SQL/MX 2.x Query Guide (G06.24+, H06.03+)

Reviewing Query Execution Plans
HP NonStop SQL/MX Query Guide—523728-003
4-23
Using Measure
other queries, frequency of execution within a single transaction, and other
performance-related measurements. Then, generate query plans with the Explain
function for the queries to help identify reasons for poor performance. Sometimes a
specific type of problem is common to a set of queries.
Stopwatch measurements can also be helpful. When compared to Measure
information, they can reveal network problems or other types of delays.
It can be important to establish response-time requirements for specific queries. This
strategy permits identification of a specific goal and completion framework for tuning.
When evaluating changes to queries, consider other transactions that might be
adversely affected by the change. For example, if you add an index, compare
performance before and after for INSERT and UPDATE transactions. Consider the
volume of the query being addressed and compare it with the volume of UPDATE and
DELETE transactions.