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What could explain differences in space usage for tables and indexes that were moved from one database to another ? (Doc ID 1586058.1)

Last updated on SEPTEMBER 15, 2021

Applies to:

Oracle Database - Enterprise Edition - Version and later
Oracle Database Cloud Schema Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.


What could cause a significant difference in space usage between the space usage of tables and their associated indexes in a client environment (database A) and the space usage of the same objects in a server environment (database B) when tables from database A are copied over to database B via a database link and/or via an export & import operations ?

This note outlines the areas of RDBMS configuration which can affect the space usage of table data and index data.

Note that it is beyond the scope of this note to enumerate every specific combination of factors, but only to enumerate the main areas of configuration of an RDBMS environment which could account for a difference in space usage between two RDBMS instance environments that might be expected to use the same amount of space for tables of identical content.


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