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Archive for the ‘12cR2 New features’ Category

12cR2 feature # 5 – HISTORY in sqlplus prompt

Posted by Pavan DBA on December 17, 2016


12cR2 has introduced new option HISTORY in sqlplus to view or edit or delete the sql, pl/sql commands we have executed in SQL prompt. This works just like “history” command in Unix prompt.

SQL> set history on –> enables the history

SQL> set history off –> disables the history

SQL> show history –> to check if history is ON or OFF

example:

SQL> set history ON

SQL> select count(*) from emp;

SQL> desc dept

SQL> select name from v$database;

SQL> history
1 select count(*) from emp;
2 desc dept
*  3 select name from v$database; (* represents last used command)

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12cR2 feature # 4 – table & column name length

Posted by Pavan DBA on December 14, 2016


From 12cR2, table and column name length can be upto 128 characters instead of previous limitation to 30 characters.

But it is having following limitations still

Database name still will be 8 character long
tablespace name, pluggable database name, disk group name is 30 characters

 

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12cR2 feature # 3 – parameters default value change

Posted by Pavan DBA on December 12, 2016


Some parameters default value has been changed in 12cR2 as follows

OPTIMIZER_ADAPTIVE_PLANS controls adaptive plans. It is now set by default to FALSE. Adaptive plans is the alternative execution plans which will be decided during query executions.

OPTIMIZER_ADAPTIVE_STATISTICS controls adaptive statistics. It is set by default to FALSE.

SQL92_SECURITY Default is TRUE

If a user want to perform DELETE or UPDATE on an object, it should have SELECT privilege as mandatory from now onwards.

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12cR2 feature #2 – desupported parameters

Posted by Pavan DBA on December 9, 2016


In this post we will see what are all the parameters that are desupported since 12cR2.

GLOBAL_CONTEXT_POOL_SIZE

This parameter used to allocate memory in SGA for storing and managing global application context

MAX_ENABLED_ROLES

It specifies max no of roles that can be enabled by a user

OPTIMIZER_ADAPTIVE_FEATURES

This has been split into two new parameters.

OPTIMIZER_ADAPTIVE_PLANS=TRUE which determines alternative execution plans
OPTIMIZER_ADAPTIVE_STATISTICS=FALSE which determines alternative plan directives

PARALLEL_AUTOMATIC_TUNING

It provides default value for controlling parallel processing

PARALLEL_IO_CAP_ENABLED

It is replaced with PARALLEL_DEGREE_LIMIT to spcify default degree of parallellism

PARALLEL_SERVER

It is to start database in parallel server mode. It is replaced by CLUSTER_DATABASE

PARALLEL_SERVER_INSTANCES

It specify no of instances configured in cluster database environment and is replaced by CLUSTER_DATABASE_INSTANCES

USE_INDIRECT_DATA_BUFFERS

The parameter was used to enable the Very Large Memory feature for 32-bit platforms. These platforms are no longer supported.

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12cR2 feature # 1 – deprecated parameters

Posted by Pavan DBA on December 8, 2016


Hey friends, as many of you already know that Oracle database 12c Release 2 documentation is officially available now in Oracle site. Thought of sharing some new features through some posts.

When software is available, I will share the practical demos on these new features.

12cR2 feature # 1 –

Following init parameters are deprecated

O7_DICTIONARY_ACCESSIBILITY

This parameter prevents any schema to access SYS schema objects.

ASM_PREFERRED_READ_FAILURE_GROUPS

In 12cR2 ASM, specifying the preferred read failure groups is done automatically. We need to use the PREFERRED_READ.ENABLED disk group attribute to control the preferred read functionality.

PARALLEL_ADAPTIVE_MULTI_USER 

This specifies the use of adaptive algorithm to improve performance in multi-user environments that use parallel execution. We need to use Database feature parallel statement queuing instead of this parameter.

UTL_FILE_DIR

Oracle recommends to use DIRECTORY feature instead of this parameter.

 

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