[JohnWoo]

Sorry for disappearing
Returning to discussion about SQL requests with or without LEFT JOIN
I recently had a chance to do a lot of tests on one large programming forum with about 900.000 posts. And yes - it is true that excluding some forums from searches do not make search run faster... But including left join don't make it perceptible slower
But after removing revelance it runs up to 10 times faster!
Here are results as requests and time in seconds below. Each request was executed 10 times with clearing DB cache after each. Fastest and slowest time below. Forums were not closed at that moment and there were about 120 online users. Think that numbers too different because of it

============
SELECT postid
FROM post AS post
LEFT JOIN thread AS thread ON post.threadid = thread.threadid
WHERE MATCH (
pagetext
)
AGAINST (
'+user +acces'
IN BOOLEAN
MODE 
)
LIMIT 0 , 200

0.0277 -  0.3782 s

============

excluding security forums

============
SELECT postid
FROM post AS post
LEFT JOIN thread AS thread ON post.threadid = thread.threadid
WHERE MATCH (
pagetext
)
AGAINST (
'+user +acces'
IN BOOLEAN
MODE 
) AND thread.forumid NOT IN (57, 64)
LIMIT 0 , 200

0.0197 - 0.2272 s
============

============
SELECT postid
FROM post AS post
WHERE MATCH (
pagetext
)
AGAINST (
'+user +acces*'
IN BOOLEAN
MODE 
)
LIMIT 0 , 200

0.0144 - 0.1043 s
============

============
SELECT postid, 
MATCH (
pagetext
)
AGAINST (
'user acces'
) AS relevance
FROM post AS post
LEFT JOIN thread AS thread ON post.threadid = thread.threadid
WHERE MATCH (
pagetext
)
AGAINST (
'+user +acces*'
IN BOOLEAN
MODE 
) AND thread.forumid NOT 
IN ( 57, 64 ) 
LIMIT 0 , 200

0.6938 - 1.3414 s
============

============
SELECT postid, 
MATCH (
pagetext
)
AGAINST (
'user acces'
) AS relevance
FROM post
WHERE MATCH (
pagetext
)
AGAINST (
'+user +acces*'
IN BOOLEAN
MODE 
)
LIMIT 0 , 200

0.5509 - 1.4414 s
============