Question

We’re using SqlServer 2008. In SSMS, queries on the full text catalog might take 2-5 seconds the first time, but after that, return quite quickly.

On the other hand, running a query from via Linq2Sql will timeout.

Here’s what we have:

The SQL Inline Table UDF

CREATE FUNCTION dbo.SearchArchiveFTS
(   
    @query nvarchar(255)
)
RETURNS @ret TABLE 
(
            ID      NVarChar(12) NOT NULL,
            snapshotDate    DateTime NOT NULL,
            -- about 10 more
)
AS BEGIN
    declare @innerQuery nvarchar(255)
    set @innerQuery = @query
    insert into @ret
    select      ID,
                snapshotDate,
                -- about 10 more
        from dbo.Archive a
        where contains(a.*, @innerQuery)
    return

Query in SSMS

select * from dbo.SearchArchiveFTS('query')
//3 seconds / 3k rows

Query in Linq2Sql

db.SearchArchiveFTS("query").ToArray();
// timeout exception

Any ideas on what the problem might be?

Answer 1

The issue appears to be related to a feature of SQL Server, where the FTS indices are unloaded after a period of inactivity. A background job to keep them fresh solved the problem.