sql 监控

今天在使用GC的时候发现有一个 sql 监视的 功能，但是不知道什么意思，百度了一下，下面是博文连接：
http://blog.csdn.net/zengmuansha/article/details/23296613


Oracle 11g实时SQL监控：

前面提到，在Oracle Database 11g中，v$session视图增加了一些新的字段，这其中包括SQL_EXEC_START和SQL_EXEC_ID，这两个字段实际上代表了Oracle 11g的一个新特性：实时的SQL监控（Real Time SQL Monitoring）。

在Oracle 11g之前的版本，长时间运行的SQL可以通过监控v$session_longops来观察，当某个操作执行时间超过6秒，就会被记录在v$session_longops中，通常可以监控到全表扫描、全索引扫描、哈希联接、并行查询等操作；而在Oracle 11g中，当SQL并行执行时，会立即被实时监控到，或者当SQL单进程运行时，如果消耗超过5秒的CPU或I/O时间，它也会被监控到。监控数据被记录在v$sql_monitor视图中，当然也可以通过Oracle
11g新增的package DBMS_MONITOR来主动对SQL执行监控部署。

来看一下主要视图v$sql_monitor的结构：

sys@CCDB> desc v$sql_monitor

Name Null? Type

------------------------ -------- ------------------

KEY NUMBER

STATUS VARCHAR2(19)

FIRST_REFRESH_TIME DATE

LAST_REFRESH_TIME DATE

REFRESH_COUNT NUMBER

SID NUMBER

PROCESS_NAME VARCHAR2(5)

SQL_ID VARCHAR2(13)

SQL_EXEC_START DATE

SQL_EXEC_ID NUMBER

SQL_PLAN_HASH_VALUE NUMBER

SQL_CHILD_ADDRESS RAW(8)

SESSION_SERIAL# NUMBER

PX_SERVER# NUMBER

PX_SERVER_GROUP NUMBER

PX_SERVER_SET NUMBER

PX_QCINST_ID NUMBER

PX_QCSID NUMBER

ELAPSED_TIME NUMBER

CPU_TIME NUMBER

FETCHES NUMBER

BUFFER_GETS NUMBER

DISK_READS NUMBER

DIRECT_WRITES NUMBER

APPLICATION_WAIT_TIME NUMBER

CONCURRENCY_WAIT_TIME NUMBER

CLUSTER_WAIT_TIME NUMBER

USER_IO_WAIT_TIME NUMBER

PLSQL_EXEC_TIME NUMBER

JAVA_EXEC_TIME NUMBER

注意这里的SQL_EXEC_ID就是v$session视图中新增字段的来源。这个视图还记录了SQL的CPU_TIME以及BUFFER_GETS等重要信息，对于诊断SQL性能问题具有极大的帮助。结合v$sql_monitor视图与v$sql_plan_monitor视图可以进一步查询SQL的执行计划等信息。联合一些其他视图，如v$active_session_history、v$session、v$session_longops、v$sql、v$sql_plan等，可以获得关于SQL的更多信息。

v$sql_monitor收集的信息每秒刷新一次，接近实时，当SQL执行完毕，信息并不会立即从v$sql_monitor中删除，至少会保留1分钟，v$sql_plan_monitor视图中的执行计划信息也是每秒更新一次，当SQL执行完毕，它们同样至少被保留1分钟。

实时SQL监控需要statistics_level初始化参数设置为TYPICAL或ALL：

sys@CCDB> show parameter statistics_level

NAME TYPE VALUE

--------------------- ------------ -------------

statistics_level string TYPICAL

sys@CCDB> select statistics_name,session_status,system_status,activation_level,session_settable

2 from v$statistics_level

3 where statistics_name = 'SQL Monitoring';

STATISTICS_NAME SESSION_STATUS SYSTEM_STATUS ACTIVATION_LEVEL SESSION_S

----------------- ---------------- ---------------- ------------------ ---------

SQL Monitoring ENABLED ENABLED TYPICAL YES

同时CONTROL_MANAGEMENT_PACK_ACCESS参数必须是DIAGNOSTIC+TUNING（这是缺省设置）：

sys@CCDB> show parameter control_manage

NAME TYPE VALUE

------------------------------------ ------------ ----------------------

control_management_pack_access string DIAGNOSTIC+TUNING

在如上设置下，数据库会启动自动的实时SQL监控，Oracle还提供Hints可以强制制定对SQL执行监控或者不允许监控，这两个Hints是monitor与no_monitor。

强制对某个SQL使用实时监控可以如下改写SQL：

select /*+ monitor */ count(*) from emp where sal > 5000;

指定不执行实时监控：

select /*+ no_monitor */ count(*) from emp where sal > 5000;

查看数据库中已经生成的监控信息可以使用DBMS_SQLTUNE包来实现：

sys@CCDB> set long 10000000

sys@CCDB> set longchunksize 10000000

sys@CCDB> set linesize 200

sys@CCDB> select dbms_sqltune.report_sql_monitor from dual;

REPORT_SQL_MONITOR

-----------------------------------

SQL Monitoring Report
SQL Text

--------------------------------------------------------------

--------------------------------------------------------------
Global Information

Status : DONE (ALL ROWS)

Instance ID : 1

Session ID : 982

SQL ID : gn3h2qrqdfwru

SQL Execution ID : 16777216

Plan Hash Value : 2959114426

Execution Started : 02/28/2010 14:02:37

First Refresh Time : 02/28/2010 14:02:41

Last Refresh Time : 02/28/2010 14:02:42
--------------------------------------------------------------------

| Elapsed | Cpu | IO | Other | Fetch | Buffer | Reads |

| Time(s) | Time(s) | Waits(s) | Waits(s) | Calls | Gets | |

--------------------------------------------------------------------

| 3.46 | 0.13 | 2.38 | 0.94 | 1 | 1752 | 1214 |

--------------------------------------------------------------------
SQL Plan Monitoring Details

