Thursday, August 28, 2014

Some 12C Features

Will try to describe some of the 12C features and will keep editing this post.

Note:
  • If you want to install Oracle 12 on Windows 7, refer the steps here 
  • To troubleshoot invalid common user or role name after installation, go here

Feature List

 Identity Columns:
  • Also known as auto-number column. This implies that the data in the column should increase when data is inserted).
  • Read article on the same here.

 Invisible Columns:
  • Columns can be made invisible
  • It gives one the ability to introduce a change while minimizing any negative side effects of that change.
  • Read article on the same here 
With Clause:
  • Instead of using a stored PL/SQL function, we can include the body of the function in the SQL query
  • Read article on the same here 
 Truncate statements with the cascade option
  • We could not truncate table with foreign key constraints.
  • Now in 12c, one can execute the truncate table command with the cascade option (to cascade through the child tables).
  • Note: You would need to create the foreign key with the "on delete cascade" option
Columns can have a default value in place of NULL
  • You can define a column to have a default value when NULL is inserted
  • e.g. create table ......  product_id NUMBER ON NULL 0,.....
  • So if one explicity inserts NULL, it will be populated by value 0
Multiple Index - same columns
  • You can create multiple indexes (different types) on a same set of columns.
  • Assume you need to change from B*tree to Bitmap or vice versa.
  • You need not drop the index.
  • Just make the first index invisible and make a new index.
  • Conditions:
    • Different types of indexes
    • Different uniqueness
    • Different partitions are used
 



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