Static Subsystem

Full DBEFileSets

A transaction fails if it attempts to insert a row into a table whose DBEFileSet is full. To prevent this, you should monitor DBEFileSet capacity on a regular basis. The Static DBEFile screen displays the capacity of each DBEFile and DBEFileSet in a DBEnvironment. In the following Static DBEFile screen, the InvoiceFS DBEFileSet is 92% full. It contains only 12 pages and should be expanded.

You can plan for capacity by monitoring the growth of DBEFileSets and the database objects contained within them.

Poorly Clustered Indexes

A poorly clustered index forces ALLBASE/SQL to access more physical pages during index scans. Performance degrades because I/O increases. Applications that frequently access rows in index order perform better if the rows are physically stored together on disk in index order.

To check the clustering of an index, go to the Static Cluster screen. In the following example, the CCOUNT of the InvoiceIndex is approximately equal to the number of rows in the table, which indicates that the data is poorly clustered.

If this index is used frequently to access rows, you should unload the PurchDB.Invoice table in sorted order and reload it with ISQL. For more information, see the section "Clustering Indexes" in the chapter "Guidelines on Logical and Physical Design."

Indirect Rows

Avoid indirect rows, because they waste disk space and increase the amount of I/O needed to access data. Use the Static Indirect screen to detect the presence of indirect rows. On the screen that follows, the PurchDB.Invoice table has 12% indirect rows. For instructions on how to remove indirect rows, see "Unloading and Reloading to Remove Indirect Rows" in the chapter "Guidelines on Logical and Physical Design."

Hash Overflow Pages

As the number of hash overflow pages grows, the amount of I/O necessary to obtain table data increases. To monitor the overflow pages of a hash structure, access the Static Hash screen. In the next example, the PurchDB.Invoice table has seven overflow pages, and should be unloaded and reloaded to improve performance.

For instructions, see "Unloading and Reloading to Remove Overflow Pages" in the chapter "Guidelines on Logical and Physical Design."