Category: Oracle Database 12 c

ORACLE 12C : Listener service registration

With previous releases PMON (Process Monitor) was responsible for registering database services to the Listener. Starting from Oracle 12C there is a change in architecture with respect to the service registration in Oracle Database Release 12c. Oracle has introduced a new mandatory background process dedicated for “database service registration to the Listener” and named LREG (Listener Registration Process). The listener registration process (LREG) registers information about the database instance and dispatcher processes with the Oracle Net listener (see “The Oracle Net Listener”). When an instance starts, LREG polls the listener to determine whether it is running. If the listener is running,...

ORACLE 12C: Dataguard Far Sync

Oracle Dataguard Far Sync instance is a new feature introduced in Oracle Database 12c, which simply works like a archive/redo repeater.. Far sync instance is something different than the Oracle Database instance, as its mission is accepting redo from the primary database and then shipping that redo to other members of the Oracle Data Guard configuration.. Far Sync instance is an instance without a database.. Although; it has controlfile, and capability to read from standby redolog files and write them into its local archive log files, Far Sync instance does not map any database file, in other words, does not...

Create Sequence-Oracle Database 12c

Database version : from Oracle Database 12cR1 Create sequence with session or global option When a sequence number is generated, the sequence is incremented, independent of the transaction committing or rolling back. SESSION option makes opportunity to create sequence that can used in association with global temporary table then its visibility is just for session. The following options CACHE, NOCACHE, ORDER, or NOORDER are ignored when SESSION is declared. 1) statement SQL> CREATE GLOBAL TEMPORARY TABLE glb_tmp_table (a number); Table created. SQL> CREATE SEQUENCE sq_sess SESSION; Sequence created. 2) Script execution SQL> INSERT INTO glb_tmp_table VALUES (sq_sess.NEXTVAL); 1 row created....

ORACLE 12 rel.2 – Partitioning new features

In Oracle 12c rel.2 a great number of enhancements to the Oracle database Partitioning option have been introduced. These include: Automatic List Partitioning Filtered Partition maintenance operations Multi-Column List Partitioning Online conversion of non-partitioned to partitioned table Read-only Partitions Partitioned External Tables Automatic List Partitioning: The ability to partition a table based on distinct values in a column has been around since quite some time, but what is new in Oracle database 12.2 is that we can initially partition the table based on values that are known and present in the column we would like to partition the table on....

ORACLE 12C M.T.S. model

Until Oracle Database 12c, Oracle processes did not run as threads on UNIX and Linux systems. Every dedicated connection was represented by an operating system process. In systems where high workload was an issue, the only way to reduce CPU and memory usage was to switch from dedicated connections to shared connections using the multithreaded server (MTS) feature. Starting in Oracle Database 12c the multithreaded database model was introduced, enabling database processes to be executed as operating system threads and reducing the number of dedicated process necessary to manage database services. By default, every new 12c instance is created to...

Memory Resource Management for PDBs in Oracle Database 12c Rel.2 (12.2)

In the previous release there was no way to control the amount of memory used by an individual PDB. It could use up lots of memory and impact the performance of other PDBs in the same instance. Oracle Database 12c Rel.2 (12.2) allows to control the amount of memory used by a PDB. PDB Memory Parameters The following parameters can be set at the PDB level. DB_CACHE_SIZE : minimum buffer cache size for the PDB. SHARED_POOL_SIZE : minimum shared pool size for the PDB. PGA_AGGREGATE_LIMIT : maximum PGA size for the PDB. PGA_AGGREGATE_TARGET : target PGA size for the PDB....

Oracle12C : Database Firewall

The Oracle Database Firewall enables organizations to protect their databases from internal and external attacks. Oracle Database Firewall allows unauthorised SQL traffic on the network to be monitored and blocked before reaching the database. Database Firewall for Security and Compliance Oracle Database Firewall monitors and enforces normal application behavior in order to avoid the increasingly sophisticated Data Centre attacks that can lead to unauthorised external access. The security control of Oracle Database Firewall helps to prevent malicious activity such as SQL injection and application bypass from reaching the database. Next-Generation Network-based Database Security The grammar of the SQL statements being...

ORACLE 12C: Data Migration Assistant

The Database Migration Assistant for Unicode (DMU) provides a good solution for migrating databases from legacy character sets to the Unicode character set. It is shipping with Oracle Database 12c Rel.1 and becomes the officially supported method for migration to the Unicode character set. Database Character Set Scanner (CSSCAN) and CSALTER utilities are removed from the database installation and have been desupported. DMU also supports migrating selected prior database releases of 10.2, 11.1 and 11.2. Oracle DMU 2.1, released in May 2015, supports a near-zero downtime migration model in conjunction with the Oracle GoldenGate replication technology. Using DMU2.1 and GoldenGate...

ORACLE 12C : Extended Data Type

With the previous Oracle database release, long characters strings of more then 4000 bytes had to be handled using CLOB or LONG data types. Starting from Oracle 12c was introduced a new system parameter: MAX_STRING_SIZE. This parameter allows string data types to be much larger when the parameter is changed from its default value STANDARD to EXTENDED. New higher limits (in bytes) are available for following types: – VARCHAR2 – 32767 bytes – NVARCHAR – 32767 bytes – RAW – 32767 bytes To use extended version you need to set new initialization parameter MAX_STRING_SIZE and run sql script utl32k.sql. Set...

Oracle 12C Last Login Time

In the previous releases, to be able to know the last login time of the user, we had to enable “AUDIT SESSION” and then query the AUD$ table. The SYS.USER$ table in Oracle Database 12c includes a column to store the last login time of the user. As part of the increased security features in 12c, last login time is now stored in the USER$ table itself, in SPARE6 column. This is great information to know when a user last used the database. Security related values in the USER$ table are : CTIME: Date & Time when user was created...