Diagnosing the Database and Managing Performance - OCP: Oracle Database 12c Administrator Certified Professional - page 418

Chapter 11, “Creating Oracle Multitenant Databases,” describes container
databases and pluggable databases in detail. At this point, you need to
know that a CDB may contain zero or more PDBs, and a PDB is a collection
of schemas, schema objects, and non-schema objects that would appear
to be an independent database. Also, a common user is a database user
that has the same identity in the root container and in every PDB in a CDB.
Manual SQL Tuning Advisor
It is common for SQL statements to not meet performance expectations, so the DBA will need
to intervene to improve performance. Use the SQL Tuning Advisor when a performance situ-
ation occurs to determine how to improve the performance of the SQL statements. To run the
SQL Tuning Advisor on demand, we will utilize the Tuning Advisor in Enterprise Manager.
1. From the database home page in EM, select Performance ➢ SQL ➢ SQL Tuning Advi-
sor, as shown in Figure 9.16, and you'll see the page in Figure 9.17, where you are asked
to schedule the Tuning Advisor to begin SQL tuning.
2. On the SQL Tuning Advisor page, input the parameters for collecting SQL statement
information, including scheduling information for task-data collection.
3. Click the SQL Tuning Sets link in the Overview section, or click the spyglass next to the
SQL Tuning Set text box to take you to the SQL Tuning Sets page, shown in Figure 9.18.
If there are no defined SQL tuning sets, then you have the opportunity to create a
new one.
FiGURe 9.16 Navigating to the SQL Tuning Advisor home page