Having ample memory reduces disk I/O, which improves performance, since memory access is much faster than disk access. When a user issues a query, the data and index pages must be in memory, or read into memory, in order to examine the values on them. If the pages already reside in memory, Adaptive Server does not need to perform disk I/O.
Adding more memory is cheap and easy, but developing around memory problems is expensive. Give Adaptive Server as much memory as possible.
Memory conditions that can cause poor performance are:
Total data cache size is too small.
Procedure cache size is too small.
Only the default cache is configured on an SMP system with several active CPUs, leading to contention for the data cache.
User-configured data cache sizes are not appropriate for specific user applications.
Configured I/O sizes are not appropriate for specific queries.
Audit queue size is not appropriate if auditing feature is installed.
