Page History
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From the Association area, you can also drill down to another entity by clicking a table row. A drilldown drill-down affects the whole tab: When you drill down to another entity, the Tab heading reflects the new selection, the Main area displays information on the newly selected entity, and the Association area shows data on its associated entities.
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In the Association area, click the row of the database you want to view detailed information for. The Tab heading indicates the newly selected entity; the Main area displays an overview of the database you want to investigate, and the Association area shows general details on the tables that are associated with the database you selected. See For more information about Precise for Sybase tabs, see About Precise for Sybase tabs on page 15.
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The headings in the Replication Agent Configuration Parameters main area are described below.
Table 7- 1 Replication Agent Configuration Parameters headers
| Column | Description |
|---|---|
| Parameter Name | Displays the parameter name. |
| Default Value | Displays the default value for each parameter. |
| Configuration Value | Displays the configuration value for each parameter. |
| Run Value | Displays the run value for each parameter. |
About the Database entity in the Association area
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- Overview
- Column Statistics
About getting an overview of the selected column
Displays general details on the selected column such as type, length, and default value.
About viewing column statistics
This view shows column-level statistics including:
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The following information is displayed:
- Statistics
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- Updated. The date and time that the last modification of the statistics occurred. This can be due to create index, update statistics, or by writing the statistics with optdiag.
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- Steps. The number of steps generated for the column.
- Range Cell
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- Density. A measure of the density of values in the column, after values in frequency count cells has been eliminated. Basically, this is the density of all values that are not highly duplicated. This value is used to estimate the cost of an equality search arguments when the value falls into a range cell.
- Total
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- Density. A measure of the duplicate values in all rows of the column, no matter what cell type they fall into. This value is used to estimate the number of rows that will be returned for a join on this column. It is also used as the selectivity value when the value of an equality search argument is not known at run time.
- Range
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- Selectivity. Prints the default value of .33, unless the value has been updated using the optdiag input mode. This is the value used for range queries if the open ended range search argument (<, <=, >, >=) is not known at optimize time.
- In Between
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- Selectivity. Prints the default value of .25, unless the value has been updated using the optdiag input mode. This is the value used for range queries if the closed range search argument (between, col >= X and col <= Y) is not known at optimize time.
Distribution
Shows the column histogram as the distribution of values within the column.
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For example, a weight of 0.050000 means that the value(s) in the cell occupy 5% of the rows in the column. The weight is very useful to determine when a value or values is becoming highly duplicated-if the weights are fairly uniform, the data is well distributed.
Column entity Association area
You can view general details on the entities that are associated with the selected Column entity in the Association area. It is possible to associate to the Column entity from the Table, Index, and View entities.
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The Views Contain Same Column entity displays views that have the same column as the column displayed in the Main area. The information displayed is the same as displayed in the View entity and can only be associated to from the Column entity.
About getting an overview of the View entity and Views Contain Same Column entity
The Overview displays general details on the View entity such as creation date, number of columns, and the view text.
View entity and Views Contain Same Column entity Association area
You can display general details on the entities that can be associated with the selected View entity in the Association area. It is possible to associate to the View entity from the Database, Table, Column and Index entities.
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The User entity displays general details of the selected user, such as, Roles and Group Name.
User entity Association area
You can view general details on the entities that can be associated to the selected User entity in the Association area. It is possible to associate to the User entity from the Database entity.
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The Database Device entity displays general details, I/O Activity and storage information on the selected device. The following views are available:
- Overview
- Statistics
About getting an overview of the database device entity
The Overview displays the following information:Properties Displays
- Properties. Displays general details on the device, such as full filename (including path), size, I/O Wait, and I/O Activity during the selected time frame.
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- Semaphores. Displays the number of times that a request for a device semaphore was NOT granted immediately (the semaphore was busy) and the task had to wait for the semaphore to be released. This data is meaningful for SMP applications only. When Adaptive Server needs to perform a disk I/O, it gives the task the semaphore for that device, to acquire a block I/O structure. On SMP systems, multiple engines can try to post I/Os to the same device simultaneously. This creates contention for that semaphore, especially if there are hot devices or if the data is not well distributed across devices. A large percentage of I/O requests that waited can indicate a semaphore contention issue. One solution might be to redistribute the data on the physical devices.
- Pages
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- requested. Displays the I/O Activity (pages read and written) during the selected time frame for the selected device, as collected by the Collect Statistics process.
- Space
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- Allocation. Displays free space and used space (in MB) during the selected time frame for the selected device, as collected by the Collect Space Utilization process.
About viewing I/O statistics on a database device
Displays I/O statistics on the device during the selected time frame. The following information is displayed:Semaphores Displays
- Semaphores. Displays the number of times that a request for a device semaphore was NOT granted immediately (the semaphore was busy) and the task had to wait for the semaphore to be released. This data is meaningful for SMP applications only. When Adaptive Server needs to perform a disk I/O, it gives the task the semaphore for that device, to acquire a block I/O structure. On SMP systems, multiple engines can try to post I/Os to the same device simultaneously. This creates contention for that semaphore, especially if there are hot devices or if the data is not well distributed across devices. A large percentage of I/O requests that waited can indicate a semaphore contention issue. One solution might be to redistribute the data on the physical devices.
