达梦数据库中也提供了类似Oracle AWR的快照功能，通过快照采集不同时间点数据库的性能数据，借此相关数据，我们可以用来分析达梦数据库的性能情况，在进行调优时是十分有帮助的。
首先如何创建AWR快照呢？
--创建包
SQL> SP_INIT_AWR_SYS(1);
DMSQL executed successfully
used time: 529.779(ms). Execute id is 507.
--检查包状态
SQL> SELECT SF_CHECK_AWR_SYS;
SF_CHECK_AWR_SYS
----------------
1
used time: 2.323(ms). Execute id is 508.
说明： 1表示启用，0 表示未启用
--设置快照采集时间
SQL> CALL DBMS_WORKLOAD_REPOSITORY.AWR_SET_INTERVAL(10);
DMSQL executed successfully
used time: 8.054(ms). Execute id is 509.
CALL DBMS_WORKLOAD_REPOSITORY.MODIFY_SNAPSHOT_SETTINGS(1440,30); --设置快照保留时间为1天，采集时间为30分钟。
--手工采集快照
SQL> DBMS_WORKLOAD_REPOSITORY.CREATE_SNAPSHOT();
DMSQL executed successfully
--清理历史快照
CALL DBMS_WORKLOAD_REPOSITORY.AWR_CLEAR_HISTORY();
used time: 55.674(ms). Execute id is 510.
SQL>
--获取快照信息
SELECT * FROM SYS.WRM$_SNAPSHOT;
--产生awr报告
SYS.AWR_REPORT_HTML(1,2,'/tmp','dm_test_0903.HTML');
大家不难看出，针对awr快照的相关操作命令，跟Oracle几乎一致。Oracle DBA真是可以无缝切换了。 下面我们继续来看看达梦数据库的awr报告长什么样子。
第一部分: awr文件表头信息
DB Name DB Id Instance Inst num Startup Time Release DSC
enmotech 697804028 DMDB 1 2021-09-03 13:54:36 DM Database Server x64 V8 NO
Host Name Platform Cpus Cores Sockets Memory (GB)
ecs-1461 Linux 8 1 1 30.63
Snap Id Snap Time Sessions Stmts/Session
Begin Snap: 4 2021-09-03 14:13:11 1 1.0
End Snap: 6 2021-09-03 14:29:37 2 1.0
Elapsed: 16.43(mins)
DB Time: 564.57(mins)
这部分内容主要是针对数据库实例和硬件环境的一些基本信息。
第二部分：报告汇总信息
Report Summary
Memory Pool
Begin End
Memory Pool Size(MB): 3859.35 3863.79
Memory Used(MB): 711.30 782.29
Bytes Allocated From OS(MB): 0 0
Memory used bytes from os(MB): 239.07 243.39
Memory Usage %: 18.43 20.25
% SQL with executions>1: 0 0
% plan with executions>1: 0 0.01
% rowset cache hit count: 0 0
Buffer Pool
Begin/End Name Page Size(Bytes) Total Pages Free Logic Reads Discards Rat Hit %
B FAST 8192 3000 0 281444911939585 281444911939585 100.00
E FAST 8192 3000 0 281444911939585 281444911939585 100.00
B KEEP 8192 1024 1024 281446479159528 281446479159528 100.00
E KEEP 8192 1024 1024 281446628648216 281446628648216 100.00
B NORMAL 8192 49878 31197 281444911939585 281444911939585 99.68
E NORMAL 8192 49878 30974 281444911939585 281444911939585 99.56
B NORMAL 8192 49878 31141 281444911939585 281444911939585 99.65
E NORMAL 8192 49878 31177 281444911939585 281444911939585 99.70
B NORMAL 8192 49878 31128 281444911939585 281444911939585 99.72
E NORMAL 8192 49878 31205 281444911939585 281444911939585 99.59
B NORMAL 8192 49878 31027 281444911939585 281444911939585 99.68
E NORMAL 8192 49878 31171 281444911939585 281444911939585 99.75
B NORMAL 8192 49878 31002 281444911939585 281444911939585 99.74
E NORMAL 8192 49878 31154 281444911939585 281444911939585 99.71
B NORMAL 8192 49878 31098 281444911939585 281444911939585 99.67
E NORMAL 8192 49878 31210 281444911939585 281444911939585 99.66
B NORMAL 8192 49878 31184 281444911939585 281444911939585 99.69
E NORMAL 8192 49878 31164 281444911939585 281444911939585 99.63
B NORMAL 8192 49878 31211 281444911939585 281444911939585 99.78
E NORMAL 8192 49878 31153 281444911939585 281444911939585 99.61
B NORMAL 8192 49878 31169 281444911939585 281444911939585 99.73
