7-6 Metadata Repository Builders Guide for Oracle Business Intelligence Enterprise Edition
To set up a physical display folder: 1.
In the Physical layer of the Administration Tool, right-click a physical database and select New Object, then select Physical Display Folder.
2.
In the Physical Display Folder dialog, type a name for the folder.
3. To add tables to the display folder, click Add. Then, in the Browse dialog, select
the fact or physical tables you want to add to the folder and click Select.
Alternatively, you can drag one or more physical tables to the display folder after you close the dialog.
4. Click OK.
Working with Physical Tables
This section explains how to work with physical table objects in the Physical layer of the Oracle BI repository.
Note that both physical tables from relational data sources and physical cube tables from multidimensional data sources both use the Physical Table table type. Many of
the tasks described in this section apply to both relational and multidimensional data sources. See also
Working with Multidimensional Sources in the Physical Layer for
additional information specific to multidimensional data sources. This section contains the following topics:
■
About Tables in the Physical Layer
■
About Physical Alias Tables
■
Creating and Managing Physical Tables and Physical Cube Tables
■
Creating and Managing Columns and Keys for Relational and Cube Tables
■
Viewing Data in Physical Tables or Columns
About Tables in the Physical Layer
A physical table is an object in the Physical layer of the Oracle BI repository that corresponds to a table in a data source. Metadata for physical tables is usually
imported from the data source. This metadata enables the Oracle BI Server to access the data source tables with SQL requests.
When you delete a physical table, all dependent objects are deleted for example, columns, keys, and foreign keys. When you delete a physical cube table, hierarchies
are also deleted. The deletion fails if an alias exists on the physical table.
In addition to importing data source tables into the Physical layer, you can create virtual physical tables in the Physical layer, using values in the Table Type field in the
Physical Table dialog. Creating virtual tables can provide the Oracle BI Server and the underlying data sources with the proper metadata to perform some advanced query
requests.
A virtual physical table can be a stored procedure, or a SELECT statement. A virtual physical table created from a SELECT statement is also called an opaque view. You can
Note: Deleting a table in a display folder deletes only the shortcut to
that object. When you delete a column in a display folder, however, the column is actually deleted.
Working with Physical Tables, Cubes, and Joins 7-7
define an opaque view, and then deploy it in your data source to create a deployed view. See
Deploying Opaque Views for more information.
Use the Table Type list in the General tab of the Physical Table dialog to specify the physical table object type.
Table 7–1 describes the available object types.
Table 7–1 Table Types for Physical Tables
Table Type Description
Physical Table Specifies that the physical table object represents a data source
table. This table type is used for both relational physical tables and multidimensional cube tables.
Stored Proc Specifies that the physical table object is a stored procedure.
When you select this option, you type the stored procedure in the text box. Requests for this table will call the stored
procedure.
For stored procedures that are data source-specific, select Use database specific SQL
. When you select this option, the
Database column displays supported data sources by brand,
with Default as the root. You can enter data source-specific initialization strings by selecting the database type on the left
and entering the corresponding string on the right. The initialization string for the Default option is run when the
queried database type does not have a corresponding database-specific string defined.
Stored procedures within an Oracle Database do not typically return result sets. Therefore, they cannot be initiated from
within Oracle Business Intelligence. You need to rewrite the procedure as an Oracle function, use it in a SELECT statement in
the Administration Tool initialization block, and then associate it with the appropriate Oracle BI Server session variables in the
Session Variables dialog.
The following example shows a SQL initialization string using the GET_ROLES function that is associated with the USER,
GROUP, and DISPLAYNAME variables. The function takes a user Id as a parameter and returns a semicolon-delimited list of
group names:
SELECT user_id, get_rolesuser_id, first_name || || last_name
FROM csx_security_table WHERE user_id = :USER and password = :PASSWORD
Select Specifies that the physical table object is a SELECT statement.
When you select this option, you type the SELECT statement in the text field, and you also need to manually create the table
columns. The column names must match the ones specified in the SELECT statement. Column aliases are required for
advanced SQL functions, such as aggregates and CASE statements.
