What is the importance of ft_query_expansion_limit?

[Garlic]

What is the importance of ft_query_expansion_limit and what exactly it’s doing?

from http://dev.mysql.com/doc/refman/5.0/en/server-system-variabl es.html

[B]Quote:[/B]

The number of top matches to use for full-text searches performed using WITH QUERY EXPANSION.

I don't unerstand what they mean by that.

[vgatto]

Basically, query expansion performs a full text search and then uses the first few results (configured by ft_query_expansion_limit) to search again and compose your result set. The explanation in the docs is probably better than mine:

http://dev.mysql.com/doc/refman/5.1/en/fulltext-query-expans ion.html

[Garlic]

Does increasing this value improves performance?

[vgatto]

Unless you are specifically using WITH QUERY EXPANSION in your fulltext queries, this will have no affect on performance.

[Garlic]

Thanks. I’ll remember that.