Oracle Database 12c

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. Read More

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 Read More

ORACLE 12C : Advanced Index compression

Oracle 12c rel.1 ( introduced a new method for index compression called “advanced index compression” which is more effective in index compression than available methods in Oracle 11g . Creating an index using advanced index compression reduces the size of unique and non-unique indexes. Advanced index compression improves the compression ratios significantly . Advanced Index Compression is not supported for bitmap indexes and for indexes on unique single-column indexes. For a partitioned index, you can specify the compression type on a partition . You can also specify advanced index compression on index partitions even when the parent index is not Read More

Create Oracle Database 12c

Below are described installation step of Oracle Database Database 12c on Oracle Enterprise Linux 6. New Pluggable Database Features is chosen below. Install_Oracle_database12c