Validating an index

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(listings 8-3 through 8-8) In operational use, the unbalanced index report would be run whenever the DBA suspects that update activity may have unbalanced the indexes.

listing 8.3 The SQL*Plus script to generate the report for index_id1The main driver routine for reporting index_stats Rem © 1997 by Donald K.

Recall that the goal of partitioning clustering algorithms (Part @ref(partitioning-clustering)) is to split the data set into clusters of objects, such that: In this section, we’ll describe the two commonly used indices for assessing the goodness of clustering: the silhouette width and the Dunn index.

These internal measure can be used also to determine the optimal number of clusters in the data.

The Oracle ANALYZE INDEX xxx VALIDATE STRUCTURE SQL command can be used to validate the structure for the index.

This command creates a single row in a view called INDEX_STATS.

Just be sure that id1through id5are present in a common directory when starting id1

The silhouette plot displays a measure of how close each point in one cluster is to points in the neighboring clusters.

The script id1provides a method for getting a complete report for all indexes.

Since the index_stats view will only hold one row at a time, it is not easy to create a SQL*Plus routine that will produce a index_stats report for all of the indexes on a system.

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