FreeText Query is slow - includes TOP and Order By

Question

The Product table has 700K records in it. The query:

SELECT TOP 1 ID, Name FROM Product WHERE contains(Name, \'\"White Dress\"\') ORDER BY DateMadeN

Answer 1

Edit

From http://technet.microsoft.com/en-us/library/cc721269.aspx#_Toc202506240

The most important thing is that the correct join type is picked for full-text query. Cardinality estimation on the FulltextMatch STVF is very important for the right plan. So the first thing to check is the FulltextMatch cardinality estimation. This is the estimated number of hits in the index for the full-text search string. For example, in the query in Figure 3 this should be close to the number of documents containing the term ‘word’. In most cases it should be very accurate but if the estimate was off by a long way, you could generate bad plans. The estimation for single terms is normally very good, but estimating multiple terms such as phrases or AND queries is more complex since it is not possible to know what the intersection of terms in the index will be based on the frequency of the terms in the index. If the cardinality estimation is good, a bad plan probably is caused by the query optimizer cost model. The only way to fix the plan issue is to use a query hint to force a certain kind of join or OPTIMIZE FOR.

So it simply cannot know from the information it stores whether the 2 search terms together are likely to be quite independent or commonly found together. Maybe you should have 2 separate procedures one for single word queries that you let the optimiser do its stuff on and one for multi word procedures that you force a "good enough" plan on (sys.dm_fts_index_keywords might help if you don't want a one size fits all plan).

NB: Your single word procedure would likely need the WITH RECOMPILE option looking at this bit of the article.

In SQL Server 2008 full-text search we have the ability to alter the plan that is generated based on a cardinality estimation of the search term used. If the query plan is fixed (as it is in a parameterized query inside a stored procedure), this step does not take place. Therefore, the compiled plan always serves this query, even if this plan is not ideal for a given search term.

Original Answer

Your new plan still looks pretty bad though. It looks like it is only returning 1 row from the full text query part but scanning all 770159 rows in the Product table.

How does this perform?

CREATE TABLE #tempResults
(
ID int primary key,
Name varchar(200),
DateMadeNew datetime
)

INSERT INTO #tempResults
SELECT 
      ID, Name, DateMadeNew 
      FROM Product 
      WHERE contains(Name, '"White Dress"')


SELECT TOP 1
    *
    FROM #tempResults
    ORDER BY DateMadeNew desc