IBM Books

Administration Guide

Visual Explain

Visual Explain can be used to study queries in more detail when compared to the other methods, especially those that contain more complex sequences of operations. Visual Explain is not available on all supported platforms. You should check the Quick Beginnings for your platform to see if Visual Explain is supported.

Visual Explain lets you view the access plan for explained SQL statements as a graph. You can use the information available from the graph to tune your SQL queries for better performance. Visual Explain also lets you dynamically explain a SQL statement and view the resulting access plan graph.

The optimizer chooses an access plan and Visual Explain displays the information as an access plan graph in which tables and indexes, and each operation on them, are represented as nodes, and the flow of data is represented by the links between the nodes.

To display an access plan graph, you must have created an explain snapshot. From an access plan graph, you can view the details for:

You can also use Visual Explain to:

For additional detail on Visual Explain, you should refer to the online information available through the Control Center. The Control Center can be accessed by typing db2cc on the command line.

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