DBMS_CUBE_ADVISE contains subprograms for evaluating cube materialized views to support log-based fast refresh and query rewrite.
This chapter contains the following topics:
See Also:
Oracle OLAP User's Guide for information about cube materialized viewsTable 43-1 Summary of DBMS_CUBE_ADVISE Subprograms
| Subprogram | Description |
|---|---|
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Evaluates the metadata of a cube materialized view and generates recommendations for constraints, SQL dimension objects, and materialized view logs to support a broad range of query rewrite and fast refresh opportunities. |
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Identifies the name of an exception log used in validated constraints generated by |
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Displays or suppresses diagnostic messages for |
This table function evaluates the metadata for a specified cube materialized view. It generates recommendations and returns them as a SQL result set. These SQL statements can be used to create constraints, SQL dimension objects, and materialized view logs that allow the broadest range of query rewrite transformations and log-based fast refresh of the cube materialized view.
DBMS_CUBE_ADVISE.MV_CUBE_ADVICE (
owner IN VARCHAR2 DEFAULT USER,
mvname IN VARCHAR2,
reqtype IN VARCHAR2 DEFAULT '0',
validate IN NUMBER DEFAULT 0)
RETURN COAD_ADVICE_T PIPELINED;
Table 43-2 MV_CUBE_ADVICE Function Parameters
| Parameter | Description |
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Owner of the cube materialized view |
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Name of the cube, such as |
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Type of advice to generate:
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Validation option:
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A table of type COAD_ADVICE_T, consisting of a set of rows of type COAD_ADVICE_REC. Table 43-3 describes the columns.
Table 43-3 MV_CUBE_ADVICE Return Values
| Column | Datatype | Description |
|---|---|---|
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Owner of the dimensional object identified in |
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Name of a cube enhanced with materialized view capabilities, such as |
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Owner of the relational object identified in |
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Name of the master table, such as |
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Type of recommendation:
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Pre-existing conditions that conflict with the recommendations and should be resolved before |
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SQL statement that implements the recommendation. |
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SQL statement that reverses Pre-existing conditions may prevent these statements from restoring the schema to its previous state. |
This function is available in Analytic Workspace Manager as the Materialized View Advisor, which will generate a SQL script with the recommendations.
You can query the returned rows the same as any other table, as shown in the example.
MV_CUBE_ADVICE generates unique object names each time it is called. You should execute the function once, capture the results, and work with those SQL statements.
Take care when dropping database objects. If a table already has a materialized view log, it will have the same name used in the SQL DROP MATERIALIZED VIEW LOG statement in the DROPTEXT column. You should avoid inadvertently dropping materialized view logs, especially when they may be used for remote data replication.
The following query displays the SQL statements recommended by MV_CUBE_ADVICE. UNITS_FACT is the master table for UNITS_CUBE, and MV_CUBE_ADVICE generates an ALTER TABLE command to add primary key constraints.
It also generates an ALTER MATERIALIZED VIEW command to compile the CB$UNITS_CUBE cube materialized view.
SQL> SELECT apiobject, sqlobject, sqltext
FROM TABLE(dbms_cube_advise.mv_cube_advice('GLOBAL', 'CB$UNITS_CUBE'));
APIOBJECT SQLOBJECT SQLTEXT
------------ --------------- ---------------------------------------------
UNITS_CUBE UNITS_FACT alter table "GLOBAL"."UNITS_FACT" add constra
int "COAD_PK000208" PRIMARY KEY ("CHANNEL_ID"
, "ITEM_ID", "SHIP_TO_ID", "MONTH_ID") rely d
isable novalidate
UNITS_CUBE CB$UNITS_CUBE alter materialized view "GLOBAL"."CB$UNITS_CU
BE" compile
This procedure identifies the name of an exception log used in validated constraints generated by MV_CUBE_ADVICE.
To create an exception log, use the utlexcpt.sql or the utlexpt1.sql script before executing SET_CNS_EXCEPTION_LOG.
The validate parameter of MV_CUBE_ADVICE must be set to 1.
The utlexcpt.sql script creates a table named EXCEPTIONS, and the SET_CNS_EXCEPTION_LOG procedure identifies it as the exception log for MV_CUBE_ADVICE. The ALTER TABLE statement now includes the clause VALIDATE EXCEPTIONS INTO "GLOBAL"."EXCEPTIONS".
