Oracle Real Time SQL Monitor

Oracle Real Time SQL Monitor
Oracle数据库的实时SQL监控能让你用来监控正在执行SQL语句的性能。缺省情况下，当SQL语句使用 并行执行或当SQL语句的单个操作消耗了5秒的CPU或I/O时间就会自动启动SQL监控。可以使用v $sql_monitor与v$sql_plan_monitor视图来监控SQL语句执行的统计信息。可以使用这些视图时行关 联来获得被监控到的关于执行的其它信息:
.v$active_session_history
.v$session
.v$session_longops
.v$sql
.v$sql_plan

在监控初始化之后，数据库将会向动态性能视图v$sql_monitor中增加条目。这个条目跟踪SQL执行的 关键性能，包括：执行时间，CPU时间，读取与写入的次数，I/O等待时间和各种其它等待时间。这些 统计信息当SQL语句执行时间会被实时刷新，每秒生成一次。在执行结束后，监控信息不会立即被删 除，但在v$sql_monitor中至少保留一分钟。当需要为新的SQL语句腾出空间时，会评估条目是否需要 被删除来回收空间。

v$sql_monitor视图包含v$sql视图中统计信息的一组子集。然而，不像v$sql，监控统计信息不会对 多次执行进行累加。相反，v$sql_monitor中的一个条目被关联到SQL语句的一个单独操作。如果数据 库监控相同SQL语句执行两次，那么在v$sql_monitor中会有两次执行的统计信息。

为了唯一标识相同SQL语句的两次执行，会生成一个叫执行键的复合键。执行键是由三个属性组成， 它们分别为v$sql_monitor中的:
.SQL标识符用来标识SQL语句(SQL_ID)
.开始执行时间(SQL_EXEC_START)
.一个内部生成的标识符用来确保主键是唯一的(SQL_EXEC_ID)

SQL执行计划监控
真时SQL监控也包括监控SQL语句的执行计划中的每一个操作的统计信息。这些数据在v $sql_plan_monitor视图中可以看到。类似于v$sql_monitor视图，v$sql_plan_monitor视图中的统计 信息当SQL语句被执行时每秒会更新一次。这些统计信息在SQL执行结束后是存在的，它的生命周期与 v$sql_monitor是一样的。对于每个被监控的SQL语句，在v$sql_plan_monitor视图中将会有多个条目 ，每个条目关联执行计划中的一个操作。

并行执行监控
Oracle数据库会当SQL语句开始执行时会自动监控并行查询，DML与DDL语句。v$sql_monitor与v $sql_plan_monitor视图将会以单独的条目来记录并行执行中每个操作的监控信息。

v$sql_monitor对于并行执行协调进程和每个并行执行服务器进程有一个条目。对于每一个条目在v $sql_plan_monitor视图中也有相关的条目。因为对于SQL语句并行执行的所分配的进程是相互协作的 ，这些条目共享相同的执行键（由sql_id,sql_exec_start与sql_exec_id组成）。因此可以聚合执行 键来判断并行执行的整个统计信息。

生成SQL监控报告
可以使用SQL监控报告来查看SQL监控数据。SQL监控报告使用以下视图中的数据:
.gv$sql_monitor
.gv$sql_plan_monitor
.gv$sql
.gv$sql_plan
.gv$active_session_history
.gv$session_longops

为了生成SQL监控报告，运行dbms_sqltune.report_sql_monitor过程:

SQL> set long 10000000
SQL> set longchunksize 10000000
SQL> set linesize 200
SQL> variable my_rept clob;
SQL> begin
  2   :my_rept:=dbms_sqltune.report_sql_monitor();
  3  end;
  4  /
print :my_rept

PL/SQL procedure successfully completed.