E NORMAL 8192 49878 31188 281444911939585 281444911939585 99.61
B NORMAL 8192 49878 31127 281444911939585 281444911939585 99.79
E NORMAL 8192 49878 31124 281444911939585 281444911939585 99.74
B NORMAL 8192 49878 31092 281444911939585 281444911939585 99.59
E NORMAL 8192 49878 31157 281444911939585 281444911939585 99.75
B NORMAL 8192 49878 31240 281444911939585 281444911939585 99.77
E NORMAL 8192 49878 31108 281444911939585 281444911939585 99.62
B NORMAL 8192 49878 31202 281444911939585 281444911939585 99.87
E NORMAL 8192 49878 31127 281444911939585 281444911939585 99.61
B NORMAL 8192 49878 31114 281444911939585 281444911939585 99.63
E NORMAL 8192 49878 31151 281444911939585 281444911939585 99.62
B NORMAL 8192 49878 31144 281444911939585 281444911939585 99.75
E NORMAL 8192 49878 31090 281444911939585 281444911939585 99.88
B NORMAL 8192 49878 31036 281444911939585 281444911939585 99.52
E NORMAL 8192 49878 31127 281444911939585 281444911939585 99.58
B NORMAL 8192 49878 31092 281444911939585 281444911939585 99.68
E NORMAL 8192 49878 31120 281444911939585 281444911939585 99.66
B NORMAL 8192 49878 31146 281444911939585 281444911939585 99.69
E NORMAL 8192 49878 31093 281444911939585 281444911939585 99.82
B NORMAL 8192 49878 31041 281444911939585 281444911939585 99.66
E NORMAL 8192 49878 31240 281444911939585 281444911939585 99.80
B NORMAL 8192 49878 31259 281444911939585 281444911939585 99.73
E NORMAL 8192 49878 31220 281444911939585 281444911939585 99.69
B NORMAL 8192 49878 31126 281444911939585 281444911939585 99.57
E NORMAL 8192 49878 21244 281444911939585 281444911939585 99.65
B NORMAL 8192 49878 21289 281444911939585 281444911939585 99.70
E NORMAL 8192 49878 21336 281444911939585 281444911939585 99.68
B NORMAL 8192 49878 21300 281444911939585 281444911939585 99.71
E NORMAL 8192 49878 21330 281444911939585 281444911939585 99.73
B NORMAL 8192 49878 21374 281444911939585 281444911939585 99.75
E NORMAL 8192 49878 21204 281444911939585 281444911939585 99.80
B NORMAL 8192 49878 21257 281444911939585 281444911939585 99.75
E NORMAL 8192 49878 21218 281444911939585 281444911939585 99.72
B NORMAL 8192 49878 21249 281444911939585 281444911939585 99.84
E NORMAL 8192 49878 21276 281444911939585 281444911939585 99.88
B NORMAL 8192 49878 21388 281444911939585 281444911939585 99.73
E NORMAL 8192 49878 21275 281444911939585 281444911939585 99.70
B NORMAL 8192 49878 21371 281444911939585 281444911939585 99.81
E NORMAL 8192 49878 21296 281444911939585 281444911939585 99.64
B NORMAL 8192 49878 21224 281444911939585 281444911939585 99.71
E NORMAL 8192 49878 21199 281444911939585 281444911939585 99.69
B NORMAL 8192 49878 21091 281444911939585 281444911939585 99.76
E NORMAL 8192 49878 21358 281444911939585 281444911939585 99.74
B NORMAL 8192 49878 21175 281444911939585 281444911939585 99.76
E NORMAL 8192 49878 21217 281444911939585 281444911939585 99.66
B NORMAL 8192 49878 21240 281444911939585 281444911939585 99.87
E NORMAL 8192 49878 21330 281444911939585 281444911939585 99.68
B NORMAL 8192 49878 21222 281444911939585 281444911939585 99.66