- Pages
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- requested. Displays the I/O Activity (pages read and written) during the selected time frame for the selected device, as collected by the Collect Statistics process.
Database Device entity Association area
You can view general details on the entities associated to the Database Device entity in the Association area. It is possible to associate to the Database Device entity from the following entities: Instance, Database, Segment, Table, and Index.
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The Segment entity displays general details and space utilization during the selected time frame, for the selected Database Segment.
About getting an overview of segment details
The Overview displays general Segment details, such as number of device extents the Segment occupies and information regarding the segment's space utilization during the selected time frame. The following information is displayed:
- Space
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- Allocation. Displays the amount of free space and used space of the selected segment during the selected time frame, based on the data collected by the Collect Space Utilization process.
Segment entity Association area
You can view general details on the entities that are associated to the selected Segment in the Association area. It is possible to associate to the Segment from the following entities: Database, Table, Index, and Database Device.
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The Data Cache entity displays general information about the selected Data Cache. The following views are available:
- Overview
- Data cache pools
About getting an overview of data cache pools
The Overview displays general Data Cache details, such as size, replacement policy and pool configuration.
About viewing data cache pools
Data Cache Pools can be configured in each cache to enable Sybase to perform large I/Os. The Data Cache Pools view displays information regarding the pools configuration of the selected Data Cache.
The following information is available:
- I/O
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- Size. Shows the size of the buffers in the pool. Specifies the amount of bytes that can be read at once. The default size of the pool is the size of the server's logical page.
- Config
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- Size. The amount of memory space configured for the pool.
- Run
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- Size. The amount of memory space currently assigned for the pool. The value may differ from the config size of the pool because one cannot explicitly configure its size. The value may differ for other pools if you have tried to move space between them, and some of the space could not be freed.
- Wash
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- Size. Size of the Wash area. A portion of each pool is configured as the wash area. After dirty pages (pages that have been changed in cache) pass the wash marker and enter the wash area, Adaptive Server starts an asynchronous I/O on the page. When the write completes, the page is marked clean and remains available in the cache. The space in the wash area must be large enough so that the I/O on the buffer can complete before the page needs to be replaced. For more information, see
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- and Administration.
- APF (%)
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- . Displays the percentage of the pool that can hold unused buffers brought in by asynchronous prefetch.
Data Cache entity Association area
You can view general details on the selected Data Cache entity in the Association area. It is possible to associate to the Data Cache entity from the Instance, Database, Table and Index.
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- Overview
- Performance
- SQL text
About getting an overview of a statement
The Overview displays the following information:
- Statement
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- ID. Displays the statement ID.
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- Database. Displays the database name.
- Parsing
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- User. Displays the parsing user name.
- Most Recent
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- Plan. Displays the date of the most recent plan.
- Last Show
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- Plan. Displays the date of the last shown plan.
- Access
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- Plan. Displays a list of all Access operators in the statement’s explain results.
About viewing the performance of a selected statement
The Performance view displays the following information:
- In Sybase
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- graph
- Buffer Wait
- Network I/O Wait
- Log Full Wait
- Log Wait
- Internal Wait
- Remote Wait
- Lock Wait
- I/O Wait
- Using CPU
- Statement Executions
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- graph. Number of executions overtime.
About viewing the SQL text of a specific statement
The SQL Text view displays the SQL text of the statement.
Statement entity Association area
You can view general details on the statement associated with the selected Table, or Index entity in the Association area. It is possible to associate from the statement to the Table or Index accessed by this statement. There are Table, Index, and Object lists which can be associated to a statement.
The table below describes the information displayed in the Performance tab.
Table 7- 2 Performance tabColumn Description
| Column | Description |
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| Launch icon to SQL |
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| tab | Launches into SQL tab. |
| Statement |
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| ID | Displays the statement ID. |
| In |
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| Sybase | Displays the sum of each In Sybase parameter in the time period from the statistics table - bar with separated values or sum of all In Sybase values. |
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| Text | Displays the statement's text. |
The table below describes the information displayed in the Plan tab.