SQL>
MY_REPT
---------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------- ------------------------
SQL Monitoring Report

SQL Text
------------------------------
/* SQL Analyze(1) */ select /*+ full(t) no_parallel(t) no_parallel_index(t) dbms_stats  cursor_sharing_exact use_weak_name_resl dynamic_sampling(0) no_monitoring no_substrb_pad  */to_char(count("AAE064"
)),to_char(substrb(dump(min("AAE064"),16,0,32),1,120)),to_char(substrb(dump(max ("AAE064"),16,0,32),1,120)),to_char(count("AAB001")),to_char(substrb(dump(min ("AAB001"),16,0,32),1,120)),to_char(substrb(
dump(max("AAB001"),16,0,32),1,120)),to_char(count("AAB191")),to_char(substrb(dump(min ("AAB191"),16,
0,32),1,120)),to_char(substrb(dump(max("AAB191"),16,0,32),1,120)),to_char(count ("AAB190")),to_char(substrb(dump(min("AAB190"),16,0,32),1,120)),to_char(substrb(dump (max("AAB190"),16,0,32),1,120)),to_ch
ar(count("AAB211")),to_char(substrb(dump(min("AAB211"),16,0,32),1,120)),to_char(substrb (dump(max("AAB211"),16,0,32),1,120)),to_char(count("AAB212")),to_char(substrb(dump(min ("AAB212"),16,0,32),1,120))
,to_char(substrb(dump(max("AAB212"),16,0,32),1,120)),to_char(count("AAB213")),to_char (substrb(dump(
min("AAB213"),16,0,32),1,120)),to_char(substrb(dump(max ("AAB213"),16,0,32),1,120)),to_char(count("AAB214")),to_char(substrb(dump(min ("AAB214"),16,0,32),1,120)),to_char(substrb(dump(max("AAB214"),16,0,
32),1,120)),to_char(count("AAB215")),to_char(substrb(dump(min ("AAB215"),16,0,32),1,120)),to_char(substrb(dump(max("AAB215"),16,0,32),1,120)),to_char (count("AAE011")),to_char(substrb(dump(min("AAE011")
,16,0,32),1,120)),to_char(substrb(dump(max("AAE011"),16,0,32),1,120)),to_char(count ("AAE036")),to_c
har(substrb(dump(min("AAE036"),16,0,32),1,120)),to_char(substrb(dump(max ("AAE036"),16,0,32),1,120)),to_char(count("AAE017")),to_char(substrb(dump(min ("AAE017"),16,0,32),1,120)),to_char(substrb(dump(ma
x("AAE017"),16,0,32),1,120)),to_char(count("SJCQNY")),to_char(substrb(dump(min ("SJCQNY"),16,0,32),1,120)),to_char(substrb(dump(max("SJCQNY"),16,0,32),1,120)) from  "LEMIS_4307"."AB13" t /*
NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV, NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL*/

Global Information
------------------------------
 Status              :  DONE (ALL ROWS)
 Instance ID         :  1
 Session             :  SYS (1837:1553)
 SQL ID              :  5k014mmtyr7qw
 SQL Execution ID    :  16777216
 Execution Started   :  10/17/2016 22:02:26
 First Refresh Time  :  10/17/2016 22:02:32
 Last Refresh Time   :  10/17/2016 22:02:55
 Duration            :  29s
 Module/Action       :  DBMS_SCHEDULER/ORA$AT_OS_OPT_SY_1
 Service             :  SYS$USERS
 Program             :  oracle@sjjh (J001)
 Fetch Calls         :  1

Global Stats
=================================================
| Elapsed |   Cpu   |  Other   | Fetch | Buffer |
| Time(s) | Time(s) | Waits(s) | Calls |  Gets  |
=================================================
|      28 |      28 |     0.09 |     1 |   307K |
=================================================

SQL Plan Monitoring Details (Plan Hash Value=3367417341)
======================================================================================== ===========================================
| Id |          Operation           | Name |  Rows   | Cost  |   Time    | Start  |  Execs |   Rows   | Activity | Activity Detail |
|    |                              |      | (Estim) |       | Active(s) | Active |        | (Actual) |   (%)    |   (# samples)   |
======================================================================================== ===========================================
|  0 | SELECT STATEMENT             |      |         |       |        24 |     +6 |      1 |        1 |          |                 |
|  1 |   SORT AGGREGATE             |      |       1 |       |        28 |     +2 |      1 |        1 |    34.48 | Cpu (10)        |
|  2 |    APPROXIMATE NDV AGGREGATE |      |     29M | 89482 |        29 |     +1 |      1 |      27M |    55.17 | Cpu (16)        |
|  3 |     TABLE ACCESS FULL        | AB13 |     29M | 89482 |        25 |     +5 |      1 |      29M |    10.34 | Cpu (3)         |
======================================================================================== ===========================================

dbms_sqltune.report_sql_monitor过程接受几种输入参数来指定执行，报告的详细级别与报告类型 (‘TEXT’,’HTML’或’XML’)。缺省情况下，如果没有指定参数将会对最后所监控的到SQL生成文本类型 的SQL监控报告。

