Cache General Connection Attributes

Cache general connection attributes are only used when caching Oracle Database data.

The cache general connection attributes are described in detail next.

DynamicLoadEnable

This attribute enables or disables dynamic load of data from an Oracle database to a TimesTen dynamic cache group. By default, dynamic load of data from an Oracle database 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 or using the statement level optimizer hint TT_DynamicLoadEnable in a SQL statement.

Note:

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

Required Privilege

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

Usage in TimesTen Scaleout and TimesTen Classic

This attribute is supported in TimesTen Classic but not supported in TimesTen Scaleout.

Setting

Set DynamicLoadEnable as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX and Linux systems odbc.ini file in TimesTen Classic	DynamicLoadEnable	0 - Disables dynamic load of data from an Oracle database to TimesTen dynamic cache groups for the current connection. 1 (default) - Enables dynamic load of data from an Oracle database to TimesTen dynamic cache groups for the current connection.
Windows ODBC Data Source Administrator	Not applicable

DynamicLoadErrorMode

This attribute controls what happens when an application executes a SQL operation against a dynamic cache group and the SQL operation cannot use dynamic load.

With a value of 0, the SQL operation executes against whatever data is in the TimesTen tables and returns a result based on that data with no error indicated.

With a value of 1, any statement that cannot use dynamic load (even if it does not need dynamic load) fails with an error indicating that it is not dynamic load-compliant.

For more information on caching data from an Oracle database in a TimesTen cache group, see Dynamic Cache Groups in Oracle TimesTen In-Memory Database Cache Guide.

Note:

To override the value of this attribute at the statement level, set the DynamicLoadErrorMode optimizer flag with the ttOptSetFlag built-in procedure or using the statement level optimizer hint TT_DynamicLoadErrorMode in a SQL statement.

For details, see Statement Level Optimizer Hints in Oracle TimesTen In-Memory Database SQL Reference.

Required Privilege

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

Usage in TimesTen Scaleout and TimesTen Classic

This attribute is supported in TimesTen Classic but not supported in TimesTen Scaleout.

Setting

Set DynamicLoadErrorMode as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX and Linux systems odbc.ini file in TimesTen Classic	DynamicLoadErrorMode	0 (default) - Statements execute against the cached data with no error. 1 - Statements use dynamic load or fail with an error.
Windows ODBC Data Source Administrator	Not applicable

OracleNetServiceName

This attribute identifies the Service Name for the Oracle instance.

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

Required Privilege

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

Usage in TimesTen Scaleout and TimesTen Classic

This attribute is supported in TimesTen Classic but not supported in TimesTen Scaleout.

Setting

Set OracleNetServiceName as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX and Linux systems odbc.ini file in TimesTen Classic	OracleNetServiceName	Character string specifying the Oracle Service Name that is to be used as the Oracle ID.
Windows ODBC Data Source Administrator	Not applicable

OraclePWD

When using TimesTen for caching, the OraclePWD attribute is the password the Oracle cache administration user provides to connect to the Oracle database to perform cache operations. These cache operations include, for example, cache group SQL, passthrough, and ttLoadFromOracle.

For more information about cache group SQL operations, see Getting Started; for passthrough, see Setting a Passthrough Level in Oracle TimesTen In-Memory Database Cache Guide. For information about loading data from Oracle Database and using ttLoadFromOracle, see Use TimesTen Built-In Procedures to Recommend a Table and Load SQL Query Results in Oracle TimesTen In-Memory Database Operations Guide.

Notes:

• The name for the Oracle cache administration user must be the same as the TimesTen cache administration user.

• To specify the TimesTen cache administration user name, use UID.

• To specify the TimesTen cache administration password, use PWD.

• The value of the OraclePWD attribute can be different from the value specified for the PWD attribute.

Required Privilege

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

Usage in TimesTen Scaleout and TimesTen Classic

This attribute is supported in both TimesTen Classic and TimesTen Scaleout.

Setting

You can use the OraclePWD attribute to register an Oracle password in the connection string. However, we recommend you to store your passwords in a wallet. See Providing Cache Administration User Credentials When Connecting in Oracle TimesTen In-Memory Database Cache Guide.

If you decide to use the OraclePWD attribute to create an Oracle password, suppose you have defined the following odbc.ini file on Linux:

[myDSN]
Datastore=/data/myDSN
PermSize=512
TempSize=256
LogBufMB=256
LogFileSize=256
DatabaseCharacterSet=AL32UTF8
ConnectionCharacterSet=AL32UTF8
OracleNetServiceName=ttorcl

The example specifies OraclePWD as myoraclepwd for user cacheadmin by connecting to myDSN. The TimesTen cache administration password PWD is pwd. The Oracle cache administration user is not the instance administrator.

% ttisql
Copyright (c) 1996, 2022, Oracle. All rights reserved.
Type ? or "help" for help, type "exit" to quit ttIsql.

