Catalog Buffer Monitor 

Use

The database catalog buffer caches metadata about tables that have been recently accessed using Open SQL. A single catalog buffer instance exists for each used database schema. Although it is possible to register several DataSource objects for a particular database schema, the same catalog buffer is used for the schema.

You can use the Catalog Buffer Monitor to obtain statistics about the status and the use of the catalog buffer.

Prerequisites

You must have logged on to the Open SQL Monitors application as a J2EE Engine user from the administrator group.

Activities

To access the Catalog Buffer Monitor, follow the link CatalogBufferMonitor on the start page of the Open SQL Monitors application.

On the Accessed Catalog Buffers screen, you can choose a catalog buffer instance that you want to monitor. A catalog buffer is displayed along with the following details:

Catalog Buffer Details

Parameter Name	Description
Buffer ID	A unique identifier for a catalog buffer instance within a cluster node. It is created by the concatenation of the database host, the database name and the database schema.
Sync ID	A unique identifier of synchronization entries written to the BC_SYNCLOG table by the catalog buffer.
References	Current number of catalog readers associated to the catalog buffer instance
Max	Maximum number of entries in the buffer
Current	Current number of entries in the buffer
Free	Remaining free positions
Current Existence	Current number of entries in the existence buffer. The existence buffer stores information about table views that exist for the relevant DataSource.
Displacements	Number of displaced entries in the buffer

 

To view the details for a particular buffer, choose the relevant ID. The detailed view provides the following functions:

·        Refresh

Use this function to refresh the display of the catalog buffer contents.

·        Show Objects

Use this function to view all objects currently in the catalog buffer.

·        Show

Use this function to display a particular object from the catalog buffer. This option requires you to enter the name of the object. If it is not buffered, the function returns null.

·        Show existence

Use this function to check if an object is in the existence buffer. This option requires you to enter the name of the object. If it is not in the buffer, the function returns null.

·        Invalidate

Use this function to invalidate a particular object in the catalog buffer. This option requires you to enter the name of the object.

·        Reset

Use this function to remove all objects from the catalog buffer.

·        Back

Use this function to navigate back to the Accessed Catalog Buffers screen.

You can view and modify some of the catalog buffer parameters using the Offline Configuration Tool or the runtime screen of the Configuration Adapter Service in the Visual Administrator. You can find the property sheets for the catalog buffer of the relevant instance and DataSource under Configurations ® Open SQL.