When should you use full-text indexing?

Question

We have a whole bunch of queries that \"search\" for clients, customers, etc. You can search by first name, email, etc. We\'re using LIKE statements in the following manner:

Answer 1

According to my test scenario:

• SQL Server 2008
• 10.000.000 rows each with a string like "wordA wordB wordC..." (varies between 1 and 30 words)
• selecting count(*) with CONTAINS(column, "wordB")
• result size several hundred thousands
• catalog size approx 1.8GB

Full-text index was in range of 2s whereas like '% wordB %' was in range of 1-2 minutes.

But this counts only if you don't use any additional selection criteria! E.g. if I used some "like 'prefix%'" on a primary key column additionally, the performance was worse since the operation of going into the full-text index costs more than doing a string search in some fields (as long those are not too much).

So I would recommend full-text index only in cases where you have to do a "free string search" or use some of the special features of it...