Command> connect"DSN=myDSN;UID=cacheadmin;PWD=mypwd;OraclePWD=myoraclepwd";
Connection successful:
DSN=myDSN;UID=cacheadmin;DataStore=/=/data/myDSN;DatabaseCharacterSet=AL32UTF8;
ConnectionCharacterSet=AL32UTF8;LogFileSize=256;LogBufMB=256;PermSize=512;
TempSize=256;OracleNetServiceName=ttorcl;(Default setting AutoCommit=1)

To connect using Windows, you must provide the OraclePWD in the connect string. The following example provides the cache administration user, the TimesTen cache administration user password and the Oracle cache administration user password.

ttIsql -connStr "DSN=database1CS;UID=cacheadmin;PWD=mypwd;OraclePWD=orapwd;"

In TimesTen Scaleout, this attribute can be set in a connectable or a connection string. See Connecting to a database in Oracle TimesTen In-Memory Database Scaleout User's Guide.

Also see

• PwdWallet
• ttUser
• UID and PWD

PassThrough

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 see Setting a Passthrough Level in the Oracle TimesTen In-Memory Database Cache 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 the Oracle database, use only TimesTen supported data types in column definitions. If the specified data type is not supported in TimesTen, the passthrough statement fails.

For information on changing the isolation level on the Oracle database connection, when using this attribute, see Isolation.

Required Privilege

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

Usage in TimesTen Scaleout and TimesTen Classic

This attribute is supported in both TimesTen Classic and TimesTen Scaleout.

Setting

Set PassThrough as follows.

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX and Linux systems odbc.ini file in TimesTen Classic	PassThrough	0 (default) - SQL statements are executed only on TimesTen. 1 - INSERT, UPDATE and DELETE statements are executed on TimesTen unless they reference one or more tables that are not in TimesTen. If they reference one or more tables not in TimesTen, they are passed through to the Oracle database. DDL statements are executed on TimesTen. Other statements are passed through to the Oracle database if they generate a syntax error in TimesTen or if one or more tables referenced within the statement are not in TimesTen. 2 - INSERT, UPDATE and DELETE statements performed on tables in read-only cache groups or user managed cache groups with the READONLY cache table attribute are passed through to the Oracle database. Passthrough behavior for other cache group types is the same as PassThrough=1. 3 - All statements are passed through to the Oracle database for execution.
Windows ODBC Data Source Administrator	Not applicable

Restrictions

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

• If the PassThrough attribute is set so that a query must be executed in the Oracle database, the query is sent to the Oracle database without any changes. If the query uses a synonym for a table in a cache group, then a synonym with the same name must be defined for the corresponding Oracle database table for the query to be successful.

• 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 the Oracle database.

• 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, or DELETE operations depends on the setting of the PassThrough attribute as described in the table above. TimesTen 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 database 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 database applications, the changes are never reflected in TimesTen.

• 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, passthrough execution of DDL statements does not result in commits on the TimesTen side.

• A transaction that contains operations that are replicated with RETURN TWOSAFE cannot have a PassThrough setting greater than 0. If PassThrough is greater than 0, an error is returned and the transaction must be rolled back.

• When PassThrough is set to 0, 1, or 2, the following behavior occurs when a dynamic load condition exists:

  • A dynamic load can occur for a SELECT operation on cache tables in any dynamic cache group type.

  • A dynamic load for an INSERT, UPDATE, or DELETE operation can only occur on cached tables with dynamic asynchronous or synchronous writethrough cache groups.

Refer to SQL Statements in Oracle TimesTen In-Memory Database SQL Reference for details about the INSERT, UPDATE, DELETE, and SELECT statements.

RACCallback

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

For more information, see Oracle TimesTen In-Memory Database Cache 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.

Usage in TimesTen Scaleout and TimesTen Classic

This attribute is supported in TimesTen Classic but not supported in TimesTen Scaleout.

Setting

Set RACCallback as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX and Linux systems odbc.ini file in TimesTen Classic	RACCallback	0 - Do not install TAF and FAN callbacks. 1 (default) - Install the TAF and FAN callbacks.
Windows ODBC Data Source Administrator	Not applicable

StandbyNetServiceName

This attribute identifies the Service Name for the standby Oracle instance from an Oracle Active Data Guard environment.

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

Required Privilege

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

Usage in TimesTen Scaleout and TimesTen Classic

This attribute is supported in TimesTen Classic but not supported in TimesTen Scaleout.

Setting

Set StandbyNetServiceName as follows:

Where to set the attribute	How the attribute is represented	Setting
C or Java programs or UNIX and Linux systems odbc.ini file in TimesTen Classic	StandbyNetServiceName	Character string specifying the Oracle Service Name that is to be used as the standby Oracle ID.
Windows ODBC Data Source Administrator	Not applicable