SQL Async Multiple Queries Combine Results — Maximum Results (Top XYZ)

Question

I have a search function set up, where I run multiple queries simultaneously. The top 1000 results of each query are written to a table. (These run async--I am just leaving out

Answer 1

insert into #tt2 
SELECT TOP 1000 [sID]
FROM [docSVsys]
where (select count(*) from #tt2) < 1000

But I would still use .NET and TPL.

This will still process all tables but it should process 0 rows once it gets to 1000

Answer 2

The following SQL limits the number of rows to 4 from any subsequent query

SET ROWCOUNT 4

SET @Rows = @@ROWCOUNT

Get the number of rows form the preceeding select

so something like

SELECT TOP etc...

SET @Rows = @@ROWCOUNT

SET ROWCOUNT 1000 - @Rows

Will probably error if @row goes below zero

but you an trap this with IF and goto PROC_LABLE

Answer 3

The following will likely give you a plan that achieves your desired result of not processing any rows after the 1,000th one has been found.

WITH CTE
     AS (SELECT Text
         FROM   A
         WHERE  CONTAINS(Text, '"searchString"')
         UNION ALL
         SELECT Text
         FROM   B
         WHERE  CONTAINS(Text, '"searchString"')
         UNION ALL
         SELECT Text
         FROM   C
         WHERE  CONTAINS(Text, '"searchString"'))
INSERT INTO Results
SELECT TOP 1000 Text
FROM   CTE 

Answer 4

If you setup your result table with an identity column you can achieve your goal using this query (let 'counter' be that column. don't forget to put an index on it)

declare @remaining int
select @remaining = 1000 - (max(counter) - min(counter) + 1) from result
if @result>0
  insert into Result (Text) select top (@remaining) Text from MyTable

Also, if you have a list of table names, you can use a while loop and exit if @result is 0.