oracle每一小时创建一个快照，收集了数据库很多信息，内容量十分丰富，我们可以手动创建快照，仍然用到sys.dbms_workload_repository，里面有过程create_snapshot. select * from dba_hist_snapshot; 数据库现在总共创了52个快照。 dba_hist_baseline， dba_hist_undostat
，dba_hist_waitstat ....里面有很多视图值得我们去看看，对于理解awr机制很有用
以select * from dba_hist_waitstat;举例 我们再查数据库等待事件： select * from v$waitstat; 从上面发现snap_id为439里的数据都是从v$waitstat视图里取样的。 下面我们生成一个awr报告：（也可以用em生成报告） SQL> @ /u01/app/oracle/product/11.2.0/dbhome_1/rdbms/admin/awrrpt.sql
Current Instance ~~~~~~~~~~~~~~~~
DB Id DB Name Inst Num Instance ----------- ------------ -------- ------------ 3848072073 ORCL3939 1 orcl3939
Specify the Report Type ~~~~~~~~~~~~~~~~~~~~~~~ Would you like an HTML report, or a plain text report? Enter ‘html‘ for an HTML report, or ‘text‘ for plain text Defaults to ‘html‘ 输入 report_type 的值: ................ ................ Specify the number of days of snapshots to choose from ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Entering the number of days (n) will result in the most recent (n) days of snapshots being listed. Pressing <return> without specifying a number lists all completed snapshots.
输入 num_days 的值: 5
Listing the last 5 days of Completed Snapshots
Snap Instance DB Name Snap Id Snap Started Level ------------ ------------ --------- ------------------ ----- orcl3939 ORCL3939 450 20 4月 2015 00:00 1
Specify the Begin and End Snapshot Ids ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 输入 begin_snap 的值:
.................... ................... 截自部分：
WORKLOAD REPOSITORY report for
DB Name DB Id Instance Inst Num Startup Time Release RAC ------------ ----------- ------------ -------- --------------- ----------- --- ORCL3939 3848072073 orcl3939 1 23-4月 -15 11:03 11.2.0.1.0 NO
Host Name Platform CPUs Cores Sockets Memory(GB) ---------------- -------------------------------- ---- ----- ------- ---------- localhost.locald Linux IA (32-bit) 2 .99
Snap Id Snap Time Sessions Curs/Sess --------- ------------------- -------- --------- Begin Snap: 488 23-4月 -15 22:00:53 42 4.5 End Snap: 489 23-4月 -15 23:00:07 36 4.9 Elapsed: 59.24 (mins) DB Time: 9.48 (mins)
Cache Sizes Begin End ~~~~~~~~~~~ ---------- ---------- Buffer Cache: 72M 72M Std Block Size: 8K Shared Pool Size: 152M 152M Log Buffer: 5,952K
Load Profile Per Second Per Transaction Per Exec Per Call ~~~~~~~~~~~~ --------------- --------------- ---------- ---------- DB Time(s): 0.2 0.6 0.00 0.07 DB CPU(s): 0.1 0.2 0.00 0.02 Redo size: 18,596.5 68,566.9 Logical reads: 354.8 1,308.3 Block changes: 132.5 488.6 Physical reads: 7.9 29.2 Physical writes: 2.8 10.3 User calls: 2.4 9.0 Parses: 9.7 35.7 Hard parses: 0.8 2.9 W/A MB processed: 0.1 0.2 Logons: 0.1 0.3 Executes: 34.6 127.5 Rollbacks: 0.0 0.0 Transactions: 0.3
Instance Efficiency Percentages (Target 100%) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Buffer Nowait %: 100.00 Redo NoWait %: 100.00 Buffer Hit %: 97.77 In-memory Sort %: 100.00 Library Hit %: 94.34 Soft Parse %: 91.99 Execute to Parse %: 72.02 Latch Hit %: 99.99 Parse CPU to Parse Elapsd %: 46.20 % Non-Parse CPU: 91.64
Shared Pool Statistics Begin End ------ ------ Memory Usage %: 77.23 82.51 % SQL with executions>1: 75.48 77.77 % Memory for SQL w/exec>1: 69.86 78.52
Top 5 Timed Foreground Events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Avg wait % DB Event Waits Time(s) (ms) time Wait Class ------------------------------ ------------ ----------- ------ ------ ---------- DB CPU 175 30.7 db file sequential read 9,109 117 13 20.6 User I/O db file scattered read 1,324 29 22 5.0 User I/O virtual circuit wait 272 22 83 4.0 Network log file sync 291 10 34 1.8 Commit Host CPU (CPUs: 2 Cores: Sockets: ) ~~~~~~~~ Load Average Begin End %User %System %WIO %Idle --------- --------- --------- --------- --------- --------- 0.62 0.13 2.6 0.7 3.5 96.3
Instance CPU ~~~~~~~~~~~~ % of total CPU for Instance: 3.1 % of busy CPU for Instance: 84.3 %DB time waiting for CPU - Resource Mgr: 0.0
Memory Statistics ~~~~~~~~~~~~~~~~~ Begin End Host Mem (MB): 1,010.8 1,010.8 SGA use (MB): 264.0 264.0 PGA use (MB): 116.6 79.2 % Host Mem used for SGA+PGA: 37.66 33.95
............. ............. db time:所有活动session的总时间 正常情况下，db time 和cpu time时间大致相等，但是如果是性能问题，往往db time 是 cpu time很多倍。 AWR信息量很大,不但统计了数据库的几乎所有的历史信息而且包括系统信息。
Current Instance
~~~~~~~~~~~~~~~~
DB Id DB Name Inst Num Instance
----------- ------------ -------- ------------
3848072073 ORCL3939 1 orcl3939
Instances in this Workload Repository schema
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DB Id Inst Num DB Name Instance Host
------------ -------- ------------ ------------ ------------
* 3848072073 1 ORCL3939 orcl3939 localhost.lo
caldomain
3848072073 1 ORCL3939 orcl3939 cmwap.cqmc.c
om
Using 3848072073 for database Id
Using 1 for instance number
Specify the number of days of snapshots to choose from
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Entering the number of days (n) will result in the most recent
(n) days of snapshots being listed. Pressing <return> without
specifying a number lists all completed snapshots.