SQL> desc dbms_sqltune.report_sql_monitor
Parameter           Type     Mode Default?
------------------- -------- ---- --------
(RESULT)            CLOB
SQL_ID              VARCHAR2 IN   Y
SESSION_ID          NUMBER   IN   Y
SESSION_SERIAL      NUMBER   IN   Y
SQL_EXEC_START      DATE     IN   Y
SQL_EXEC_ID         NUMBER   IN   Y
INST_ID             NUMBER   IN   Y
START_TIME_FILTER   DATE     IN   Y
END_TIME_FILTER     DATE     IN   Y
INSTANCE_ID_FILTER  NUMBER   IN   Y
PARALLEL_FILTER     VARCHAR2 IN   Y
PLAN_LINE_FILTER    NUMBER   IN   Y
EVENT_DETAIL        VARCHAR2 IN   Y
BUCKET_MAX_COUNT    NUMBER   IN   Y
BUCKET_INTERVAL     NUMBER   IN   Y
BASE_PATH           VARCHAR2 IN   Y
LAST_REFRESH_TIME   DATE     IN   Y
REPORT_LEVEL        VARCHAR2 IN   Y
TYPE                VARCHAR2 IN   Y
SQL_PLAN_HASH_VALUE NUMBER   IN   Y

也可以使用以下方式来生成SQL监控报告:

SQL> set long 10000000
SQL> set longchunksize 10000000
SQL> set linesize 200
SQL> select dbms_sqltune.report_sql_monitor from dual;

REPORT_SQL_MONITOR
---------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------- ------------------------
SQL Monitoring Report

SQL Text
------------------------------
/* SQL Analyze(1) */ select /*+ full(t) no_parallel(t) no_parallel_index(t) dbms_stats  cursor_sharing_exact use_weak_name_resl dynamic_sampling(0) no_monitoring no_substrb_pad  */to_char(count("MONEY_N
O")),to_char(substrb(dump(min("MONEY_NO"),16,0,32),1,120)),to_char(substrb(dump(max ("MONEY_NO"),16,0,32),1,120)),to_char(count("PAY_INFO_NO")),to_char(substrb(dump(min ("PAY_INFO_NO"),16,0,32),1,120)),
to_char(substrb(dump(max("PAY_INFO_NO"),16,0,32),1,120)),to_char(count ("PAY_MONEY")),to_char(substr
b(dump(min("PAY_MONEY"),16,0,32),1,120)),to_char(substrb(dump(max ("PAY_MONEY"),16,0,32),1,120)),to_char(count("MONEY_TYPE")),to_char(substrb(dump(min ("MONEY_TYPE"),16,0,32),1,120)),to_char(substrb(dum
p(max("MONEY_TYPE"),16,0,32),1,120)),to_char(count("CALC_MAN_SUM")),to_char(substrb (dump(min("CALC_MAN_SUM"),16,0,32),1,120)),to_char(substrb(dump(max ("CALC_MAN_SUM"),16,0,32),1,120)),to_char(count("C
ALC_BASE")),to_char(substrb(dump(min("CALC_BASE"),16,0,32),1,120)),to_char(substrb(dump (max("CALC_B
ASE"),16,0,32),1,120)),to_char(count("MONEY_ID")),to_char(substrb(dump(min ("MONEY_ID"),16,0,32),1,120)),to_char(substrb(dump(max ("MONEY_ID"),16,0,32),1,120)),to_char(count("CORP_ID")),to_char(substrb(
dump(min("CORP_ID"),16,0,32),1,120)),to_char(substrb(dump(max ("CORP_ID"),16,0,32),1,120)),to_char(count("PAYED_MONEY")),to_char(substrb(dump(min ("PAYED_MONEY"),16,0,32),1,120)),to_char(substrb(dump(ma
x("PAYED_MONEY"),16,0,32),1,120)),to_char(count("CALC_PRD")),to_char(substrb(dump(min ("CALC_PRD"),1
6,0,32),1,120)),to_char(substrb(dump(max("CALC_PRD"),16,0,32),1,120)),to_char(count ("SRC_TYPE")),to_char(substrb(dump(min("SRC_TYPE"),16,0,32),1,120)),to_char(substrb (dump(max("SRC_TYPE"),16,0,32),1,1
20)),to_char(count("PAYED_FLAG")),to_char(substrb(dump(min ("PAYED_FLAG"),16,0,32),1,120)),to_char(substrb(dump(max("PAYED_FLAG"),16,0,32),1,120))  from "SJGX_YB"."LV_CROPFUNDPAR" t /*
ACL,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV, NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL,NDV,NIL,NIL*/

