我想大家都可能有一个疑问,数据库从以前版本升级到12C,计划使用in-memory特性,那我怎么评估哪些表放进去合适,放进去后,整体性能又会提升多少,需要in-memory内存为多大？这些问题如果人工去判断不一定准确,而且可能有很多遗落,Oracle也考虑到了这一点,因此发布了Oracle Database InMemory Advisor,从而来比较简单的实现数据库使用In-Memory简单配置.Oracle Database InMemory Advisor主要通过DBMS_INMEMORY_ADVISOR包分析 Active Session History (ASH), Automatic Workload Repository (AWR) and SQL Tuning Sets (STS)信息进行分析,给出建议.

Oracle Database InMemory Advisor使用前提
1.数据库版本为11.2.0.3及其以上版本(compatibility>=11.2.0.3)
2.需要有Database Tuning pack liscense支持(仅仅是liscense,不是功能)

安装Oracle Database InMemory Advisor

[oracle@localhost xff]$ unzip imadvisor.zip
Archive:  imadvisor.zip
  inflating: instimadv.sql
  inflating: dbmsimadv.sql
  inflating: prvtimadv.plb
  inflating: dbmsimadvint.plb
  inflating: prvtimadvint.plb
  inflating: schmimadv.sql
  inflating: imadvisor_version.sql
  inflating: imadvisor_load_report_templates.sql
  inflating: imadvisor_clone_view.sql
  inflating: imadvisor_analyze_and_report.sql
  inflating: imadvisor_spool_debug.sql
  inflating: imadvisor_export.sql
  inflating: imadvisor_DataPump.sql
  inflating: imadvisor_awr_augment_export.sql
  inflating: imadvisor_awr_augment_import.sql
  inflating: imadvisor_awr_augment_tables.sql
  inflating: imadvisor_fetch_recommendations.sql
[oracle@localhost xff]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Wed Mar 18 16:21:08 2015
Copyright (c) 1982, 2013, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> @instimadv
Welcome to the Oracle Database In-Memory Advisor (DBMS_INMEMORY_ADVISOR)
installation.
The Oracle Database In-Memory Advisor is licensed as part of the Oracle Tuning Pack.
Do you currently have a valid Oracle Tuning Pack license with this database (Y/N)? Y
DBMS_INMEMORY_ADVISOR uses Active Session History (ASH), Automatic Workload
Repository (AWR) and optionally SQL Tuning Sets (STS) to determine which
tables, partitions and subpartitions to place In Memory for optimized analytics
processing performance.  DBMS_INMEMORY_ADVISOR produces a recommendation report
and a SQLPlus script to implement its recommendations.
This installation script will create user IMADVISOR and add object
definitions to the schema including the DBMS_INMEMORY_ADVISOR package.  This
installation script creates user IMADVISOR using the
IDENTIFIED BY password method. If you prefer to use either the
IDENTIFIED EXTERNALLY or IDENTIFIED GLOBALLY method, abort this installation
by pressing ^C. Then create user IMADVISOR using your preferred
method.  Add no objects to the IMADVISOR schema.  Then run this
installation script again.
These actions will be taken on the database to which you are currently
connected.
Please enter the connection ID for the current database?
qsng
This installation script creates a new Oracle database user and schema
named IMADVISOR for the operation of DBMS_INMEMORY_ADVISOR...
Please enter the password for user IMADVISOR?
For confirmation, please re-enter the password for user IMADVISOR?
Available tablespaces:
TABLESPACE_NAME
------------------------------
FSDATA
MYDATA
SYSAUX
SYSTEM
TEMP
UNDOTBS1
USERS
Please enter the default tablespace name for user IMADVISOR?
users
The In-Memory Advisor uses the Oracle directory object IMADVISOR_DIRECTORY
by default.
If you wish to create the IMADVISOR_DIRECTORY object, please enter an OS host
directory path for the IMADVISOR_DIRECTORY object.
If not, please press ENTER to continue.
? /tmp/xff
Connecting to IMADVISOR @ qsng..
Enter password:
Connected.
No errors.
No errors.
No errors.
No errors.
No errors.
No errors.
DBMS_INMEMORY_ADVISOR installation successful.
Users who will use the DBMS_INMEMORY_ADVISOR package must be GRANTed
EXECUTE on the DBMS_INMEMORY_ADVISOR package.
Please enter a comma separated list of Oracle Database users to whom
you wish EXECUTE on the DBMS_INMEMORY_ADVISOR package to be GRANTed?
SYS
GRANT EXECUTE ON dbms_inmemory_advisor TO SYS
While logged in as IMADVISOR or with sufficient privileges, you can
GRANT EXECUTE ON DBMS_INMEMORY_ADVISOR to additional users as needed.
DBMS_INMEMORY_ADVISOR installation and setup complete.
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

