MySQL Online in 6 Hours – MySQL Fundamentals in 320 Minutes

as seen on SQL Authority - Search for 'SQL Authority'
MySQL is one of the most popular database language and I have been recently working with it a lot. Data have no barrier and every database have their own place. I have been working with MySQL for quite a while and just like SQL Server, I often find lots of people asking me if I have a tutorial which… >>> More

Developer IT