Requests for this table will execute the SELECT statement.
For SELECT statements that are data source-specific, select Use database specific SQL
. When you select this option, the
Database column displays supported data sources by brand,
with Default as the root. You can enter data source-specific initialization strings by selecting the database type on the left
and entering the corresponding string on the right. The initialization string for the Default option is run when the
queried database type does not have a corresponding database-specific string defined.
This type of table is also called an opaque view. See Deploying
Opaque Views for more information.
7-8 Metadata Repository Builders Guide for Oracle Business Intelligence Enterprise Edition
About Physical Alias Tables
An alias table alias is a physical table that references a different physical table as its source called the original table. Alias tables can be an important part of designing a
Physical layer because they enable you to reuse an existing table more than once, without having to import it several times.
There are two main reasons to create an alias table:
■
To set up multiple tables, each with different keys, names, or joins, when a single data source table needs to serve in different semantic roles. Setting up alias tables
in this case is a way to avoid triangular or circular joins.
For example, an order date and a shipping date in a fact table may both point to the same column in the time dimension data source table, but you should alias the
dimension table so that each role is presented as a separately labeled alias table with a single join. These separate roles carry over into the business model, so that
Order Date and Ship Date are part of two different logical dimensions. If a single logical query contains both columns, the physical query uses aliases in the
SQL statement so that it can include both of them.
You can also use aliases to enable a data source table to play the role of both a fact table, and a dimension table that joins to another fact table often called a fan
trap.
■
To include best practice naming conventions for physical table names. For example, you can prefix the alias table name with the table type such as fact,
dimension, or bridge, and leave the original physical table names as-is. Some organizations alias all physical tables to enforce best practice naming conventions.
In this case, all mappings and joins are based on the alias tables rather than the original tables.
Alias table names appear in physical SQL queries. Using alias tables to provide meaningful table names can make SQL queries referencing those tables easier to read.
For example:
WITH SAWITH0 AS select sumT835.Dollars as c1
from FactsRevT835AllRevenueBilled Time Join
select distinct 0 as c1, D1.c1 as c2
from SAWITH0 D1
order by c1 In this query, the meaningful alias table name A11 Revenue Billed Time Join has
been applied to the terse original physical table name FACTSREV. In this case, the alias table name provides information about which role the table was playing each
time it appears in SQL queries.
Alias tables can have cache properties that differ from their original tables. To set different cache properties for an alias table, select the option Override Source Table
Caching Properties in the Physical Table dialog for the alias table. In alias tables,
columns cannot be added, deleted, or modified. Because columns are automatically synchronized, no manual intervention is required.
Synchronization ensures that the original tables and their related alias tables have the same column definitions. For example, if you delete a column in the original table, the
column is automatically removed from the alias table.
Working with Physical Tables, Cubes, and Joins 7-9
You cannot delete an original table unless you delete all its alias tables first. Alternatively, you can select the original table and all its alias tables and delete them at
the same time.
You can change the original table of an alias table, if the new original table is a superset of the current original table. However, this could result in an inconsistent
repository if changing the original table deletes columns that are being used. If you attempt to do this, a warning message appears to let you know that this could cause a
problem and lets you cancel the action. Running a consistency check identifies orphaned aliases.
When you edit a physical table or column in online mode, all alias tables and columns must be checked out. The behavior of online checkout uses the following conventions:
■
If an original table or column is checked out, all its alias tables and columns are checked out.
■
If an alias table or column is checked out, its original table and column are checked out.
■
The checkout option is available for online repositories if not read-only and for all original and alias tables and columns.
Alias tables inherit some properties from their original tables. A property that is proxied is a value that is always the same as the original table, and cannot be changed.
In other words, the proxied properties are the ones that are dimmed in the alias table dialog. If the original table changes its value for that particular property, the same
change is applied on the alias table.
The following is a list of the properties that are proxied:
■
Cacheable the inherited property can be overridden
■
Cache never expires and Cache persistence time the inherited properties can be overridden
■
Row Count
■
Last Updated
■
Table Type
■
External Db Specifications The following is list of the properties that are not proxied:
■
Name
■
Description
■
Display Folder Containers
■
Foreign Keys
■
Columns
■
Table Keys
■
Complex Joins
Note: Alias tables and original tables never share columns. Aliases
and original tables have distinctly different columns that alias each other.
