oracle performance diagnostic analysis of an important indicator content

  For database environment problems arise in the use of the database, it may be caused by any of the components of which a table space, file system, data files, processes, etc.,

There may even be due to a particular SQL performance statements cause poor system performance issues. Therefore, when the root causes of database problems, a thorough investigation of the problem to be repeated, complicated labor,

But before troubleshooting, performance testing as a technician should first understand what tools, which monitor database performance indicators clear, targeted, no gain, as oracle monitor performance indicators and the use of monitoring and analysis methods:

Index Name	Problem Description and Diagnostic Analysis
Oracle Data Access Data way
Full table scan / sec (Full Scans/sec)	Indicators Description	It refers to the number of full table scans per second. Full table scan can be substantially full table scan or index scan. Because full table scan takes a lot of time, so a full table scan frequency too high CPU utilization is too high, it will affect performance.
	Diagnosing	1,   obtained by using Spotlight conduct SQL problem. 2,   analysis get the object in question through SQL database logs
	indicator anaysis	1 , by using Spotlight or Profiler analyzes to see whether you need a full table scan by the way, to optimize the SQL query performance. 2 , there are a large number of cases for process historical data look-up table data, you can improve query performance by analyzing whether the partition table.
other	Indicators Description	SQL syntax wording problems, leading to excessive consumption of resources CPU / memory
	Diagnosing	1,   obtained by using Spotlight conduct SQL problem. 2,   analysis get the object in question through SQL database logs
	indicator anaysis	Too many nested sub-query or sort grammar and so on, by modifying the SQL implementation
ORACLE database instance parameters Analysis
Buffer Waits Buffer   wait	Indicators Description	It refers to the probability of obtaining waiting in the buffer Buffer
	Diagnosing	Get metrics corresponding values ​​or by using a snapshot Spotlight
	indicator anaysis	Spotlight by using the performance index to be close to 100%;
Buffer hit ratio Buffer   Hit %	Indicators Description	It refers to the data block in the data buffer hit ratio of
	Diagnosing	Get metrics corresponding values ​​or by using a snapshot Spotlight
	indicator anaysis	This value should generally be 90% or more;
Shared area hit rate SharedPool   %	Indicators Description	Shared use of pool
	Diagnosing	Get metrics corresponding values ​​or by using a snapshot Spotlight
	indicator anaysis	By using Spotlight analysis, this value should be generally 90% or more;
Sort of memory usage	Indicators Description	It refers to the ratio of the sort operation in memory. When a query requires a sort, and now sort of memory, lack of memory will use the temporary table space disk sorting, causing IO problem, affecting efficiency.
	Diagnosing	Get metrics corresponding values ​​or by using a snapshot Spotlight
	indicator anaysis	This value is typically close to 100% better performance;
Log File Synchronization Log   file sync	Indicators Description	This wait event means that when a session is complete a thing, LGWR process must wait until the session's redo information is written to the log file from the log buffer to continue execution.
	Diagnosing	Get metrics corresponding values ​​or by using a snapshot Spotlight
	indicator anaysis	This time the event is too long to wait, probably due to submit or update data once too often or too long write time logs;
Redo   Buffer Waits rate Redo   wait	Indicators Description	Waiting for the chance to acquire an in Redo buffer Buffer
	Diagnosing	Get metrics corresponding values ​​or by using a snapshot Spotlight
	indicator anaysis	The performance indicators should be close to 100%;
oracle locks (Locks) performance counter
Queue waiting (enqueue(cs))	Indicators Description	The locking mechanisms to protect shared resources, such as data records in order to avoid two personal update the same data at the same time. enqueue comprising a queuing mechanism, i.e., FIFO ( first in first out ) queuing.
	Diagnosing	By using Spotlight, snapshots, LR monitor to obtain the corresponding index value
	indicator anaysis	如果enqueue等待事件比较显著，则需要根据enqueue等待类型，采取相应的优化方法。 防止多个事务并发使用资源，尽可能少使用锁来提高性能开销。