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This section includes the following topics:• About
- About the Objects tab
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- How the Objects tab is structured
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- About the entities you can examine in the Objects tab
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- How the Objects tab can help you identify performance problems
About the Objects tab
The Objects tab is a comprehensive browser, which allows you to understand the relationships and associations between database schema objects. It enables a more productive tuning process by reducing the need of another tool for exploring the Sybase catalog tables.
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The Main area shows comprehensive information on the selected entity. You can choose from several views to examine the entity from different angles. You can, for example, focus exclusively on Index Properties, Index Statistics, or Index Histograms.
About the Association area in the Objects tab
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The Objects tab displays information on different entities. This section provides an overview of all entities, their meaning, and their views.• About
- About the Instance entity
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- About the Database entity
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- About the Table entity and Tables Contain Same Column entity
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- About the Index entity
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- About viewing data storage and fragmentation information for the selected index
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- About the Column entity
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- About the View entity and Views Contain Same Column entity
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- About the User entity
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- About the Database Device entity
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- About the Segment entity
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- About the Data Cache entity
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- About the Unused Indexes entity
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- About the Statement entity
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- About the Batch entity
About the Instance entity
The Instance entity displays configuration information, and performance information, as collected by the Precise for Sybase Collector agent for the entire instance. The following views are available:• Overview
- Overview
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- Instance parameters
About getting an overview of instance configuration and performance information
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The Database entity displays configuration information, and performance information collected by the Precise for Sybase collector of the selected database. The following views are available:• Overview
- Overview
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- Database options
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- Replication Agent configuration parameter
About getting an overview configuration, performance, and Space Allocation information for a selected database
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This table describes the Replication Agent configuration parameters for the specified database. This view is only enabled for published databases. The Replication Agent Configuration Parameters in the Main area can be accessed as follows:1. In
- In the Objects tab in Precise for Sybase, select the desired database in the Association area.
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- Click Overview in the Main area, and then click Replication Agent Configuration Parameters. The Replication Agent Configuration Parameters appear in the Main area.
The headings in the Replication Agent Configuration Parameters main area are described below.
Table 7-1 Replication 1 Replication Agent Configuration Parameters headers
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The following views are available:• Overview
- Overview
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- Optdiag
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- Table partitions
About getting an overview of table entities
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Rows Displays the number of rows in the selected table during the selected time frame, as collected by the Collect Space Utilization process.
About viewing data storage and fragmentation information
The Optdiag view displays data storage and fragmentation information for the selected table. The following information is displayed:Optdiag Optdiag
- Optdiag. Optdiag displays the following information:
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- Pages. Displays the number of data pages.
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- Empty Pages. The number of empty data pages. A non-zero count, indicates fragmentation, which can be resolved with reorg.
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- Rows. The total number of data rows.
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- Number of forwarded records
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- . When there is not enough free space to write an updated record in its page, Sybase allocates the updated record to another page and instructs the old record to point to the new location. The number of forwarded records, is the number of records allocated to another page, since there was no free space in the original page. Accessing forwarded records adversely affects performance, because additional I/O is performed. Check the number of forwarded records in your table or index in relation to the total number of records. If the ratio is high, consider reorganizing the table or index to achieve a better performance. To reorganize data-only-locked tables, use the reorg command. This number is always zero for allpages-locked (APL) tables.
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- Deleted Rows. The number of committed deletes, whose space has not yet been reclaimed. An increase in this number means increase in fragmentation as well. This can be resolved using reorg.
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- Extents. Displays the number of extents used to store the data pages.
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- OAM + Allocation Page Counts
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- . The sum of Object Allocation Map (OAM) pages plus allocation pages for the table. An Object Allocation Map (OAM) shows how the Adaptive Server allocates space for objects. Each allocation page for an object has an entry in the OAM pages for that table or index. There is at least one OAM page per table.
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- First Extent Data Pages
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- . The number of pages that appear on the first extent in an allocation unit, and consequently share the extent with an allocation page. This number is useful for I/O estimation.
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- Min Record Size
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- . Indicates the minimum record size in the data pages.
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- Max Record Size
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- . Indicates the maximum record size in the data pages.
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- Avg Record Size
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- . Indicates the average record size in the data pages.
- Derived
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- Statistics. Derived Statistics displays the following information:
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- Average Extents Ratio. Ratio
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- of the size of the data to the size that can be stored in all pages allocated to the table. Gives an estimation of how full each page really is. Should be as close to 1.0 as possible. This statistic is only displayed in versions prior to version 12.5.0.3.
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- Data Page Cluster Ratio
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- . This is a measure of how well data pages are clustered within extents. The closer this number is to 1.0, the better. When the cluster ratio is low, then performance may be affected because it would take more I/O calls to read the table pages. This derived statistic is only displayed in version 12.5.0.3 and above.
- Table Definition Related
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- Values. Table Definition Related Values displays the following information:
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- Max Rows Per Page
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- . Value of max_rows_per_page table parameter. Setting a maximum number of rows per page can reduce contention for allpages-locked tables and indexes, as fewer rows are placed on each page.
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- Expected Row Size
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- . Value of the exp_row_size table definition parameter. Relevant for data-only-locked tables. Useful when an application allows rows that contain null values or short variable-length character fields to be inserted, and these rows grow in length with subsequent updates. The major purpose of setting an expected row size is to reduce row forwarding.
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- Reserved Page Gap
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- . Value of reservepagegap table definition parameter. The reservepagegap space management property is used to reserve empty pages for expansion, when additional pages need to be allocated. Setting this parameter can reduce the frequency of maintenance activities, such as record rebuild and re-creating indexes.
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- Extent Fragmentation (%)
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- . The extent fragmentation indicates how well the extents, which contain the data pages, are physically contiguous on the disk.
The page number of its first page identifies an extent. If the extents 8, 16, 24, or 32 make up an index, then we can see that the extents are contiguous on the disks, which means there are no gaps. On the other hand, if the extents 8, 24, 32, and 64 make up an index, then we can see that we have a gap. The extent fragmentation is computed by dividing the number of gaps by the number of extents, so in this example, the extent fragmentation is 1/4, or 25 percent.
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This number is not relevant to heaps because physical order has no importance in the data pages.
NOTE Derived statistics may show incorrect data, when table statistics are out-of-date. It is advised to run update statistics, before reviewing these figures.
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The Index entity displays general details regarding space utilization for the selected index. The following views are available:
• Overview
• OptdiagOptdiag
• Statistics
About getting an overview of index entities
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