IMDB Cache connection attributes

IMDB Cache connection attributes are used only when you are using the IMDB Cache product. IMDB Cache attributes are listed in Table 1-7, "IMDB Cache connection attributes" and described in detail in this section.

CacheGridEnable

Determines whether cache grid is enabled or disabled. The TimesTen database must be a member of a cache grid before you can create cache groups. The default is 1 (enabled).

Required privilege

Only the instance administrator can change the value of this attribute.

Setting

Set CacheGridEnable as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX ODBC.INI file	CacheGridEnable	0 - Cache groups can be defined outside of a cache grid. 1 - All cache groups in the data store must be defined as members of a cache grid. (default)
Windows ODBC Data Source Administrator	Cache Grid Enable check box	unchecked - Cache groups can be defined outside of a cache grid. checked - All cache groups in the data store must be defined as members of a cache grid. (default)

CacheGridMsgWait

Specifies the number of seconds that an application waits for a message response from a remote member in a cache grid.

For more information on caching Oracle data in a TimesTen cache grid, see Oracle In-Memory Database Cache User's Guide.

Required privilege

No privilege is required to change the value of this attribute.

Setting

Set CacheGridMsgWait as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX ODBC.INI file	CacheGridMsgWait	Set to the number of seconds that TimesTen should wait for a cache grid message from a remote member. The default is 60 seconds.
Windows ODBC Data Source Administrator	Cache Grid Message Wait field	Set to the number of seconds that TimesTen should wait for a cache grid message from a remote member. The default is 60 seconds.

DynamicLoadEnable

This attribute enables or disables dynamic load of Oracle data to a TimesTen dynamic cache group. By default, dynamic load of Oracle data is enabled.

To enable or disable dynamic load at the statement level and temporarily override the setting of this attribute, set the DynamicLoadEnable optimizer flag with the ttOptSetFlag built-in procedure.

Note:

The value of this attribute overrides the dynamic load behavior of all dynamic cache groups for the current connection to the data store.

Required privilege

No privilege is required to change the value of this attribute.

Setting

Set DynamicLoadEnable as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX ODBC.INI file	DynamicLoadEnable field	0 - Disables dynamic load of Oracle data to TimesTen dynamic cache groups for the current connection. 1 - Enables dynamic load of Oracle data to TimesTen dynamic cache groups for the current connection. (default)
Windows ODBC Data Source Administrator	Dynamic Load Enable field	0 - Disables dynamic load of Oracle data to TimesTen dynamic cache groups for the current connection. 1 - Enables dynamic load of Oracle data to TimesTen dynamic cache groups for the current connection. (default)

DynamicLoadErrorMode

This attribute controls the output of error messages upon failure of a transparent load operation on a TimesTen dynamic cache group. It determines if a load failure occurs silently, or if an error is returned.

For more information on caching Oracle data in a TimesTen cache group, see Oracle In-Memory Database Cache User's Guide.

Note:

To override the value of this attribute at the statement level, set the DynamicLoadErrorMode optimizer flag with the ttOptSetFlag built-in procedure.

Required privilege

No privilege is required to change the value of this attribute.

Setting

Set DynamicLoadErrorMode as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX ODBC.INI file	DynamicLoadErrorMode	0 - Errors are not returned upon a transparent load failure for a dynamic cache group. (default) 1 - Transparent load failure errors for dynamic cache groups are shown.
Windows ODBC Data Source Administrator	DynamicLoadErrorMode field	0 - Errors are not returned upon a transparent load failure for a dynamic cache group. (default) 1 - Transparent load failure errors for dynamic cache groups are shown.

OracleNetServiceName

The OracleNetServiceName attribute is used with the IMDB Cache.

This attribute identifies the Service Name for the Oracle instance

To cache Oracle tables and enable communication with Oracle, you must specify an Oracle Service Name.

Required privilege

No privilege is required to change the value of this attribute.

Setting

Set OracleNetServiceName as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX ODBC.INI file	OracleNetServiceName	Character string specifying the Oracle Service Name that is to be used as the Oracle ID.
Windows ODBC Data Source Administrator	OracleNetServiceName field	Character string specifying the Oracle Service Name that is to be used as the Oracle ID.

