Re: Full-Text on double rows

[Chris Nolan]

Lorderon wrote:

"Chris Nolan" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
 

Which version of MySQL?? The difference will be different (!!) depending
on the version in use.
In general, full text search uses a tree-structure. Doubling the number
of entries in the tree is likely to result in a time difference of not
very much at all!
   

Currently using version 4.0.16 but will move to 4.1 and 5 when they're
released.. How it works on those versions?
 

MySQL 4.1 introduced a two-level full-text search tree, which results in 
much better performance.

According to what you described as a tree-structure.. then spliting a big
full-text table into 2 smaller tables and use UNION just makes the situation
worse...
 

It would, as you've got two trees of comparable size to get through. To 
give you an idea, to find anything in a tree (in most cases), you're 
looking at time that's proportional to the log of the number of items in it.

Maths says that:

2 * log n >> log 2*n for the vast majority of n. In fact, it's 
equivalent to searching a tree with n*n nodes when searching two trees 
with n nodes.

thanks
-Lorderon.


 



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