Monday, July 30, 2012

How to read AWR Report


DB IOPS & Throughput from AWR report




Report Header

This section  provides database name, id, instance if RAC , platform information and snap interval. 

Load Profile



DB time(s):
Its the amount of time oracle has spent performing database user calls. Not it does not include background processes.
DB CPU(s):
Its the amount of CPU time spent on user calls. Same as DB time it does not include background process. The value is in microseconds
Redo size:
average transaction generates  redo data along with redo per second.
Logical reads:
Consistent Gets+ DB blocks Gets = Logical reads
Block Changes:
The number of block modified during the sample interval
Physical reads:
No of block request causing I/O operation
Physical writes:
Number of physical writes performed
User calls:
Number of user queries generated
Parses:
The total of all parses; both hard and soft.
Hard Parses: 
The parses requiring a completely new parse of the SQL statement. These consume both latches and shared pool area.
Soft Parses:
Soft parses are not listed but derived by subtracting the hard parses from parses. A soft parse reuses a previous hard parse; hence it consumes far fewer resources.
Sorts:
No of sorts performed
Logons:
No of logons during the interval
Executes:
No of SQL Executes
Transactions
No of transactions per second

Shared Pool Statistics



BeginEnd
Memory Usage %:73.8675.42
% SQL with executions>1:92.6193.44
% Memory for SQL w/exec>1:50.0055.00

The memory usage statistics of shared pool is shown.

Idealy this should be lesser. If it is very high like beyond 90, this shows the contention
in the shared pool.
 it could mean that your shared pool is tool small and if the percent is in 50 for example then this could mean that you shared pool is too large


Instance Efficiency Percentages (Target 100%)

Instance efficiency should be close to 100 %

Buffer Nowait %:99.99Redo NoWait %:100.00
Buffer Hit %:93.06In-memory Sort %:100.00
Library Hit %:98.67Soft Parse %:98.20
Execute to Parse %:99.99 Latch Hit %:99.98
Parse CPU to Parse Elapsd %:99.99 % Non-Parse CPU:96.21

Top 5 Timed Foreground Events


time is very important component.


RAC Stastics


Time model stastics

SQL Statistics can be checked


SQL ordered by Elapsed Time 
SQL ordered by CPU Time 
SQL ordered by Gets 
SQL ordered by Reads

IO Stats section

The Av Rd(ms) should not cross beyond 10 which is considered to be IO bottleneck

Advisory Statistics can be checked


Buffer Pool Advisory 
PGA Aggr Summary 
PGA Aggr Target Stats 
PGA Aggr Target Histogram 
PGA Memory Advisory 
Shared Pool Advisory 
SGA Target Advisory 
Streams Pool Advisory 
Java Pool Advisory

init.ora Parameters is shown which shows the list of parameters set at instance level



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