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AdministeringIn addition to administering the database server, you can tune performance, replicate data, and archive data.
System administrationThese topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL OneDB™ database servers.
Performance GuideThe HCL OneDB™ Performance Guide describes how to configure and operate your HCL OneDB™ database server to improve overall system throughput and to improve the performance of SQL queries.
Queries and the query optimizerThese topics describe query plans, explain how the database server manages query optimization, and discuss factors that you can use to influence the query plan. These topics also describe performance considerations for SPL routines, the UDR cache, and triggers.
The query planThe query optimizer evaluates the different ways in which a query might be performed and determines the best way to select the requested data. During this evaluation, the optimizer formulates a query plan to fetch the data rows that are required to process a query.
Report that shows the query plan chosen by the optimizerAny user who runs a query can use the SET EXPLAIN statement or the EXPLAIN directive to display the query plan that the optimizer chooses.

Report that shows the query plan chosen by the optimizer

Any user who runs a query can use the SET EXPLAIN statement or the EXPLAIN directive to display the query plan that the optimizer chooses.

For information about how to specify the directives, see EXPLAIN directives. The user enters the SET EXPLAIN ON statement or the SET EXPLAIN ON AVOID_EXECUTE statement before the SQL statement for the query, as the following example shows.

SET EXPLAIN ON AVOID_EXECUTE;
SELECT * FROM customer, orders
WHERE customer.customer_num = orders.customer_num
   AND customer.lname = "Higgins";

If a user does not have any access to SQL code source, the Database Administrator can set dynamically the SET EXPLAIN using the onmode -Y command.

After the database server executes the SET EXPLAIN ON statement or sets dynamically the SET EXPLAIN with onmode -Y command, the server writes an explanation of each query plan to a file for subsequent queries that the user enters.