Using Variables in the Oracle BI Repository 18-7
only occur on cache entries that included and matched all security-sensitive variables.
5. Use the Initialization Block list to select an initialization block that will be used to
refresh the value on a continuing basis.
To create a new initialization block, click New. See Creating Initialization Blocks
for more information.
6. To add a Default Initializer value, type the value in the Default Initializer box, or
click the Expression Builder button to use Expression Builder. 7.
Click OK.
Working with Initialization Blocks
Initialization blocks are used to initialize dynamic repository variables, system session variables, and nonsystem session variables. For example, the NQ_SYSTEM initialization
block is used to refresh system session variables.
This section contains the following topics:
■
About Using Initialization Blocks with Variables
■
Creating Initialization Blocks
■
Associating Variables with Initialization Blocks
■
Establishing Execution Precedence
■
When Execution of Session Variable Initialization Blocks Cannot Be Deferred
■
Enabling and Disabling Initialization Blocks
About Using Initialization Blocks with Variables
An initialization block contains the SQL statement that will be executed to initialize or refresh the variables associated with that block. The SQL statement must reference
physical tables that can be accessed using the connection pool specified in the Connection Pool
field in the Initialization Block dialog. If you want the query for an initialization block to have database-specific SQL, you can
select a database type for that query. If a SQL initialization string for that database type has been defined when the initialization block is instantiated, this string is used.
Otherwise, a default initialization SQL string is used.
This section contains the following topics:
■
Initializing Dynamic Repository Variables
■
Initializing Session Variables
Caution: By default, when you open the Initialization Block dialog
for editing in online mode, the initialization block object is automatically checked out. While the initialization block is checked
out, the Oracle BI Server may continue to refresh the value of dynamic variables refreshed by this initialization block, depending on the
refresh intervals that are set. When you check in the initialization block, the value of the dynamic variables is reset to the values shown
in the Default initializer. If you do not want this to occur, use the Undo Check Out
option.
18-8 Metadata Repository Builders Guide for Oracle Business Intelligence Enterprise Edition
■
About Row-Wise Initialization
Initializing Dynamic Repository Variables
The values of dynamic repository variables are set by queries defined in the Default initialization string
field of the Initialization Block dialog. You also set up a schedule that the Oracle BI Server will follow to execute the query and periodically refresh the
value of the variable. If you stop and restart the Oracle BI Server, the server automatically executes the SQL statements in repository variable initialization blocks,
reinitializing the repository variables.
The Oracle BI Server logs all SQL queries issued to retrieve repository variable information in nqquery.log when the logging level for the administrator account set
upon installation is set to 2 or higher. You should set the logging level to 2 for the administrator to provide the most useful level of information. You can find the
nqquery.log file in:
ORACLE_INSTANCE \diagnostics\logs\OracleBIServerComponent\coreapplication_obisn
For more information about user-level logging, see Managing the Query Log in Oracle Fusion Middleware System Administrators Guide for Oracle Business Intelligence
Enterprise Edition.
Initializing Session Variables
As with dynamic repository variables, session variables obtain their values from initialization blocks. Unlike dynamic repository variables, session variables are not
updated at scheduled time intervals. Instead, the Oracle BI Server creates new instances of those variables whenever a user begins a new session. The values remain
unchanged for the duration of the session.
Execution of session variable initialization blocks during session logon can be deferred until their associated session variables are actually accessed within the session. See
Creating Initialization Blocks for more information.
The Oracle BI Server logs all SQL queries issued to retrieve session variable information if the logging level is set to 2 or higher in the Identity Manager User
object, or the LOGLEVEL system session variable is set to 2 or higher in the Variable Manager.
The default location for the nqquery.log file is: ORACLE_INSTANCE
\diagnostics\logs\OracleBIServerComponent\coreapplication_obisn For more information about user-level logging, see Managing the Query Log in
Oracle Fusion Middleware System Administrators Guide for Oracle Business Intelligence Enterprise Edition.
About Row-Wise Initialization
You can use the row-wise initialization option to create session variables dynamically and set their values when a session begins. The names and values of the session
variables reside in an external database that you access through a connection pool. The variables receive their values from the initialization string that you type in the
Initialization Block dialog.
For example, suppose you want to create session variables using values contained in a table named RW_SESSION_VARS. The table contains three columns:
■
USERID, containing values that represent the unique identifiers of the users
Using Variables in the Oracle BI Repository 18-9
■
NAME, containing values that represent session variable names
■
VALUE, containing values that represent session variable values Table 18–2
shows the table in this example.
To use row-wise initialization, create an initialization block and select the Row-wise initialization
option refer to Creating Initialization Blocks
. For this example, you would provide the following SQL statement for the initialization string:
SELECT NAME, VALUE FROM RW_SESSION_VARS
WHERE USERID=VALUEOFNQ_SESSION.USERID
Note that NQ_SESSION.USERID has already been initialized using another initialization block.
The following session variables would be created:
■
When John connects to the Oracle BI Server, his session contains two session variables from row-wise initialization: LEVEL, containing the value 4, and
STATUS, containing the value FULL_TIME.
■
When Jane connects to the Oracle BI Server, her session contains three session variables from row-wise initialization: LEVEL, containing the value 8; STATUS,
containing the value FULL-TIME; and GRADE, containing the value AAA.
Initializing a Variable with a List of Values You can also use the row-wise initialization option to initialize a variable with a list of values. You can then use the SQL IN
operator to test for values in a specified list.
For example, using the table values in the previous example, you would type the following SQL statement for the initialization string:
SELECT LIST_OF_USERS, USERID FROM RW_SESSION_VARS
WHERE NAME=STATUS AND VALUE=FULL-TIME
This SQL statement populates the variable LIST_OF_USERS with a list, separated by colons, of the values JOHN and JANE for example, JOHN:JANE. You can then use this
variable in a filter, as shown in the following WHERE clause:
WHERE TABLE.USER_NAME = valueofNQ_SESSION.LIST_OF_USERS The variable LIST_OF_USERS contains a list of values, that is, one or more values.
This logical WHERE clause expands into a physical IN clause, as shown in the following statement:
WHERE TABLE.USER_NAME IN JOHN, JANE
Table 18–2 Sample Session Variables Database Table
USERID NAME
VALUE JOHN
LEVEL 4
JOHN STATUS
FULL-TIME JANE
LEVEL 8
JANE STATUS
FULL-TIME JANE
GRADE AAA
18-10 Metadata Repository Builders Guide for Oracle Business Intelligence Enterprise Edition
Creating Initialization Blocks
See About Using Initialization Blocks with Variables
for more information about initialization blocks.
To create initialization blocks, perform the steps in the following sections:
■
Assigning a Name and Schedule to Initialization Blocks
■
Selecting and Testing the Data Source and Connection Pool
Assigning a Name and Schedule to Initialization Blocks
For repository variables, you can specify the day, date, and time for the start date, as well as a refresh interval.
To assign a name and schedule to initialization blocks: 1.
In the Administration Tool, select Manage, then select Variables. 2.
In the Variable Manager dialog, from the Action menu, choose New Repository or Session Initialization Block.
3.
In the [Repository|Session] Variable Initialization Block dialog, type a name for the block. The NQ_SYSTEM initialization block name is reserved.
4. Repository initialization blocks only In the Schedule area, select a start date and
