How to Locate the Optimizer Statistics for a Partitioned Table or Index
Last updated on NOVEMBER 16, 2017
Applies to:Oracle Database - Enterprise Edition - Version 126.96.36.199 and later
Information in this document applies to any platform.
This document explains how to locate optimizer statistics for a partitioned table or index within the data dictionary.
Since a given data dictionary view only contains information on one type of statistic, it can be difficult to locate optimizer statistics information across all the various data dictionary views. The cost-based optimizer, as input, uses statistics on tables, (sub)partitions, columns, and indices.
When dealing with a partitioned table, it is also important to understand what type of physical segments are created (i.e., the segment actually consumes physical space on disk), and what other types are merely logical in nature.
- When you create a partitioned table, there is no table segment created on disk - only partition segments are created. The table is simply a logical concept.
- When you create a composite-partitioned table, no table segment or partition segments exist - only subpartition segments. Again, the table and partition layers are logical concepts and do not consume any space on disk.
Please be aware that optimizer statistics stored within the data dictionary on partitioned tables will include some rows which represent a segment, and others which represent only a logical entity. However, the fact that the stats do not represent a space-consuming item does not make them any less valuable to the cost-based optimizer.
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