Category Archives: OCP FlashCards

OCP 12C – Oracle Data Redaction

What is Oracle Data Redaction ?

  • Oracle Data Redaction is meant to mask (redact) sensitive data returned from application queries.
  • Oracle Data Redaction doesn’t make change to data on disk, the sensitive data is redacted on the fly before it is returned to the application.
  • You can redact column data by using one of the following methods:
    • Full redaction. You redact all of the contents of the column data.
    • Partial redaction. You redact a portion of the column data.
    • Regular expressions. You can use regular expressions to look for patterns of data to redact.
    • Random redaction. The redacted data presented to the querying application user appears as randomly generated values each time it is displayed, depending on the data type of the column.
    • No redaction. The None redaction type option enables you to test the internal operation of your redaction policies, with no effect on the results of queries against tables with policies defined on them.

Data Redaction Continue reading OCP 12C – Oracle Data Redaction

OCP 12C – Resource Manager and Performance Enhancements

Use Resource Manager for a CDB and a PDB

Managing Resources between PDBs

  • The Resource Manager uses Shares ans Utilization limit to manage resources allocated to PDBs.
  • The more “Shares” you allocate to a PDB, the more resource it will have.
  • One directive can only concern one PDB and you can’t have multiple directive for the same PDB in the same plan.

Resource Manager

  • You can limit resource utilization of a specific PDB by using the UTILIZATION_LIMIT of the CREATE_CDB_PLAN_DIRECTIVE procedure. UTILIZATION_LIMIT is expressed in percentage of total system resources, if you set it to 50 it, the PDB will be able to use 50% of total system resources (CPU, I/O, parallel server).
  • The PARALLEL_SERVER_LIMIT parameter let you limit the parallel server utilization for a PDB.
  • If you don’t define a plan for a PDB, the default one applies, by default a PDB is being allocated :
    • 1 Share
    • No Utilization Limit
    • No Parallel Server Utilization limit

Continue reading OCP 12C – Resource Manager and Performance Enhancements

OCP 12C – SQL Enhancements

Extended Character Data Type Columns

  • In this release Oracle changed the maximum sixe of three data types
Data Type Old Maximum size New Maximum size
VARCHAR2 4000 bytes 32.767 bytes
NVARCHAR2 4000 bytes 32.767 bytes
RAW 2000 bytes 32.767 bytes
  •  In Oracle 12c if you set a VARCHAR2 to 4000 bytes or less it is stored inline, if you set it to more than 4000 bytes then it is transformed in extended character data type and stored out of line.
  • The new extended character data types are not enabled by default, you have to enable them explicitly using the following procedure:
SQL> conn / as sysdba
SQL> shutdown immediate
SQL> startup upgrade
SQL> alter system set max_string_size=extended;
SQL> @?/rdbms/admin/utl32k.sql
SQL> shutdown immediate
SQL> startup
  •  Be careful with the MAX_STRING_SIZE parameter, once changed from STANDARD to EXTENDED, you can’t go back to standard, it is irreversible.
  • Oracle recommends not to increase the size of existing varchar2 from their current size to 32,767 unless you have to, because it can cause row chaining. To modify a column it is recommended de recreate the table.
  • If you extend a column size, you’ll need to recreate the index too because it doesn’t support data type extensions.

Continue reading OCP 12C – SQL Enhancements