Interpretation of differences between Oracle11g and Oracle12c versions

Oracle database has always been one of the leaders in enterprise-level database management systems, and its continuously updated and iterative versions have also attracted widespread attention. Among them, Oracle 11g and Oracle 12c are two relatively representative versions, with many differences. This article will explain some important differences between Oracle 11g and Oracle 12c, and attach specific code examples to help readers gain a deeper understanding of the differences between the two versions.

1. Architecture differences

The architecture of Oracle 11g is based on the traditional single instance architecture, including an instance and a database. The instance is composed of background processes and memory structures. Oracle 12c introduces a multi-tenant architecture that supports multiple tenants sharing the same database instance, and each tenant has its own independent data and applications.

Example:

-- 创建一个多租户容器数据库
CREATE PLUGGABLE DATABASE pdb1 ADMIN USER adm1 IDENTIFIED BY password1
  ROLES = (dba)
  FILE_NAME_CONVERT = ('/pdbseed/', '/pdb1/');

-- 添加一个租户到容器数据库
CREATE PLUGGABLE DATABASE pdb2 ADMIN USER adm2 IDENTIFIED BY password2
  ROLES = (dba)
  FILE_NAME_CONVERT= ('/pdbseed/', '/pdb2/');

-- 移除一个租户
DROP PLUGGABLE DATABASE pdb2 INCLUDING DATAFILES;

2. Storage management differences

Oracle 12c introduces new storage management features, such as Automatic Data Optimization (ADO) and Heat Map, which can automatically manage Data storage and access. At the same time, Oracle 12c also supports various types of table spaces, such as In-Memory table spaces, Encrypted table spaces, etc.

Example:

-- 创建一个In-Memory表空间
CREATE TABLESPACE imts1
  DATAFILE '/u02/oradata/imts1_01.dbf' SIZE 100M
  INMEMORY
  MEMSTORE LOCAL;

-- 创建一个Encrypted表空间
CREATE ENCRYPTED TABLESPACE enc_ts
  DATAFILE '/u02/oradata/enc_ts01.dbf' SIZE 50M AUTOEXTEND ON NEXT 10M;

3. Performance optimization differences

Oracle 12c has many new features in performance optimization, such as SQL Plan Directives and Adaptive Execution Plans, which can improve SQL queries performance and stability. In addition, in terms of index management, Oracle 12c also added new index types, such as Invisible Indexes and Partial Indexes.

Example:

-- 创建一个Invisible Index
CREATE INDEX emp_idx ON employees (employee_id) INVISIBLE;

-- 创建一个Partial Index
CREATE INDEX emp_name_idx ON employees (last_name) WHERE department_id=10;

To sum up, Oracle 11g and Oracle 12c have obvious differences in architecture, storage management and performance optimization. By comparing the features of these two versions, you can better choose the version that suits your business needs and make full use of the functions it provides to improve database management efficiency and performance.

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