E NORMAL 8192 49878 21177 281444911939585 281444911939585 99.67
B NORMAL 8192 49878 21231 281444911939585 281444911939585 99.66
E NORMAL 8192 49878 21214 281444911939585 281444911939585 99.58
B NORMAL 8192 49878 21314 281444911939585 281444911939585 99.71
E NORMAL 8192 49878 21258 281444911939585 281444911939585 99.63
B NORMAL 8192 49878 21294 281444911939585 281444911939585 99.62
E NORMAL 8192 49878 21127 281444911939585 281444911939585 99.73
B NORMAL 8192 49878 21205 281444911939585 281444911939585 99.64
E NORMAL 8192 49878 21155 281444911939585 281444911939585 99.64
B NORMAL 8192 49878 21185 281444911939585 281444911939585 99.68
E NORMAL 8192 49878 21191 281444911939585 281444911939585 99.67
B NORMAL 8192 49878 21248 281444911939585 281444911939585 99.66
E NORMAL 8192 49878 21155 281444911939585 281444911939585 99.69
B NORMAL 8192 49878 21390 281444911939585 281444911939585 99.68
E NORMAL 8192 49878 21291 281444911939585 281444911939585 99.75
B NORMAL 8192 49878 21367 281444911939585 281444911939585 99.68
E NORMAL 8192 49878 21251 281444911939585 281444911939585 99.73
B RECYCLE 8192 39384 39328 281444911939585 281444911939585 69.00
E RECYCLE 8192 39384 39327 281444911939585 281444911939585 69.24
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 68.89
E RECYCLE 8192 39384 39328 281444911939585 281444911939585 69.10
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 88.57
E RECYCLE 8192 39384 39327 281444911939585 281444911939585 69.12
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 69.22
E RECYCLE 8192 39384 39327 281444911939585 281444911939585 96.15
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 68.77
E RECYCLE 8192 39384 39328 281444911939585 281444911939585 68.74
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 68.60
E RECYCLE 8192 39384 39326 281444911939585 281444911939585 78.54
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 68.69
E RECYCLE 8192 39384 39327 281444911939585 281444911939585 68.61
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 68.79
E RECYCLE 8192 39384 39327 281444911939585 281444911939585 69.10
B RECYCLE 8192 39384 39328 281444911939585 281444911939585 69.14
E RECYCLE 8192 39384 39328 281444911939585 281444911939585 68.62
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 69.11
E RECYCLE 8192 39384 39327 281444911939585 281444911939585 88.56
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 68.72
E RECYCLE 8192 39384 39326 281444911939585 281444911939585 78.64
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 69.06
E RECYCLE 8192 39384 39328 281444911939585 281444911939585 68.89
B RECYCLE 8192 39384 39327 281444911939585 281444911939585 68.61
E RECYCLE 8192 39384 39327 281444911939585 281444911939585 96.14
B ROLL 8192 128 128 281444911939585 281444911939585 100.00
E ROLL 8192 128 128 281444911939585 281444911939585 100.00
这部分内容主要是内存组件方面的使用情况，包括开始，结束的大小，命中率等等；通过这部分内容，我们可以判断数据库内存的设置是否合理（当然不能仅仅只看这部分内容）。
第三部分：load profile
Load Profile
Per Second Per Transaction
DB Time(s): 0 0
DB CPU(s): 0 0
Redo size: 4.9 0.2
