Question

Hi all I have the following SQL Server 2008 script that will check if a row already exists in Table A and if it doesn’t insert the data from Table B.

This was working nicely until Table A started to fill up with a lot of data. We currently have 30 million rows in this table and this will continue to grow to a predicated 70 million rows.

The problem if this is taking far too long and is affecting other processes. Just wondering if there is a better way to check if a row already exists in a table. Just to add as well this is all done using an SSIS.

Script:

INSERT INTO TABLE A ([recordID],Field 1, Field2, Field 3, Field 4, Field 5) 
    SELECT 
        [TABLE B].[recordID],[TABLE B].[Field 1], [TABLE B].[Field2], 
        [TABLE B].[Field 3], [TABLE B].[Field 4], [TABLE B].[Field 5] 
    FROM TABLE B AS TABLE B 
    LEFT OUTER JOIN TABLE A AS TABLE A ON [TABLE B].[recordID] = [TABLE A].[recordID] 
    WHERE [TABLE A].[recordID] IS NULL

Answer 1

You can check the the Merge command:

http://technet.microsoft.com/en-us/library/bb510625.aspx