| Purpose |
| Best Practices |
| Pro-Active Problem Avoidance and Diagnostic Collection |
| Performance Service Request Diagnostic Collection (SRDC) documents |
| Troubleshooting Steps |
| General Performance |
| AWR Generation |
| AWR Interpretation |
| Buffer Busy Contention |
| Cache Buffers Chains Latch Contention |
| Configuration Parameters |
| Connection Timeouts: Errors ORA-3135/ORA-3136 |
| Deadlocks: Error ORA-00060 |
| Disk I/O |
| Enqueue/Locks |
| High Numbers of Child Cursors/High Cursor Version Counts |
| Hung database |
| Latches |
| Library Cache |
| Log File Sync |
| Mutex Contention |
| Operating System (OS) |
| Paging/Memory |
| Slow Database |
| SQL Issue Diagnosis Using DBMS_SQLDIAG |
| SQL Tuning |
| SYSAUX Tablespace Issues |
| TKProf Runtime Errors |
| Upgrade |
| Virtual Circuit Waits |
| 'WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK!' |
| Community Discussions |
| References |
APPLIES TO:
Oracle Database - Enterprise Edition - Version 10.1.0.2 and laterOracle Database - Standard Edition - Version 10.1.0.2 and later
Oracle Database - Personal Edition - Version 10.1.0.2 and later
Information in this document applies to any platform.
PURPOSE
This article provides a central point for Performance Troubleshooting advice.
You can access categorised Troubleshooting information via the following:
Document 1542678.2 Troubleshooting Assistant: SQL Performance Issues
This articles supersedes :
Best Practices
Pro-Active Problem Avoidance and Diagnostic Collection
Although some problems may be unforeseen, in many cases problems may be avoidable if signs are detected early enough. Additionally, if an issue does occur, it is no use collecting information about that issue after the event. For information on suggested preparations to avoid issues and in case diagnostics are required, see:
Document 1477599.1 Best Practices Around Data Collection For Performance Issues
Performance Service Request Diagnostic Collection (SRDC) documents
Service Request Data Collection (SRDC) documents have been specially designed to provide the reader with the necessary instructions to provide a step by step guide to collecting information for a various common Database Performance Issues.
TROUBLESHOOTING STEPS
General Performance
The following articles can help with the interpretation of diagnostics to troubleshoot various issues:
Document 390374.1 Oracle Performance Diagnostic Guide (OPDG)
AWR Generation
To troubleshoot the failure to collect AWR snapshots or reports, See:
Document 1363422.1 Automatic Workload Repository (AWR) Reports - Start Point
AWR Interpretation
How to troubleshoot performance issues using AWR snapshots or reports, See:
Buffer Busy Contention
To troubleshoot issues where Buffers have become Busy due to concurrent access, see:
Cache Buffers Chains Latch Contention
To troubleshoot issues caused by contention due to multiple sessions waiting to read the same block, see:
Configuration Parameters
Database parameters are designed so that the default is appropriate for the majority of cases. The following article discusses Optimizer Specific Parameters:
Connection Timeouts: Errors ORA-3135/ORA-3136
To troubleshoot issues caused by Connection Timeouts when errors such as ORA-3135 or ORA-3136 are seen, see:
Deadlocks: Error ORA-00060
For issues related to Deadlocks,refer to :
Document 1509919.1 Master Note for Database Error ORA-00060
Disk I/O
For issues related to Disk Input/Ouput (I/O),refer to :
Document 1275596.1 How to Tell if the IO of the Database is Slow
Enqueue/Locks
For locking issues refer to :
Document 15476.1 FAQ about Detecting and Resolving Locking Conflicts
High Numbers of Child Cursors/High Cursor Version Counts
When a SQL statement is executed, Oracle will try to match that statement up with an existing identical statement that has already been executed and attempt to reuse the stored parsed representation of it (which is stored within a cursor structure in the library cache). If the existing information in the cursor for that statement cannot be used, a new version of that statement will be created and used instead. If lots of versions of a particular statement are created, Oracle has to search through the versions to determine which (if any) can be shared. In extreme circumstances, this can cause mutex contention and other issue that degrade the database performance. In order to troubleshoot these issues and determine the cause, see:
Hung database
To troubleshoot cases where the database appears to have hung, refer to :
Document 452358.1 How to Collect Diagnostics for Database Hanging Issues
Latches
To troubleshoot issues where there is contention on 'cache buffers chains' latches see:
Library Cache
For issues related to contention in the Library Cache
Log File Sync
To troubleshoot issues where 'log file sync' is a primary cause of session wait activity, see:
Mutex Contention
For issues related to Mutex contention, refer to :
Document 1349387.1 Troubleshooting 'cursor: pin S wait on X' waits
Document 1357946.1 Troubleshooting 'library cache: mutex X' waits.
Document 1356828.1 FAQ: 'cursor: mutex ..' / 'cursor: pin ..' / 'library cache: mutex ..' Type Wait Events
Operating System (OS)
To troubleshoot Operating System (OS) related issues see:
Document 148176.1 Diagnosing hardware configuration induced performance problems
Paging/Memory
If heavy paging activity is seen and the database appears to be running more slowly than normal, refer to :
Slow Database
To troubleshoot occasions where the database appears to be running more slowly than normal, refer to :
SQL Issue Diagnosis Using DBMS_SQLDIAG
An increasing number of issues can be detected, diagnosed and avoided using the DBMS_SQLDIAG package. For details see:
SQL Tuning
For issues with individual queries, refer to the following troubleshooting documents:
Document 745216.1 * Query Performance Degradation - Upgrade Related - Recommended Actions
Document 179668.1 * TROUBLESHOOTING: Tuning Slow Running Queries
Document 33089.1 * TROUBLESHOOTING: Possible Causes of Poor SQL Performance
Document 372431.1 * TROUBLESHOOTING: Tuning a New Query
Document 122812.1 * TROUBLESHOOTING: Tuning Queries That Cannot be Modified
Document 163563.1 * TROUBLESHOOTING: Advanced Query Tuning
Document 1386036.1 How To Diagnose Issues Where Plans Are Different From Different Clients
SYSAUX Tablespace Issues
TKProf Runtime Errors
Upgrade
To troubleshoot issues encountered after upgrading a database see:
Document 160089.1 TROUBLESHOOTING: Server Upgrade Results in Slow Query Performance
For advice on how to avoid such issues before upgrading, see:
Document 785351.1 Oracle 11gR2 Upgrade Companion
Document 1645862.1 Things to Consider Before Upgrading to 11.2.0.4 to Avoid Poor Performance or Wrong Results
Document 1392633.1 Things to Consider Before Upgrading to 11.2.0.3 to Avoid Poor Performance or Wrong Results
Document 1320966.1 Things to Consider Before Upgrading to 11.2.0.2 to Avoid Poor Performance or Wrong Results
Virtual Circuit Waits
'WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK!'
To troubleshoot issues when the database detects that a waiter has waited for a resource for longer than a particular threshold and he message "WAITED TOO LONG FOR A ROW CACHE ENQUEUE LOCK!" appears in the alert log, See:
Community Discussions
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