7-10 Metadata Repository Builders Guide for Oracle Business Intelligence Enterprise Edition
■
Source Connection Pool
■
Polling Frequency
■
All XML attributes
Creating and Managing Physical Tables and Physical Cube Tables
Use the General tab of the Physical Table dialog to create or edit physical tables and physical cube tables in the Physical layer of the Administration Tool.
This section contains the following topics:
■
Creating or Editing Physical Tables
■
Creating Alias Tables
■
Setting Physical Table Properties for XML Data Sources
Creating or Editing Physical Tables
This section describes how to create or edit the general properties for a table, including both relational physical tables and physical cube tables.
To create a physical table or edit general properties for tables: 1.
In the Physical layer of the Administration Tool, perform one of the following steps:
– To create a physical table, right-click the physical database or physical catalog
and select New Object, then select Physical Table.
If your database object has physical schemas defined, right-click the physical schema and select New Physical Table.
– To create a physical cube table for a multidimensional data source, right-click
the physical database and select New Object, then select Cube Table.
– To edit an existing physical table, double-click the physical table object in the
Physical layer.
2.
In the Physical Table dialog, complete the fields using Table 7–2
as a guide.
Caution: It is strongly recommended that you import cube tables,
not create them manually.
Table 7–2 General Properties for Physical Tables
Property Description
Name The name of the physical table.
Table Type Physical Table values: Physical Table, Stored Proc stored
procedure, or Select. Physical Cube Table values: Physical Table or Select.
See Table 7–1
for more information.
Working with Physical Tables, Cubes, and Joins 7-11
Use Dynamic Name Select this option to use a session variable to specify the
physical table name, similar to catalog and schema objects. This option is available for non-multidimensional data source tables
when you select a table type of Physical Table.
You might want to choose this option if you have a multi-tenancy implementation and you want to define a
separate physical table name for each customer. Another example would be to select between primary and shadow tables
that are valid at different times in your ETL cycle. In both cases, you can assign session variables to dynamically select the
appropriate table.
Default Initialization String Use database specific SQL
For non-multidimensional data source tables not alias tables, this option appears if you choose a Table Type of Stored Proc or
Select
. For multidimensional data source tables, this appears if
you choose a Table Type of Select.
When you select this option, you can specify the data source and type the SQL statements.
See Table 7–1
for more information. Cacheable
Select this option to include the table in the Oracle BI Server query cache. Typically, you should select this option for tables
that do not need to be accessed in real time. When you select this option, the Cache persistence time settings
become active. Note that there are additional configuration settings that affect
the behavior of the query cache. See Configuring Query Caching in Oracle Fusion Middleware System Administrators
Guide for Oracle Business Intelligence Enterprise Edition for full information.
Cache never expires When you select this option, cache entries do not automatically
expire. This could be useful when a table is important to a large number of queries users might run. For example, if most of your
queries have a reference to an account object, keeping it cached indefinitely could actually improve performance rather than
compromise it.
Note that selecting this option does not mean that an entry always remains in the cache. Other invalidation techniques,
such as manual purging, LRU Least Recently Used replacement, metadata changes, or use of the cache polling table
can result in entries being removed from the cache.
Cache persistence time How long table entries should persist in the query cache, or in
other words, the cache expiration time. Setting a cache persistence time is useful for OLTP data sources
and other data sources that are updated frequently. For example, you could set this option refresh the underlying
physical tables daily for a particular dashboard.
If a query references multiple physical tables with different persistence times, the cache entry for the query exists for the
shortest persistence time set for any of the tables referenced in the query. This makes sure that no subsequent query gets a
cache hit from an expired cache entry.
For more information, see Troubleshooting Problems with Event Polling Tables in Oracle Fusion Middleware System
Administrators Guide for Oracle Business Intelligence Enterprise Edition.
