Page History
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Scan Count A "scan" can represent any of these access methods:• A
- A table scan.
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- Access using a clustered index. Each time the query starts at the root page of the index and follows pointers to the data pages, it is counted as a scan.
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- Access using a non-clustered index. Each time the query starts at the root page of the index and follows pointers to the leaf level of the index (for a covered query) or to the data pages, it is counted.
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- If queries run in parallel, each worker process access to the table is counted as a scan.
More Displays additional information according to the specified operation. For example, in a table scan operation, the scan type (forward/backward), I/O size and buffer replacement strategy will be displayed.
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The table below describes the information displayed for major operation types .
Table 9-9 Major 9 Major operations
Column Description
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Major Operation Type Displays the major types of the operators.• The
- The operators in the Execution Plan tree are separated into the following major types:
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- Table (any Read access to table)
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- Index (any Read access to index)
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- Sort (any sort operation)
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- Join (any join operation)
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- Spooling
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- Other (all other operations)
Estimated Cost Displays the total estimated cost breakdown according to major operation types.
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The table below describes the information displayed for regular operation types.
Table 9-10 Operations10 Operations
Column Description
Click to locate and highlight the operators in the Execution Plan tree that match the selected operation type.
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Major Operation Type Displays the major types of the operators. The operators in the Execution Plan tree are separated into the following major types:• Table
- Table (any access to table)
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- Index (any access to index)
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- Sort (any sort operation)
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- Join (any join operation)
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- Spooling
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- Other (all other operations)
Estimated Cost Total estimated cost breakdown according to operation types.
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Objects Indicates the number of referenced tables/indexes of the specified operation type.
About viewing general properties of a selected statement
The Properties item under the More tab displays general details of the selected statement. The table below describes the properties displayed for a selected statement.
Table 9-11 Selected 11 Selected statement properties
Column Description
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The History view is divided into the following areas:• Main
- Main area
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- Change history area
About the Main area
The Main area (upper area) displays Resource Consumption Over Time vs. Cost and Changes Over Time.
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The Change History area (lower area) displays all the Access Plan changes made over a specified time period.
About viewing Access Plan Changes
The Access Plan Changes view displays a list of all the Access Plans of the statement as detected by the Explain Statement process.
Table 9-12 Access 12 Access Plan Changes table
Column Description
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The table below describes the information displayed in the Statement's View table.
Table 9-13 Statement13 Statement's View table
Column Description
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Table Scans Displays the number of Table Scans performed in the specified statement.
Table 9-13 Statement13 Statement's View table
Column Description
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The Actions tab, on the Precise bar, lets you perform additional actions. You can perform the following actions:• Create
- Create a new statement
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- Open an existing statement
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- Edit an existing statement
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- Re-Explain an existing statement
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- Display the Sybase plan using Sybase SQL Advantage and Interactive SQL
Creating a new statement
You can create a new Statement and save it in the PMDB in a logical cabinet and folder hierarchy. You can also rewrite statements and view their Access Plans.
To create a new statement1. On
- On the Precise bar, click Actions>New.
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- In the New Statement dialog box, choose the relevant properties for the new statement from the drop-down lists and enter a statement name, as follows:
- Instance Indicates the name of the instance that the statement belongs to.
- Cabinet Indicates the name of the cabinet that the statement is saved in (creates a cabinet if it does not already exist).
- Folder Indicates the name of the folder that the statement is saved in (creates a folder if it does not already exist).
- Name Indicates the name of the statement (generated randomly).
- Database Indicates the name of the database where the statement is running.
- User Indicates the statement's parsing user.
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- Enter the SQL text for the statement in the text frame.
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- Click OK.
The new statement is saved in the PMDB in a logical cabinet and folder hierarchy.
Opening an existing statement
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