Table 7- 3 Plan tab
| Column |
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| Description |
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| Launch icon to SQL |
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| tab | Launches into SQL tab. |
| Statement |
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| ID | Displays the statement ID. |
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| Database | Displays the database name. |
| Parsing |
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| User | Displays the parsing user name. |
| Most Recent |
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| Plan | Displays the date of the most recent plan. |
| Last Show |
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| Plan | Displays the date of the last shown plan. |
| Total Estimate |
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| Cost | Displays a graph/number. |
| Table |
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| Scan | Displays Yes or No. |
| Clustered Index |
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| Scan | Displays Yes or No. |
| Clustered Index |
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| Seek | Displays Yes or No. |
| Index |
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| Scan | Displays Yes or No. |
| Index |
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| Seek | Displays Yes or No. |
| Table |
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| Lookup | Displays Yes or No. |
| Sort |
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| Displays Yes or No. |
| Merge |
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| Join | Displays Yes or No. |
| Join |
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| Displays Yes or No. |
| Nested Loop |
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| Join | Displays Yes or No. |
| Parallel |
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| Access | Displays Yes or No. |
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- Overview
- Performance
- SQL text
About getting an overview of batch details
The Overview displays general batch details such as most recent plan and last show plan, as follows:
- Batch
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- ID. Displays the batch ID.
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- Database. Displays the database name.
- Parsing
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- User. Displays the parsing user name.
- Most Recent
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- Plan. Displays the date of the most recent plan.
- Last Show
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- Plan. Displays the date of the last shown plan.
- Access
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- Plan. Displays a list of all Access operators in the batch’s explain results.
About viewing the performance of a batch
The Performance view displays resource consumption and number of statement executions for a batch, as follows:
- In Sybase
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- graph
- Buffer Wait
- Network I/O Wait
- Log Full Wait
- Log Wait
- Internal Wait
- Remote Wait
- Lock Wait
- I/O Wait
- Using CPU
- Statement Executions
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- graph. Number of executions overtime.
About viewing the SQL text of a batch
The SQL text view displays the SQL Text of the batch.
Batch entity Association area
You can view general details on the batch associated with the selected Table, or Index entity in the Association area. It is possible to associate from the batch to the Table or Index entity accessed by this batch. There are Table, Index, and Object lists that can be associated to a batch.
The table below describes the information displayed in the Performance tab.
Table 7- 4 Batch entity Performance tab
| Column |
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| Description |
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| Launch icon to SQL |
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| tab | Launches into SQL tab. |
| Batch |
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| ID | Displays the batch ID. |
| In |
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| Sybase | Displays the sum of each In Sybase parameter in the time period from the statistics table - bar with separated values or sum of all In Sybase values. |
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| Text | Displays the text of the batch. |
The table below describes the information displayed in the Plan tab.
Table 7- 5 Batch entity Plan tabColumn Description
| Column | Description |
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| Launch icon to SQL |
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| tab | Launches into SQL tab. |
| Batch |
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| ID | Displays the batch ID. |
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| Database | Displays the database name. |
| Parsing |
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| User | Displays the parsing user name. |
| Most Recent |
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| Plan | Displays the date of the most recent plan. |
| Last Show |
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| Plan | Displays the date of the last shown plan. |
| Total Estimate |
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| Cost | Displays a graph/number. |
| Table |
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| Scan | Displays Yes or No. |
| Clustered Index |
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| Scan | Displays Yes or No. |
| Clustered Index |
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| Seek | Displays Yes or No. |
| Index |
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| Scan | Displays Yes or No. |
| Index |
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| Seek | Displays Yes or No. |
| Table |
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| Lookup | Displays Yes or No. |
| Sort |
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| Displays Yes or No. |
| Merge |
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| Join | Displays Yes or No. |
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| Join | Displays Yes or No. |
| Nested Loop |
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| Join | Displays Yes or No. |
| Parallel |
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| Access | Displays Yes or No. |
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It is possible to use the Objects tab to identify performance problems by:
- See Examining an object's space usage over time on page 80.
- See Examining fragmentation of table data and indexes on page 80.
- See Examining distribution statistics of indexes and columns on page 80.
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Space usage information, collected by the Collect Space Utilization process, lets you examine the space allocated versus the space used, in a table and index. This enables you to easily keep track of object growth over time and decide how to spread database segments over various devices and how to connect objects to segments in the specified database.
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Fragmentation of table data and indexes may affect the performance of your system. The fragmentation occurs as a result of data modification (INSERT, UPDATE, and DELETE statements) performed on the table. Fragmentation increases the amount of page reads performed by the query, increasing their resource consumption.
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- Use the Optdiag view in the Table or Index entity to observe fragmentation information.
- Determine whether the table or index is heavily fragmented and needs to be reorganized. See For more information about table and view entities, see About the Table entity and Tables Contain Same Column entity on page 69.
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- and About the View entity and Views Contain Same Column entity
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Density and selectivity statistics of an index can help you determine whether or not the index is useful to the query optimizer. The information displayed in the Statistics view of the Index entity indicates the selectivity of an index; the more selective an index is, the more useful it is, because this means more rows can be eliminated from consideration. You can also determine what columns in the index contribute to the selectivity and thus decide whether all should be included in the index.
To examine distribution statistics of indexes and columns, use the Statistics view of the Column entity to help you see the distribution of values in that column. See For more information about viewing these statistics, see About viewing density and selectivity statistics on page 73.See and About viewing column statistics on page 73.
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