Oracle Database InMemory Advisor生成报告

[oracle@localhost xff]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Wed Mar 18 16:30:57 2015
Copyright (c) 1982, 2013, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> @imadvisor_analyze_and_report
Specify the IM task name
The IM Advisor generates a report as  imadvisor_<taskname>.html file
in the current working directory
The sql file is generated as imadvisor_sql_<taskname>.sql
Enter value for im_task_name: xifenfei
IM Task name Specified: xifenfei
Enter begin time for report:
--    Valid input formats:
--      To specify absolute begin time:
--        [MM/DD[/YY]] HH24:MI[:SS]
--        Examples: 02/23/03 14:30:15
--                  02/23 14:30:15
--                  14:30:15
--                  14:30
--      To specify relative begin time: (start with '-' sign)
--        -[HH24:]MI
--        Examples: -1:15  (SYSDATE - 1 Hr 15 Mins)
--                  -25    (SYSDATE - 25 Mins)
Enter value for begin_time: -3
Report begin time specified: -3
old 102:   lbtime_in  := nvl('&&begin_time', '-60');
new 102:   lbtime_in  := nvl('-3', '-60');
old 104:   :btime := to_char( begin_time, '&&imadvisor_time_format' );
new 104:   :btime := to_char( begin_time, 'YYYY-MON-DD HH24:MI:SS.FF' );
Enter duration in minutes starting from begin time:
Defaults to SYSDATE - begin_time
Enter value for duration:
Report duration specified:
old   8:   begin_time := to_timestamp(:btime, '&&imadvisor_time_format');
new   8:   begin_time := to_timestamp(:btime, 'YYYY-MON-DD HH24:MI:SS.FF');
old  18:   duration   := nvl('&&duration', since_begin_time);
new  18:   duration   := nvl('', since_begin_time);
old  29:   :etime := to_char( end_time, '&&imadvisor_time_format' );
new  29:   :etime := to_char( end_time, 'YYYY-MON-DD HH24:MI:SS.FF' );
Using 2015-MAR-18 16:28:22.000000000 as report begin time
Using 2015-MAR-18 16:31:22.000000000 as report end time
IM Advisor: Adding Statistics..
IMADVISOR: Finished Adding Statistics
IMADVISOR: Finished Executing the task
IM Advisor: Generating Recommendations..
imadvisor_xifenfei.html
imadvisor_sql_xifenfei.html
imadvisor_object_xifenfei.html
imadvisor_xifenfei.sql
'Fetching recommendation files for task xifenfei'
IM Advisor generated report in imadvisor_xifenfei.html
IM Advisor genreated DDL script in imadvisor_xifenfei.sql
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@localhost xff]$ ls -ltr *xifenfei*
-rw-r--r-- 1 oracle oinstall   887 Mar 18 16:33 imadvisor_xifenfei.sql
-rw-r--r-- 1 oracle oinstall 30175 Mar 18 16:33 imadvisor_xifenfei.html
-rw-r--r-- 1 oracle oinstall 13576 Mar 18 16:33 imadvisor_sql_xifenfei.html
-rw-r--r-- 1 oracle oinstall  8931 Mar 18 16:33 imadvisor_object_xifenfei.html
-rw-r--r-- 1 oracle oinstall  3405 Mar 18 16:33 imadvisor_auxiliary_xifenfei.html

这里输入的Task name为:xifenfei,Oracle Database InMemory Advisor结果
imadvisor_xifenfei.html是InMemory Advisor的一个整体描述
imadvisor_xifenfei.sql是InMemory Advisor生成的表级别的INMEMORY语句,可以直接通过@方式执行,或者修改后执行
imadvisor_sql_xifenfei.html主要是InMemory Advisor中关于sql的分析报告
imadvisor_object_xifenfei.html是InMemory Advisor中建议InMemory处理的对象分析报告
imadvisor_auxiliary_xifenfei.html 是一个辅助的总结

卸载Oracle Database InMemory Advisor

[oracle@localhost ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Wed Mar 18 21:55:49 2015
Copyright (c) 1982, 2013, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> drop user imadvisor cascade;
User dropped.

补充内容
1.在某些情况下,可能无法直接创建用户imadvisor,或者创建目录imadvisor_directory,可以通过类似命令创建,并修改instimadv.sql脚本屏蔽掉交互式安装

create user IMADVISOR identified by Oracle_123 DEFAULT TABLESPACE system;
CREATE OR REPLACE DIRECTORY imadvisor_directory AS '/tmp/xff/txt';
GRANT READ, WRITE ON DIRECTORY imadvisor_directory TO IMADVISOR;

2.在执行@imadvisor_analyze_and_report生成报告,可能会遇到ORA-24817: Unable to allocate the given chunk for current lob operation,解决方案为：

1. Copy the original script to a new location to serve as a backup.
2. Edit the script imadvisor_fetch_recommendations.sql and change the line in the script:
SET LONGCHUNKSIZE 2000000000
to
SET LONGCHUNKSIZE 32767
3. Save and run the script.

参考文档
Oracle Database InMemory Advisor (Doc ID 1965343.1)
Using Inmemory Advisor Errors When Running Imadvisor_analyze_and_report (Doc ID 1987462.1)