Getting Startedwith pureQuery

Chapter 6 – The Client Optimizer: pureQuery for Existing Applications 97
5.2.2 Gathering and viewing explain data
You can gain insight into the health of your SQL statements by obtaining information such
as the predicted cost, whether indexes are used, or the number of joins used for
example—Oracle and IBM databases, including IDS, are supported.
To view explain information, right-click on the SQL Outline and select Show DataShow
EXPLAIN Data. If you would like to see this explain information for a specific SQL
statement, right-click on the statement in the SQL Outline and select Retrieve EXPLAIN
Data from the context menu. To retrieve the explain information for all statements within an
application right-click on the Java project and select Properties. On the left-hand-side
expand the pureQuery category and select Background EXPLAIN. Then select to Enable
project specific settings and to Enable Background EXPLAIN and click OK. Explain
information will start to be gathered for all of the statements in the SQL Outline belonging
to that specific Java project. Once all the explain data has been gathered, it will
automatically show next to SQL statements if you have chosen to view EXPLAIN Data in
the SQL Outline as shown in Figure 5.5.
Figure 5.5 - View explain information for SQL statements within your application
You can also change the view of the SQL Outline to show in a table format—Figure 5.4—in
order to sort the columns if you are interested in finding the statement with the highest cost,
for example.
5.3 Optimizing your application for performance
Once you have identified which statements take the longest to execute or any other
statement that you believe needs optimizing you can do one or a combination of the
following:
• replace a poorly performing statement with an optimized one using the
pureQueryXML Editor