This document discusses materialized views in Oracle databases. It provides two main use cases: for aggregation, where a materialized view can speed up complex queries by pre-aggregating data, and for replication, where the same data can be made available across different database sites through materialized views. The document outlines some advantages like performance improvements, easy configuration, and mass deployment capabilities. It also covers considerations for using materialized views like data redundancy, storage needs, change management, and refresh options. Code examples are provided for creating materialized views and logs.

1. www.informatik-aktuell.de

2. Materialized Views
-
Praktischer Einsatz vor und in 12c

3. Company
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> 35 Consultants, Developers
> 15 years of know how
>

4. Know How
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5. Customers
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6. Contacts
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> jonas.gassenmeyer@syntegris.de
> sven.weller@syntegris.de

7. Let's do it!

8. What are MVs?
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> View: SQL is executed
> Materialized:
result set is stored in a table
> Legacy: snapshot (Oracle 8i)

9. Use case 1: Aggregation
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TableTab
leTable
slow complex select

10. Use case 1: Aggregation
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TableTab
leTable
slow complex select

11. Use case 1: Aggregation
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MV
runs at night runs on demand
TableTab
leTable
complex
SQL fast SQL

12. Use case 1: Aggregation
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MV
complex
SQL fast SQL
runs at night runs on demand
TableTab
leTable

13. Advantages
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> performance feature
> query rewrite
> easy confguration
(built-in Oracle feature)

14. Use case 2: Replication
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Local DB Master DBMV
Data
Database Link

15. Advantages
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> mass deployment (templates)
> site – specifc customization
(e.g. timing of refresh)
> connection only during refresh
> easy confguration
(built-in Oracle feature)

16. Real world example?

17. Chemical Substances
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> ordering vials/tubes/plates
difer on each site
> meta data about substances
same on each site

18. Chemical Substances
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> ordering vials/tubes/plates
difer on each site
> meta data about substances
same on each site
from ca. 40 Mio
aggregated to
ca. 6.5 Mio
ca. 18.5 Mio

19. Global Ordering
FrankfurtBoston
GUI
available amount,
concentration
format (plate/ tube)
MV MV

20. Frankfurt
(Master)
Tucson Paris ToulouseBoston
MV
PL/SQL
API
MVMVMV

21. Considerations
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> data redundancy
> additional storage
> (non-) currentness
> change management
(caching, drop & recreate?)
> update-able target
> SQL (connect by, distinct,
set operators,...)

22. Code?

23. Options
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SQL> CREATE MATERIALIZED VIEW mv_name
2 TABLESPACE TBS_NOLOG
3 BUILD DEFERRED
4 REFRESH COMPLETE ON DEMAND
5 DISABLE QUERY REWRITE
6 AS (
7 SELECT
8 ­–...
9 );

24. MVComplete refreshTable
COMPLETE REFRESH

25.
4 REFRESH COMPLETE FAST ON DEMAND
MV
Incremental refresh
Table
Incremental refresh
Incremental refresh
MV
LOG
FAST REFRESH

26.
4 REFRESH COMPLETE FAST ON DEMAND
MV
with
Data
complete refresh
create MV build deferred
Table
MV
empty
BUILD DEFERRED

27. atomic_refresh => true
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> MV is readable all the time
> Index maintenance per row
> REDO and UNDO
delete
INSERT
SELECT
MV
commit

28. atomic_refresh => false
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> tuncate is faster (High Water Mark)
> minimal Index maintenance
> direct path load
> no UNDO and less redo
> MV readable?
truncate
INSERT
/*+append*/
SELECT
MV
commit

29. Fast Refresh - Limits
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> Use ANSI Join Syntax
> Select ROWIDs when joining
> bulk load operations master table
INSERT /* +append */
SQL*Loader
INSERT ... SELECT * FROM

30. SQL> CREATE MATERIALIZED VIEW LOG
2 ON master
3 WITH PRIMARY KEY, ROWID
4 INCLUDING NEW VALUES;

31. SQL> CREATE MATERIALIZED VIEW LOG
2 ON master
3 WITH PRIMARY KEY, ROWID
4 INCLUDING NEW VALUES;
ROWID: reorganization / truncating of the master
will force a complete refresh

32. Change Management
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SQL> CREATE MATERIALIZED VIEW mv_name
2 TABLESPACE TBS_NOLOG
3 BUILD DEFERRED
4 REFRESH COMPLETE ON DEMAND
5 DISABLE QUERY REWRITE
6 AS (
7 SELECT
8 ­–...
9 );

33.
4 REFRESH COMPLETE FAST ON DEMAND
MViewRefresh
create
MV
prebuild
table
create table as select
Table
PREBUILD TABLE

34.
4 REFRESH COMPLETE FAST ON DEMAND
MView
RV$xxxx
tableRefresh
Table
Results show up
SQL
new Segment
OUT_OF_PLACE REFRESH

35. Enjoy the features but be careful!

36. Thank You!

37. Questions?
jonas.gassenmeyer@syntegris.de