Question

I have a search query that takes a phrase typed in by the user and should return a result, here is an example:

SELECT rank,[KEY] FROM CONTAINSTABLE(tblproduct, (title,subtitle,publisher_name),  @search_text,15)

Where @search_text is

Set @search_text = '"my favourite word*"'

The phrase, as it stands, is an exact title match to a book in the database. However, the wildcard (*), makes it so that it doesn’t return ANY results.

When I omit the wildcard, I get an exact phrase match, however, some other phrases, like “The Imperfectionists” returns no results with or without the wildcard in place.

Why is this? What can I check?

Currently, if no result-set is generated for the wildcard, I run the query without the wildcard to see if it returns anything. If that fails too, I run a normal “like” statement.

Obviously the like statement will take forever… and I don’t want to use it on a 7.6 million-strong database for a search that’s supposed to be done with fulltext…

Any help appreciated!

Answer 1

Using JStead’s suggestion, I looked at the output for your string. I also found this at MSDN:

When is a phrase, each word contained in the phrase is
considered to be a separate prefix. Therefore, a query specifying a
prefix term of “local wine*” matches any rows with the text of “local
winery”, “locally wined and dined”, and so on.

So, the word My is considered a “Noise word” by default. Adding the * causes the parser to look for any words starting with My. However, when searching the index, the word My seems to already have been removed (remember, it’s a noise word), so it doesn’t find the match.

I’m thinking about running my search string through the sys.dm_fts_parser function, removing noise words, before adding the *.