Analyze Tool
Use the Analyze tool to view and collect statistics, validate structure and list chained rows for database structures such as tables, clusters and indexes.
Ways to open the Analyze Tool
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From DB Navigator |
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From the Explain Plan Tool |
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Collect Statistics
Select the collection method.
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Collection Method |
Description |
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Compute Statistics |
The entire object is scanned to gather data. The larger the object, the longer it takes to complete the analysis. Select this option only if the object is small. |
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Estimate Statistics |
Sample by rows or percentage of the object. The accuracy of the statistics depends on the representatives of the sampling. This option suits large objects. |
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Delete Statistics |
Delete the statistics gathered for the object. |
Validate Structure
Use to verify the integrity of the selected object.
Select Cascade to additionally verify dependent objects. For example, if you validate the structure of a cluster and select Cascade, SQL Navigator checks all tables and indexes in the cluster.
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Note: Oracle returns an error message if it encounters corruption in the structure of an object. To fix errors: Drop and recreate the object from the commands on the Object Menu. |
List Chained Rows
Use to identify migrated or chained rows in a table or cluster. Having a high percentage of chained rows can impair application performance. UPDATE statements that cause migration and chaining perform poorly. Queries that select migrated or chained rows must perform more I/O than those that do not. For these reasons, it is important to detect and correct them. See Oracle documentation on the possible ways of fixing chained-rows problems.
- The default name for the table that will contain the chained rows information is CHAINED_ROWS. This is defined at View | Preferences | General | Default Tables.
- Click Create Chained Rows Table to create the table. Watch for verification in the Output Window.
- Click List Chained Rows to collect the information. Watch for verification in the Output Window.
- To view the information select the CHAINED_ROWS table in DB Navigator and click Object Menu | Quick Browse.