============================================================================================================================================

| Id | Operation | Name | Rows | Cost | Time | Start | Starts | Rows | Activity | Activity Detail |

| | | | (Estim) | | Active(s) | Active | | (Actual) | (percent) | (sample #) |

============================================================================================================================================

| 0 | SELECT STATEMENT | | | | 1 | +5 | 1 | 1 | | |

| 1 | SORT AGGREGATE | | | | 1 | +5 | 1 | 1 | | |

| 2 | APPROXIMATE NDV AGGREGATE | | | | 2 | +4 | 1 | 58610 | | |
REPORT_SQL_MONITOR

--------------------------------------------------------------------------------------------------------------------------------------------------

| 3 | TABLE ACCESS FULL | | | | 5 | +1 | 1 | 86645 | 100.00 | Cpu (1) |

| | | | | | | | | | | db file scattered read (3) |

=======================================================================================================================

我在自己的RAC测试机测了下 果真不错 只是设置SET LINESIZE 1000 然后把字体调小到9号 SSH CLIENT 就很好显示执行计划了
SQL Monitoring Report

SQL Text

------------------------------

SELECT SUM(C) FROM ( SELECT COUNT(*)C FROM CCPS_TRADERECORD T,CCPS_CREDITINFO C WHERE 1=1 AND t.tr_no=C.CI_TR_NO AND T.TR_STATUS=1 AND CI_SHA256=:1 UNION SELECT COUNT(*) C FROM CCPS_OLDWHITELIST OW WHERE OW.OW_CARDINFO=:2 )

Global Information

------------------------------

Status : DONE (ALL ROWS)

Instance ID : 2

Session : ASIACASH (47:12925)

SQL ID : 52ukfnr2ns742

SQL Execution ID : 33554456

Execution Started : 04/09/2014 12:29:33

First Refresh Time : 04/09/2014 12:29:37

Last Refresh Time : 04/09/2014 12:30:16

Duration : 43s

Module/Action : JDBC Thin Client/-

Service : lotest

Program : JDBC Thin Client

Fetch Calls : 1

Binds

========================================================================================================================

| Name | Position | Type | Value |

========================================================================================================================

| :1 | 1 | VARCHAR2(4000) | 12a37ad2972ba2ad58fa834ce69aeb489e3e6824a3fcbba078146b2cfe619bc0b41627f0a4e6cbcc6 |

| | | | cbf401610e4c3ee1b21b3a695ec1146749027aa2fc96774796788528826034928717be5efd3da6e |

| :2 | 2 | VARCHAR2(4000) | d22c0b383ff28ab45e15694f4b949b2a598ec8a18400c3dab33f1f2e02be0ed0 |

========================================================================================================================

Global Stats

============================================================================

| Elapsed | Cpu | IO | Cluster | Fetch | Buffer | Read | Read |

| Time(s) | Time(s) | Waits(s) | Waits(s) | Calls | Gets | Reqs | Bytes |

============================================================================

| 45 | 8.06 | 27 | 11 | 1 | 64447 | 43843 | 353MB |

============================================================================

SQL Plan Monitoring Details (Plan Hash Value=3401659647)

==========================================================================================================================================================================================

| Id | Operation | Name | Rows | Cost | Time | Start | Execs | Rows | Read | Read | Mem | Activity | Activity Detail |

| | | | (Estim) | | Active(s) | Active | | (Actual) | Reqs | Bytes | (Max) | (%) | (# samples) |

==========================================================================================================================================================================================

| 0 | SELECT STATEMENT | | | | 1 | +43 | 1 | 1 | | | | | |

| 1 | SORT AGGREGATE | | 1 | | 1 | +43 | 1 | 1 | | | | | |

| 2 | VIEW | | 2 | 6764 | 1 | +43 | 1 | 2 | | | | | |

| 3 | SORT UNIQUE | | 2 | 6764 | 1 | +43 | 1 | 2 | | | 2048 | | |

| 4 | UNION-ALL | | | | 1 | +43 | 1 | 2 | | | | | |

| 5 | SORT AGGREGATE | | 1 | 6761 | 2 | +42 | 1 | 1 | | | | | |

| 6 | HASH JOIN | | 3470 | 6457 | 40 | +4 | 1 | 200K | | | 21M | 2.38 | Cpu (1) |

| 7 | TABLE ACCESS BY INDEX ROWID | CCPS_CREDITINFO | 3469 | 866 | 41 | +2 | 1 | 203K | 32298 | 252MB | | 76.19 | gc cr grant 2-way (10) |

| | | | | | | | | | | | | | Cpu (8) |

| | | | | | | | | | | | | | db file sequential read (14) |

| 8 | INDEX RANGE SCAN | IX_CI_SHA256 | 3417 | 166 | 42 | +1 | 1 | 203K | 9193 | 72MB | | 21.43 | gc cr grant 2-way (3) |

| | | | | | | | | | | | | | Cpu (2) |

| | | | | | | | | | | | | | db file sequential read (4) |

| 9 | TABLE ACCESS FULL | CCPS_TRADERECORD | 201K | 5590 | 2 | +42 | 1 | 201K | 124 | 11MB | | | |

| 10 | SORT AGGREGATE | | 1 | 3 | 1 | +43 | 1 | 1 | | | | | |

| 11 | INDEX UNIQUE SCAN | OW_CARDINFO | 1 | 2 | | | 1 | | 3 | 24576 | | | |

=======================================================================================================================================