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RC:Index Creation On 12.1.0.2 With Subpartitioning Much Bigger Than In 11g (Doc ID 2346052.1)

Last updated on FEBRUARY 27, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 12.1.0.2 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata 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.

Symptoms

We want to migrate an 11g Database to 12c on another server via Datapump.
The load via impdp was successful, but the index size with subpartition grows tremendously:

Size on 11g:

select sum(BYTES/1024/1024) from dba_segments where OWNER='<OWNER>' and SEGMENT_TYPE='INDEX SUBPARTITION' and SEGMENT_NAME='X2_RAW_MESSAGE_U';
SUM(BYTES/1024/1024)
--------------------
  494.0625


Size on 12c:

select sum(BYTES/1024/1024) from dba_segments where OWNER='<OWNER>' and SEGMENT_TYPE='INDEX SUBPARTITION' and SEGMENT_NAME='X2_RAW_MESSAGE_U';
SUM(BYTES/1024/1024)
--------------------
  10228.9375



To isolate the cause further tests were made. Duplicate and upgrade the database from 11g to 12c the index size remain small, but when the indexes were dropped and recreated the index grows
like with impdp. So the problem is not the datapump, but the creation of the index (same statement and same data: 11g (500MB) 12c (10220MB) )
Find attached the ddl for the index creation (create_index_X2_RAW_MESSAGE_U.sql)

Changes

 

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References


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