SQL> @utlexcpt
Table created.
SQL> EXECUTE dbms_cube_advise.set_cns_exception_log;
PL/SQL procedure successfully completed.
SQL> SELECT apiobject, sqlobject, advicetype type, sqltext
FROM TABLE(
dbms_cube_advise.mv_cube_advice('GLOBAL', 'CB$UNITS_CUBE', '2', 1));
APIOBJECT SQLOBJECT TYPE SQLTEXT
------------ --------------- ---- ----------------------------------------------
UNITS_CUBE UNITS_FACT 2 alter table "GLOBAL"."UNITS_FACT" add constrai
nt "COAD_PK000219" PRIMARY KEY ("CHANNEL_ID",
"ITEM_ID", "SHIP_TO_ID", "MONTH_ID") norely en
able validate exceptions into "GLOBAL"."EXCEPT
IONS"
UNITS_CUBE CB$UNITS_CUBE 8 alter materialized view "GLOBAL"."CB$UNITS_CUB
E" compile
This procedure turns on and off diagnostic messages to server output for the MV_CUBE_ADVICE function.
The following example directs the diagnostic messages to server output. The SQL*Plus SERVEROUTPUT setting displays the messages.
SQL> SET SERVEROUT ON FORMAT WRAPPED
SQL> EXECUTE dbms_cube_advise.trace(1);
DBMS_COAD_DIAG: Changing diagLevel from [0] to [1]
PL/SQL procedure successfully completed.
SQL> SELECT sqlobject, sqltext, droptext
FROM TABLE(
dbms_cube_advise.mv_cube_advice('GLOBAL', 'CB$UNITS_CUBE'))
WHERE apiobject='UNITS_CUBE';
SQLOBJECT SQLTEXT DROPTEXT
--------------- ---------------------------------------- ----------------------------------------
UNITS_FACT alter table "GLOBAL"."UNITS_FACT" add co alter table "GLOBAL"."UNITS_FACT" drop c
nstraint "COAD_PK000222" PRIMARY KEY ("C onstraint "COAD_PK000222" cascade
HANNEL_ID", "ITEM_ID", "SHIP_TO_ID", "MO
NTH_ID") rely disable novalidate
CB$UNITS_CUBE alter materialized view "GLOBAL"."CB$UNI alter materialized view "GLOBAL"."CB$UNI
TS_CUBE" compile TS_CUBE" compile
20070706 07:25:27.462780000 DBMS_COAD_DIAG NOTE: Parameter mvOwner : GLOBAL
20070706 07:25:27.462922000 DBMS_COAD_DIAG NOTE: Parameter mvName : CB$UNITS_CUBE
20070706 07:25:27.462967000 DBMS_COAD_DIAG NOTE: Parameter factTab : .
20070706 07:25:27.463011000 DBMS_COAD_DIAG NOTE: Parameter cubeName : UNITS_CUBE
20070706 07:25:27.463053000 DBMS_COAD_DIAG NOTE: Parameter cnsState : rely disable novalidate
20070706 07:25:27.463094000 DBMS_COAD_DIAG NOTE: Parameter NNState : disable novalidate
20070706 07:25:27.462368000 DBMS_COAD_DIAG NOTE: Begin NN:
20070706 07:25:27.833530000 DBMS_COAD_DIAG NOTE: End NN:
20070706 07:25:27.833620000 DBMS_COAD_DIAG NOTE: Begin PK:
20070706 07:25:28.853418000 DBMS_COAD_DIAG NOTE: End PK:
20070706 07:25:28.853550000 DBMS_COAD_DIAG NOTE: Begin FK:
20070706 07:25:28.853282000 DBMS_COAD_DIAG NOTE: End FK:
20070706 07:25:28.853359000 DBMS_COAD_DIAG NOTE: Begin RD:
20070706 07:25:29.660471000 DBMS_COAD_DIAG NOTE: End RD:
20070706 07:25:29.661363000 DBMS_COAD_DIAG NOTE: Begin CM:
20070706 07:25:29.665106000 DBMS_COAD_DIAG NOTE: End CM:
SQL> EXECUTE dbms_cube_advise.trace(0);
DBMS_COAD_DIAG: Changing diagLevel from [1] to [0]
PL/SQL procedure successfully completed.