Performance During Concurrency
When multiple users are concurrently working on the same set of tables, the following should be considered when evaluating performance:
• If tables are not being updated:
– Concurrency is not a performance problem.
– There are no deadlock problems.
• Mixed writers and readers of a table
– Concurrent performance is affected.
– Deadlocks can occur, causing reduced performance due to deadlock rollback.
Locks acquired during a multiple query transaction are held until the COMMIT statement is executed.
• Consider offloading tables where there is heavy concurrent activity to "work" or "session tables."
• READLOCK = NOLOCK can be beneficial.
• You can use the Visual Forms Editor’s form validations, rather than table-lookup validations that lock the reference table, because they are read only at form start-up time.