Global Information
------------------------------
 Status              :  DONE (ALL ROWS)
 Instance ID         :  1
 Session             :  SYS (146:19)
 SQL ID              :  6sbw88979vmcv
 SQL Execution ID    :  16777216
 Execution Started   :  10/18/2016 22:01:04
 First Refresh Time  :  10/18/2016 22:01:11
 Last Refresh Time   :  10/18/2016 22:01:38
 Duration            :  34s
 Module/Action       :  DBMS_SCHEDULER/ORA$AT_OS_OPT_SY_4
 Service             :  SYS$USERS
 Program             :  oracle@sjjh (J001)
 Fetch Calls         :  1


Global Stats
=================================================
| Elapsed |   Cpu   |  Other   | Fetch | Buffer |
| Time(s) | Time(s) | Waits(s) | Calls |  Gets  |
=================================================
|      34 |      34 |     0.11 |     1 |   294K |
=================================================

SQL Plan Monitoring Details (Plan Hash Value=3534073399)
======================================================================================== =====================================================
| Id |          Operation           |      Name      |  Rows   | Cost  |   Time    |  Start  | Execs |   Rows   | Activity | Activity Detail |
|    |                              |                | (Estim) |       | Active(s) |  Active |       | (Actual) |   (%)    |   (# samples)   |
======================================================================================== =====================================================
|  0 | SELECT STATEMENT             |                |         |       |        28 |      +7 |     1 |        1 |          |                 |
|  1 |   SORT AGGREGATE             |                |       1 |       |        33 |      +2 |     1 |        1 |    40.00 | Cpu (14)        |
|  2 |    APPROXIMATE NDV AGGREGATE |                |     24M | 80111 |        35 |      +0 |     1 |      39M |    54.29 | Cpu (19)        |
|  3 |     MAT_VIEW ACCESS FULL     | LV_CROPFUNDPAR |     24M | 80111 |        28 |      +7 |     1 |      39M |     2.86 | Cpu (1)         |
======================================================================================== =====================================================

在Global Information部分，Status显示为DONE，说明SQL语句已经执行完成了。Time Active(s)列 显示操作已经执行了多长时间。Start Active列，以秒为单位，代表SQL语句执行的开始。在这个报 告中，MAT_VIEW ACCESS FULL是ID 3是第一个被执行的(+7s Start Active)并且执行了28秒。

Start列显示该操作被执行的次数。Rows(Actual)列显示被处理的行数，Rows(Estim)列显示优化器所 评估的行数。Memory与Temp列指示每个操作所消耗的内存与临时空间的大小。

Activity(percent)与Activity Detail(sample #)是通过连接v$sql_plan_monitor与v $active_session_history视图而得到。Activity(percent)显示执行计划中每个操作所占数据库时间 的百分比。Activity Detail(sample#)显示了活动的属性(比如CPU或等待事件)。在这个报告中，ID 2消耗了的数据库时间百分比为54.29%（APPROXIMATE NDV AGGREGATE）。活动由19samples组成。最 后一列,Progress,显示了v$session_longops视图所监控到的操作信息。

启用与禁用SQL监控
SQL监控功能当statistics _level参数被设置为all或typical(缺省值)时缺省是开启的。额外， control_management_pack_access参数必须设置为diagnostic+tuning(缺省值),因为SQL监控是 Oracle数据库优化包的一个功能。SQL监控对于所有运行时间长的查询会自动启动。

有两种语句级别的hint可以用来强制或者阻止SQL语句被监控。为了强制SQL监控，使用monitor hint:

select /*+ MONITOR */ from dual;

这种hint只有当control_management_pack_access参数被设置为diagnostic+tuning时才生效。为了 阻止SQL语句被监控可以使用no_monitor hint。