Setting Up General Properties For Connection Pools

To set up general properties for connection pools
  1. In the Physical layer of the Administration Tool, right-click a database and choose New Object > Connection Pool, or double-click an existing connection pool.
    The following is an illustration of the General tab in the Connection Pool dialog box.

  2. In the Connection Pool dialog box, click the General tab, and then complete the fields using information in Table 8.
    Properties that are specific to a multidimensional data sources can be found in Table 9.
Table 8. Connection Pool General Properties
Field or Button
Call interface
The application program interface (API) with which to access the data source. Some databases may be accessed using native APIs, some use ODBC, and some work both ways. If the call interface is XML, the XML tab is available but options that do not apply to XML data sources are not available.
Data source name
The drop-down list shows the User and System DSNs configured on your system. A data source name that is configured to access the database to which you want to connect. The data source name needs to contain valid logon information for a data source. If the information is invalid, the database logon specified in the DSN will fail.
Enable connection pooling
Allows a single database connection to remain open for the specified time for use by future query requests. Connection pooling saves the overhead of opening and closing a new connection for every query. If you do not select this option, each query sent to the database opens a new connection.
Execute on Connect
Allows the Oracle BI Administrator to specify a command to be executed each time a connection is made to the database. The command may be any command accepted by the database. For example, it could be used to turn on quoted identifiers. In a mainframe environment, it could be used to set the secondary authorization ID when connecting to DB2 to force a security exit to a mainframe security package such as RACF. This allows mainframe environments to maintain security in one central location.
Execute queries asynchronously
Indicates whether the data source supports asynchronous queries.
Isolation level
For ODBC and DB2 gateways, the value sets the transaction isolation level on each connection to the back-end database. The isolation level setting controls the default transaction locking behavior for all statements issued by a connection. Only one of the options can be set at a time. It remains set for that connection until it is explicitly changed.
The following is a list of the options:
Committed Read. Specifies that shared locks are held while the data is read to avoid dirty reads. However, the data can be changed before the end of the transaction, resulting in non repeatable reads or phantom data.
Dirty Read. Implements dirty read (isolation level 0 locking). When this option is set, it is possible to read uncommitted or dirty data, change values in the data, and have rows appear or disappear in the data set before the end of the transaction. This is the least restrictive of the isolation levels.
Repeatable Read. Places locks on all data that is used in a query, preventing other users from updating the data. However, new phantom rows can be inserted into the data set by another user and are included in later reads in the current transaction.
Serializable. Places a range lock on the data set, preventing other users from updating or inserting rows into the data set until the transaction is complete. This is the most restrictive of the four isolation levels. Because concurrency is lower, use this option only if necessary.
Maximum connections
The maximum number of connections allowed for this connection pool. The default is 10. This value should be determined by the database make and model and the configuration of the hardware box on which the database runs as well as the number of concurrent users who require access.
NOTE:  For deployments with Intelligence Dashboard pages, consider estimating this value at 10% to 20% of the number of simultaneous users multiplied by the number of requests on a dashboard. This number may be adjusted based on usage. The total number of all connections in the repository should be less than 800. To estimate the maximum connections needed for a connection pool dedicated to an initialization block, you might use the number of users concurrently logged on during initialization block execution.
The name for the connection pool. If you do not type a name, the Administration Tool generates a name. For multidimensional and XML data sources, this is prefilled.
Parameters supported
If the database features table supports parameters and the connection pool check box property for parameter support is unchecked, special code executes that allows the Oracle BI Server to push filters (or calculations) with parameters to the database. The Oracle BI Server does this by simulating parameter support within the gateway/adapter layer by sending extra SQLPrepare calls to the database.
Assigns permissions for individual users or groups to access the connection pool. You can also set up a privileged group of users to have its own connection pool.
Require fully qualified table names
Select this check box, if the database requires it.
When this option is selected, all requests sent from the connection pool use fully qualified names to query the underlying database. The fully qualified names are based on the physical object names in the repository. If you are querying the same tables from which the physical layer metadata was imported, you can safely check the option. If you have migrated your repository from one physical database to another physical database that has different database and schema names, the fully qualified names would be invalid in the newly migrated database. In this case, if you do not select this option, the queries will succeed against the new database objects.
For some data sources, fully qualified names might be safer because they guarantee that the queries are directed to the desired tables in the desired database. For example, if the RDBMS supports a master database concept, a query against a table named foo first looks for that table in the master database, and then looks for it in the specified database. If the table named foo exists in the master database, that table is queried, not the table named foo in the specified database.
Shared logon
Select the Shared logon check box if you want all users whose queries use the connection pool to access the underlying database using the same user name and password.
If this option is selected, then all connections to the database that use the connection pool will use the user name and password specified in the connection pool, even if the user has specified a database user name and password in the DSN (or in user configuration).
If this option is not selected, connections through the connection pool use the database user ID and password specified in the DSN or in the user profile.
Timeout (Minutes)
Specifies the amount of time, in minutes, that a connection to the data source will remain open after a request completes. During this time, new requests use this connection rather than open a new one (up to the number specified for the maximum connections). The time is reset after each completed connection request.
If you set the timeout to 0, connection pooling is disabled; that is, each connection to the data source terminates immediately when the request completes. Any new connections either use another connection pool or open a new connection.
Use Multithreaded Connections
When the check box is select ed, Oracle BI Server terminates idle physical queries (threads). When not selected, one thread is tied to one database connection (number of threads = maximum connections). Even if threads are idle, they consume memory.
The parameter DB_GATEWAY_THREAD_RANGE in the Server section of NQSConfig.ini establishes when Oracle BI Server terminates idle threads. The lower number in the range is the number of threads that are kept open before Oracle BI Server takes action. If the number of open threads exceeds the low point in the range, Oracle BI Server terminates idle threads. For example, if DB_GATEWAY_THREAD_RANGE is set to 40-200 and 75 threads are open, Oracle BI Server terminates any idle threads. 

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