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Materialized View With Fast Refresh (Doc ID 1093616.1)

Last updated on MARCH 12, 2021

Applies to:

Oracle Database Cloud Service - Version N/A and later
Oracle Database - Enterprise Edition - Version 10.2.0.4 to 11.2.0.2 [Release 10.2 to 11.2]
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Information in this document applies to any platform.

Symptoms

NOTE: In the images and/or the document content below, the user information and data used represents fictitious data from the Oracle sample schema(s) or Public Documentation delivered with an Oracle database product.  Any similarity to actual persons, living or dead, is purely coincidental and not intended in any manner. 

During the fast refresh of a join mview where the master tables are on a remote database, the recursive delete command on the mview container table performs a full table scan on each master table (or via index if there is any) even when just few rows are impacted.

That full scan on a big table (even via index) makes refresh slow.

DELETE FROM "TEST"."T1" SNA$
WHERE
"MAN_ROWID" IN

    (SELECT /*+ NO_MERGE HASH_SJ */ * FROM

       (SELECT CHARTOROWID("MAS$"."M_ROW$$") RID$

FROM 
"TEST"."MLOG$_TEST"@<dblink_name> "MAS$" WHERE "MAS$".SNAPTIME$$ > :1 )MAS$)


Rows Row Source Operation
------- --------------------------------------------------- 
0 DELETE T1 (cr=1 pr=0 pw=0 time=6097 us) 
1 HASH JOIN SEMI (cr=1 pr=0 pw=0 time=5929 us) 
3 INDEX FULL SCAN T1003 (cr=1 pr=0 pw=0 time=39 us)(object id 185118) 
1 REMOTE MLOG$_TEST (cr=0 pr=0 pw=0 time=4250 us)

For each table the mview is based on.

Changes

 

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References


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