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Additional information on In Oracle sub-states is available in the stacked bar graph of the In Oracle view and on the In Oracle tab of the table in the Association area. See “IWait States - I/O wait” on page 38wait.
About In Oracle data for an object
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The Overview, in the Activity tab, displays a table listing the I/O Wait sub-states for this Oracle file. Additional information on In Oracle sub-states is available in the stacked bar graph of the In Oracle view and on the In Oracle tab of the table in the Association area. See “ISee Wait States - I/O wait” on page 38wait.
About the In Oracle view of an Oracle file
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The Dictionary view, in the Activity tab, describes the properties of the Oracle file. The information displayed is equivalent to information that can be found in the DBA_DATA_FILES table.
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You can define an Extended Collection when you need to carry out a more intensive investigation into a particular performance problem. It lets you capture trace-level information from Oracle, allowing you to see Oracle wait event information for sessions and statements. You can, for example, find a unique index contention or ITL contentions.
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- Overview
- In Oracle
- Overall Activity
See “About About the Extended Collection entity” on page 75entity.
About the overview of a session or recent session
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Try to only include the entities that you need and do not run too many extended collections simultaneously. Although the overhead is still much less than for SQL_TRACE, there can be a slight performance penalty in having to write a lot of information to the traces file on the monitored server. |
See “About About the Extended Collection entity.
entity” on page 75. To define extended collections
- Click the Define Extended Collection button to open the Define Extended Collection dialog box.
- In the Instance list, select the appropriate instance name.
- If appropriate, type in the Collection name.
- For Start At date and time, select the following data:
- day (number)
- month (name)
- year (number)
- hour (number)
- minute (number)
- Type the desired maximum number of megabytes for collection information.
- Define the criteria for activities to be gathered in the collection. For each entity listed in the Entity column, define whether to include or exclude the entity to the collection.
- Click OK to accept or Cancel to reject the defined entities.
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- In the Instance list, choose the item you want to analyze.
- In the Time Frame list, choose the period of time you want to analyze.
- On the View controls in the Main area, click Overview. Examine the entire instance and determine which are the dominant resources that are consumed by your system. For our example, we have an Activity tab that shows an instance that is fairly busy. In the Main area, the instance shows that it has spent 1 day out of 7 executing. But it has spent 40% of that time on Other Lock Wait. This is an unproductive wait.
Launch to the Statistics tab to find out more about the underlying Oracle wait events comprising the Other Lock Wait. It is most likely to be an enqueue. In fact, the instance has spent over 50% of its time in unproductive waits (not using CPU or I/O).
Info As a rule of thumb, a healthy system should have a high Using CPU value; a 10-15% I/O Wait, and the remaining non-productive wait states should show values that are as low as possible. For databases that process large data volumes, such as a data warehouse, the I/O Wait percentage may be higher. It is true, however, that applications/statements that experience high Using CPU or I/O Wait times may be performing excessive logical I/Os and should be investigated. To determine this, it is important to look at the actual time spent waiting (in hh:mm:ss) as well as just the percentage.
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