To configure and enable Database Smart Flash Cache, you must set the DB_FLASH_CACHE_SIZE

parameter to reflect the combined size of the flash devices you intend to use for the cache. In this

scenario, two flash devices are configured: /dev/sdj with 128G and /dev/sdk with 64G.

Determine the combined size of the flash devices intended for the Database Smart Flash Cache. In

this case, it's 128G + 64G = 192G.

However, Oracle documentation suggests setting DB_FLASH_CACHE_SIZE to the exact sizes of the

individual devices, separated by a comma when multiple devices are used.

Modify the parameter in the database initialization file (init.ora or spfile.ora) or using an ALTER

SYSTEM command. Here's the command for altering the system setting:

ALTER SYSTEM SET DB_FLASH_CACHE_SIZE='128G,64G' SCOPE=SPFILE;

Since this is a static parameter, a database restart is required for the changes to take effect.

Upon database startup, it will allocate the Database Smart Flash Cache using the provided sizes for

the specified devices.

It is important to note that MEMORY_TARGET and MEMORY_MAX_TARGET parameters should be

configured independently of DB_FLASH_CACHE_SIZE. They control the Oracle memory management

for the SGA and PGA, and do not directly correlate with the flash cache configuration.

Reference

Oracle Database 19c Documentation on Database Smart Flash Cache

Oracle Support Articles and Community Discussions on DB_FLASH_CACHE_SIZE Configuration

When an ORA-00060 deadlock error occurs, detailed information about the error and the deadlock

graph are dumped into the alert log. This log contains a trace file name that you can use to find

additional detailed information about the sessions involved in the deadlock and the SQL statements

they

were

executing.

Reference:

Oracle Database Administrator’s Guide, 19c

Oracle Database Error Messages, 19c

The DBMS_STATS.GATHER_DATABASE_STATS procedure is used to gather statistics for all schema

objects in the database that do not have up-to-date statistics. These statistics are essential for the

optimizer to make informed decisions about the most efficient way to execute a query. The

procedure collects statistics such as table and column statistics, index statistics, and system statistics,

which are all used in the execution plan generation.

Reference:

Oracle Database PL/SQL Packages and Types Reference, 19c

Oracle Database Performance Tuning Guide, 19c

The optimizer_adaptive_statistics parameter, when set to TRUE, enables the optimizer to use

adaptive statistics, such as SQL Plan Directives, to help improve plans by automatically adjusting

them based on the actual execution statistics.

Reference:

Oracle Database SQL Tuning Guide, 19c

The

DBMS_WORKLOAD_REPOSITORY.MODIFY_SNAPSHOT_SETTINGS

procedure

allows

setting

attributes related to AWR snapshots. While the interval setting controls the frequency of snapshot

generation, purging them is a separate process that can be managed either automatically (with

retention

settings)

or

manually.

Reference:

Oracle Database PL/SQL Packages and Types Reference, 19c

Oracle Multitenant Administrator’s Guide, 19c