Table 7–2 Cont. General Properties for Physical Tables
Property Description
7-12 Metadata Repository Builders Guide for Oracle Business Intelligence Enterprise Edition
Creating Alias Tables
To create an alias table, right-click an existing physical table and select New Object, then select Alias. You can also create aliases on opaque views and stored procedures.
Table 7–3 describes properties that are specific to alias tables. Refer to
Table 7–2 for
information about other table properties that are shared between physical tables and alias tables.
Setting Physical Table Properties for XML Data Sources
Use the XML tab to set or edit properties for an XML data source. The XML tab of the Physical Table dialog provides the same functionality as the XML tab of the
Connection Pool dialog. However, setting properties in the Physical Table dialog overrides the corresponding settings in the Connection Pool dialog. See
Setting Connection Pool Properties in the XML Tab
for more information.
About the Calc Scripts Tab for Essbase Data Sources
The Calc Scripts tab for Essbase data sources is reserved for a future release.
Creating and Managing Columns and Keys for Relational and Cube Tables
Each physical table and physical cube table in the Physical layer of the Administration Tool has one or more physical columns. You can use the Columns, Keys, and Foreign
Keys tabs in the Physical Table dialog to view, create new, and edit existing columns, keys, and foreign keys that are associated with the table.
The following list describes the buttons that appear in the tabs:
■
New. Lets you create a new object by opening the dialog that corresponds to the
tab.
■
Edit. When you select an object and then click Edit, the dialog that corresponds to
the tab appears. You can then edit the properties of the object.
■
Delete. Deletes the selected object.
This section contains the following topics: External name
Applies to physical cube tables from multidimensional data sources. The external name is the physical name that is used
when referencing the cube table in physical SQL queries. This value must reflect the external name defined in the data source.
Display Column For Essbase data sources only. See
Working with Essbase Data Sources
for more information. Hint
Available only for some data sources. See Using Hints
for more information.
Table 7–3 Properties Specific to Physical Alias Tables
Property Description
Source Table Applies to alias tables. Click Select to choose the original
physical table from which to create an alias table. Override Source Table
Caching Properties Option available for alias tables. When selected, the cacheable
properties become available and you can clear or select the appropriate options.
Table 7–2 Cont. General Properties for Physical Tables
Property Description
Working with Physical Tables, Cubes, and Joins 7-13
■
Creating and Editing a Column in a Physical Table
■
Specifying a Primary Key for a Physical Table
■
Deleting Physical Columns for All Data Sources
Creating and Editing a Column in a Physical Table
If the column is imported, the properties of the column are set automatically. The following list contains information about nullable and data type values for columns
imported into the Physical layer.
■
Nullable. Indicates whether null values are allowed for the column. If null values
can exist in the underlying table, you need to select this option. This allows null values to be returned to the user, which is expected with certain functions and
with outer joins. It is generally safe to change a non-nullable value to a nullable value in a physical column.
■
Type. Indicates the data type of the column. Use caution when changing the data
type. Setting the values to ones that are incorrect in the underlying data source might cause unexpected results. If there are any data type mismatches, correct
them in the repository or reimport the columns that have mismatched data types.
If you reimport columns, you also need to remap any logical column sources that reference the remapped columns. The data type of a logical column in the business
model must match the data type of its physical column source. The Oracle BI Server passes these logical column data types to client applications.
Longvarchar and longvarbinary data types are supported for writing complete Logical SQL statements into usage tracking tables for debugging purposes. They
are not supported for general-purpose queries, and cannot be displayed in Presentation Services. Use direct SQL utilities to access columns with these data
types.
Except when stated otherwise, the characteristics and behavior of a physical cube column are the same as for other physical columns.
To create or edit a physical column: 1.
In the Physical layer of the Administration Tool, perform one of the following steps:
– To create a physical column, right-click a physical table and select New
Object
, then select Physical Column. –
To create a physical cube column for a multidimensional data source, right-click a physical cube table and select New Object, then select Physical
Cube Column .
– To edit an existing physical column, double-click the physical column object in
the Physical layer.
2. In the Physical Column dialog, type a name for the physical column.
