In Oracle Database 18C very popular popular procedure DBMS_LOCK.SLEEP is also available in package DBMS_SESSION.Continue reading
In 18C release optimizer parameter OPTIMIZER_IGNORE_HINTS(was underscore parameter) is now documented.
If set to TRUE the optimizer ignores embedded hints. Can be changed on system or session level.
This article presents how to install Oracle 18C on Oracle Enterprise Linux 7 (OEL7) in silent mode.
In Oracle Database 18C type initialization is simplified with qualified expressions for Record type and Associative Array Type. It can help simplify coding.
rec_var := (field_name => some_value, .., field_name => some_value)
rec_var := (1 => some_value, .., 10 => some_value)
New type of temporary tables appeared in 18C called Private Temporary Tables. They are temporary database objects that are dropped at the end of a transaction or session. Private temporary tables are stored in memory and each one is visible only to the session that created it.
CREATE PRIVATE TEMPORARY TABLE .... ON COMMIT DROP DEFINITION or CREATE PRIVATE TEMPORARY TABLE .... ON COMMIT PRESERVE DEFINITION
||This creates a private temporary table that is transaction specific. All data in the table is lost, and the table is dropped at the end of transaction.|
||This creates a private temporary table that is session specific. All data in the table is lost, and the table is dropped at the end of the session that created the table.|
New type of schema can be created in 18C where user has no password.
CREATE USER username NO AUTHENTICATION;
Sequence is commonly known oracle object that is used to generate numbers in specified orders. In Oracle 18C new extra words can be defined for sequence creation:
- SCALE | NOSCALE(default)
- EXTEND | NOEXTEND(default)
In latest version of database 18C instead of killing user session you can cancel its currently running or opened SQL statement using the ALTER SYSTEM CANCEL SQL statement. Continue reading
Following article shows how to catch all ORA- statements in sqlplus using clause
SET ERRORLOGGING ON
General rule for creating indexes in Oracle is following:
- Bitmap indexes – always index nulls
- B*Tree cluster indexes – always indexes nulls
- B*Tree indexes – can’t index data if all indexed columns are NULL
The last one can cause some performance issues but there is trick to index all NULL columns also for B*Tree indexes.