Best practices for multithreaded processing of database records

Question

I have a single process that queries a table for records where PROCESS_IND = \'N\', does some processing, and then updates the PROCESS_IND to \'Y\'

Answer 1

Although I understand the intention I would disagree on going to row level locking immediately. This will reduce your response time and may actually make your situation worse. If after testing you are seeing concurrency issues with APL you should do an iterative move to “datapage” locking first!

To really answer this question properly more information would be required about the table structure and the indexes involved, but to explain further.

DOL, datarow locking uses a lot more locks than allpage/page level locking. The overhead in managing all the locks and hence the decrease of available memory due to requests for more lock structures within the cache will decrease performance and counter any gains you may have by moving to a more concurrent approach.

Test your approach without the move first on APL (all page locking ‘default’) then if issues are seen move to DOL (datapage first then datarow). Keep in mind when you switch a table to DOL all responses on that table become slightly worse, the table uses more space and the table becomes more prone to fragmentation which requires regular maintenance.

So in short don’t move to datarows straight off try your concurrency approach first then if there are issues use datapage locking first then last resort datarows.