OraclePWD

This attribute is used with IMDB Cache. It identifies the password for the user specified by UID to connect to the Oracle database to perform cache operations.

Required privilege

No privilege is required to set the value of this attribute.

Setting

This attribute must be set in the connection string. On Linux, suppose you have defined the following odbc.ini file:

[myDSN]
Datastore=/data/myDSN
PermSize=128
DatabaseCharacterSet=AL32UTF8
ConnectionCharacterSet=AL32UTF8

Set OraclePWD for user ttuser by connecting to myDSN as follows:

% ttisql
 
Copyright (c) 1996-2009, Oracle.  All rights reserved.
Type ? or "help" for help, type "exit" to quit ttIsql.
 
 
Command> connect "dsn=myDSN;OraclePWD=mypwd";
Connection successful: DSN=beta4;UID=ttuser;DataStore=/data/myDSN;DatabaseCharacterSet=AL32UTF8;
ConnectionCharacterSet=AL32UTF8;PermSize=128;TypeMode=0;
(Default setting AutoCommit=1)
Command>

On Windows, set OraclePWD in the connection string in the same way that it is set on Linux.

PassThrough

This attribute is used with the IMDB Cache.

It specifies which SQL statements are executed only in the cache database and which SQL statements are passed through to the Oracle database. For more information about the IMDB Cache, see Oracle In-Memory Database Cache User's Guide and "CREATE CACHE GROUP" in Oracle TimesTen In-Memory Database SQL Reference.

The execution of a prepared PassThrough command assumes that the schema of dependent objects in the Oracle database has not changed since the prepare. If the schema has changed the PassThrough command may cause unexpected results from the Oracle database.

When passing SQL statements through to Oracle, use only TimesTen supported data types in column definitions. If the specified data type is not supported in TimesTen, the passthrough statement fails.

Required privilege

No privilege is required to change the value of this attribute.

Setting

Set PassThrough as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX ODBC.INI file	PassThrough	0 - SQL statements are executed only against TimesTen. 1 - Statements other than INSERT, DELETE or UPDATE and DDL are passed through if they generate a syntax error in TimesTen or if one or more tables referenced within the statement are not in TimesTen. All INSERT, DELETE and UPDATE statements will be passed through if the target table cannot be found in TimesTen. DDL statements will not be passed through. 2 - Same as 1, plus any INSERT, UPDATE and DELETE statement performed on READONLY cache group tables is passed through. 3 - All SQL statements, except COMMIT and ROLLBACK are passed through. COMMIT and ROLLBACK are executed on both TimesTen and Oracle. PL/SQL statements are not passed through to Oracle. 4 - All SELECT statements on global cache groups tables that cannot use transparent load are executed on Oracle. 5 - Similar to PassThrough=4 behavior except that the SELECT statements are not passed through to the Oracle database for execution until all committed updates on cache tables in global cache groups by previous transactions within the connection have been propagated to Oracle.
Windows ODBC Data Source Administrator	PassThrough List	0 - SQL statements are executed only against TimesTen. 1 - Statements other than INSERT, DELETE or UPDATE and DDL are passed through if they generate a syntax error in TimesTen or if one or more tables referenced within the statement are not in TimesTen. All INSERT, DELETE and UPDATE statements will be passed through if the target table cannot be found in TimesTen. DDL statements will not be passed through. 2 - Same as 1, plus any INSERT, UPDATE and DELETE statement performed on READONLY cache group tables is passed through. 3 - All SQL statements, except COMMIT and ROLLBACK are passed through. COMMIT and ROLLBACK are executed on both TimesTen and Oracle. PL/SQL statements are not passed through to Oracle. 4 - All SELECT statements on global cache groups tables that cannot use transparent load are executed on Oracle. 5 - Similar to PassThrough=4 behavior except that the SELECT statements are not passed through to the Oracle database for execution until all committed updates on cache tables in global cache groups by previous transactions within the connection have been propagated to Oracle.

Where to set the attribute

How the attribute is represented

Setting

C or Java programs or UNIX ODBC.INI file

PassThrough

0 - SQL statements are executed only against TimesTen.

