Question

I have a script that processes queued records in a SQL table in SQL Server 2000. I now need to add additional instances of my script to process their own subset of the queued records in the table.

How can I query the table within each instance so that each instance will return a subset of rows that never overlap with each other?

I could query the id row for odd numbers in one process and even numbers in another, but I’ll need to add more than 2 instances eventually.

CREATE TABLE requests (
   id int IDENTITY(1,1) NOT NULL,
   requestor VARCHAR(50),
   status INT,
   created DATETIME,
   queuetime DATETIME
)

The existing query for the single instance is:

SELECT * FROM requests WHERE status = 1 ORDER BY queuetime

Answer 1

Based, on your odd/even solution, it sounds like it doesn’t matter what sequence the requests are processed. So, maybe you could do something like this.

SELECT id, requestor, status, created, queuetime
FROM requests
WHERE status = 1
    AND ID % 3 + 1 = 2
ORDER BY queuetime

The 3 in the second condition represents the number of processes. The number 2 indicates the 2nd process.