Logical reads: 27072.1 936.7
Block changes: 1855.0 64.2
Physical reads: 8.4 0.3
Physical writes: 75.0 2.6
User calls: 562.6 19.5
Parses: 0.1 0
Hard parses: 0 0
Logons: 0 0
Logoff: 0 0
Executes: 533.7 18.5
Rollbacks: 2.4 0.1
Commit: 26.5 0.9
Deadlock: 0 0
Transactions: 28.9 0
% Changes changed per read 0 0
Rows per transaction: 0 0
Rows per Sort: 0
这部分内容类似Oracle awr的load profile。不过相关的指标有所区别。从相关指标来看，表达的含义应该是一致的，比如每秒redo日志产生大小，物理读，逻辑读，包括sql每秒的解析情况，以及tps等等。
第4部分内容： 命中率和等待事件top
Instance Efficiency Percentages (Target 100%)
Buffer Nowait %: 100.00 Redo NoWait %: 100.00
Buffer Hit %: 50.00 In-memory Sort %: 100.00
Library Hit %: 100.00 Soft Parse %: 96.31
Execute to Parse %: 99.99 % Non-Parse CPU: 100.00
Top 5 Timed Foreground Events
Event Waits Time(s) Avg wait (ms) % DB time Wait Class
trxid lock wait 59820 1573.912755 11.464 4.65 Transaction
dbfile extend 44 0.181324 0.006 0 System I/O
table lock wait 2 0.000001 0 0 Transaction
这里不多多少，经常看到Oracle awr报告的同学应该很清楚。不过我认为这里命中率也仅仅是供参考了，实际上Oracle 现在我们也几乎不看这个指标了，意义不是太大。其中等待事件这里不多说。达梦数据库的等待事件相对较少，比Oracle 简单太多了。
第5部分内容：报告主体
Main Report
Report Summary
Wait Events Statistics
SQL Statistics
Instance Activity Statistics
IO Stats
Buffer Pool Statistics
Advisory Statistics
Wait Statistics
Undo Statistics
Lock Statistics
Dead Lock Statistics
Seg Statistics
Dictionary Cache Statistics
Library Cache Statistics
Memory Statistics
Sort Statistics
Resource Limit Statistics
Mail Statistics
dm.ini Parameters
Back To Top
Wait Events Statistics
Time Model Statistics
Operating System Statistics
Foreground Wait Class
Foreground Wait Events
Wait Event Histogram
这部分内容主要是一些更为详细的细化信息了，比如等待事件，IO信息，锁信息，undo相关信息，以及字典cache相关信息。同时我们也可以看到，达梦这里也借鉴了类似Oracle一样 的基于时间的统计模型，也有DBtime概念。不过内容相对简单的多，来看看。
Statistic Name Time (s) % of DB Time
CPU time(ms) 32088.82 94.73
parse time(ms) 0.02 0
hard parse time(ms) 0.02 0
DB time(ms) 33873.93
可以看到内容还是非常简单，基础。几乎只有一些最为常见的内容。
另外就是分析达梦awr报告可以看到，后面的IO statistics方面信息也非常简单，如下：
Tablespace IO Stats
ordered by IOs (Reads + Writes) desc
Tablespace Reads Av Reads/s Writes Av Writes/s
TEST 285967 8.44 1702239 50.25
ROLL 0 0 837390 24.72
SYSAUX 0 0 2501 0.07
SYSTEM 0 0 11 0
TEMP 0 0 0 0
MAIN 0 0 0 0
Back to IO Stats
Back To Top
File IO Stats
ordered by Tablespace, File
Tablespace Path Reads Av Reads/s Writes Av Writes/s
MAIN /opt/dm/dmdbms/data/enmotech/MAIN.DBF 0 0 0 0
ROLL /opt/dm/dmdbms/data/enmotech/ROLL.DBF 0 0 837390 24.72
SYSAUX /opt/dm/dmdbms/data/enmotech/SYSAWR.DBF 0 0 2501 0.07
SYSTEM /opt/dm/dmdbms/data/enmotech/SYSTEM.DBF 0 0 11 0
TEMP /opt/dm/dmdbms/data/enmotech/TEMP.DBF 0 0 0 0
TEST /data/dmdata/test01.dbf 47637 1.41 285270 8.42
TEST /data/dmdata/test02.dbf 47751 1.41 283689 8.37
TEST /data/dmdata/test03.dbf 47380 1.40 282626 8.34
TEST /data/dmdata/test04.dbf 47793 1.41 283145 8.36
TEST /data/dmdata/test05.dbf 47422 1.40 281646 8.31
TEST /data/dmdata/test06.dbf 47984 1.42 285863 8.44
可以看到，只有一些常规信息，比如文件每秒的读写次数，最为重要的平均等待读写等指标缺没有。从这里可以看出，目前达梦数据库的性能数据采集方面，做的还不够，期待后面更加完善。。
最后简单总结一下：
达梦数据库的awr报告跟Oracle 类似，包括创建语法，以及相关报告的主体内容；但是很多指标还是太粗；由此可见达梦数据库在性能观测和调优方面可能还需要加强。期待国产数据库功能越来越强，越来越完善！