1 - Statements other than INSERT, DELETE or UPDATE and DDL are passed through if they generate a syntax error in TimesTen or if one or more tables referenced within the statement are not in TimesTen. All INSERT, DELETE and UPDATE statements will be passed through if the target table cannot be found in TimesTen. DDL statements will not be passed through.

2 - Same as 1, plus any INSERT, UPDATE and DELETE statement performed on READONLY cache group tables is passed through.

3 - All SQL statements, except COMMIT and ROLLBACK are passed through. COMMIT and ROLLBACK are executed on both TimesTen and Oracle. PL/SQL statements are not passed through to Oracle.

4 - All SELECT statements on global cache groups tables that cannot use transparent load are executed on Oracle.

5 - Similar to PassThrough=4 behavior except that the SELECT statements are not passed through to the Oracle database for execution until all committed updates on cache tables in global cache groups by previous transactions within the connection have been propagated to Oracle.

Windows ODBC Data Source Administrator

PassThrough List

0 - SQL statements are executed only against TimesTen.

2 - Same as 1, plus any INSERT, UPDATE and DELETE statement performed on READONLY cache group tables is passed through.

3 - All SQL statements, except COMMIT and ROLLBACK are passed through. COMMIT and ROLLBACK are executed on both TimesTen and Oracle. PL/SQL statements are not passed through to Oracle.

4 - All SELECT statements on global cache groups tables that cannot use transparent load are executed on Oracle.

Certain restrictions need to be considered when using the passthrough feature. They include:

In the case that a SQL statement that uses TimesTen only syntax is passed through to the Oracle database, TimesTen returns an error message that indicates the syntax is not supported in Oracle.
Execution of a prepared passthrough command assumes that the schema of dependent objects in the Oracle database have not changed after the prepare. If the schema has changed, unexpected results can occur.
TimesTen does not include a cache invalidation feature. TimesTen does not verify that the cached tables are up to date. When a query is syntactically correct in TimesTen and the cache contains all the tables referenced in the query, the query is executed in TimesTen regardless of whether the cache is up to date.
The passthrough of Oracle INSERT, UPDATE and DELETE operations depends on the setting of the PassThrough attribute as described in the table above. IMDB Cache cannot detect INSERT, UPDATE and DELETE operations that are hidden in a trigger or stored procedure. Therefore, TimesTen cannot enforce the passthrough rule on hidden operations.
You cannot pass PL/SQL blocks through to the Oracle database.
The effects of a passthrough INSERT, UPDATE or DELETE operation on a read-only cache group are only seen after the transaction is committed and after the next autorefresh operation is completed.
There is no mechanism to detect or block updates on an Oracle table that is cached in a TimesTen synchronous writethrough cache group. Whether the updates are made by statements passed through the cache or from other Oracle applications, the changes are never reflected in IMDB Cache.
Oracle Call Interface (OCI) does not support a mechanism to describe the binding type of the input parameters. Ensure that your application supplies the correct SQL types for passthrough statements. The ODBC driver converts the C and SQL types and presents the converted data and the SQL type code to TimesTen. TimesTen presents the information to OCI. The length of the input binding values is restricted to 4000 for LONG and LONG RAW types.
At all passthrough levels, if a transaction has passed any DDL or DML statements to the Oracle database, then commits and rollbacks are executed in both Oracle and TimesTen. Otherwise, they are executed only in TimesTen.

RACCallback

This attribute allows you to enable or disable the installation of Transparent Application Failover (TAF) and Fast Application Notification (FAN) callbacks when using Real Application Clusters (RAC) with IMDB Cache.

For more information about IMDB Cache, see Oracle In-Memory Database Cache User's Guide and "CREATE CACHE GROUP" in Oracle TimesTen In-Memory Database SQL Reference.

Required privilege

No privilege is required to change the value of this attribute.

Setting

Set RACCallback as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX ODBC.INI file	RACCallback	0 - Do not install TAF and FAN callbacks. 1 -Install the TAF and FAN callbacks. (default)
Windows ODBC Data Source Administrator	RACCallback check box	unchecked - Do not install TAF and FAN callbacks. checked - Install the TAF and FAN callbacks. (default).