3 Setting Up a Caching Infrastructure

TimesTen Application-Tier Database Cache environment variables for UNIX

The shared library search path environment variable such as LD_LIBRARY_PATH or SHLIB_PATH must include the TimesTen_install_dir/lib directory.

For more information, see "Shared library path environment variable" in Oracle TimesTen In-Memory Database Installation Guide.

The PATH environment variable must include the TimesTen_install_dir/bin directory.

In the following example, TimesTen is installed in the /timesten/myinstance directory:

LD_LIBRARY_PATH=/timesten/myinstance/lib
PATH=/timesten/myinstance/bin

TimesTen Application-Tier Database Cache environment variables for Microsoft Windows

The PATH system environment variable must include the following directories:

• Oracle_install_dir\bin

• TimesTen_install_dir\lib

• TimesTen_install_dir\bin

In the following example, Oracle Database is installed in the C:\oracle\ora112 directory and TimesTen is installed in the C:\timesten\myinstance directory:

PATH=C:\oracle\ora112\bin;C:\timesten\myinstance\lib;C:\timesten\myinstance\bin

Create the Oracle database users

You must create a default tablespace and a user timesten that is to own the Oracle Database tables that store information about cache operations.

Create or designate a default tablespace for the timesten user, which is passed as an argument to the initCacheGlobalSchema.sql script. This tablespace is used for storing TimesTen Application-Tier Database Cache management objects that should not be shared with other applications. While you may also store Oracle base tables that are cached in TimesTen, we strongly recommend that this tablespace be used solely by TimesTen for cache management.

Execute the SQL*Plus script TimesTen_install_dir/oraclescripts/initCacheGlobalSchema.sql, which creates:

• The timesten user

• The Oracle Database tables owned by the timesten user to store information about the cache environment, including a cache grid if one is configured

• The TT_CACHE_ADMIN_ROLE role that defines privileges on these Oracle Database tables

See "Managing a caching environment with Oracle Database objects" for a list of Oracle Database tables owned by the timesten user.

% cd TimesTen_install_dir/oraclescripts
% sqlplus sys as sysdba
Enter password: password
SQL> CREATE TABLESPACE cachetblsp DATAFILE 'datfttuser.dbf' SIZE 100M;
SQL> @initCacheGlobalSchema "cachetblsp"

Create or designate one or more users to own Oracle Database tables that are to be cached in a TimesTen database. These users are the schema users. These may be existing users or new users. The tables to be cached may or may not already exist.

SQL> CREATE USER oratt IDENTIFIED BY oracle;

Next, you must create a user that creates, owns, and maintains Oracle Database objects that store information used to manage the cache environment (including a cache grid if one is configured) for a TimesTen database and enforce predefined behaviors of particular cache group types. We refer to this user as the cache administration user.

Designate the tablespace that was created for the timesten user as the default tablespace for the cache administration user. This user creates tables in this tablespace that are used to store information about the cache environment and its cache groups. Other Oracle Database objects (such change log tables, replication metadata tables, and triggers) are used to enforce the predefined behaviors of autorefresh cache groups and AWT cache groups are created in the same tablespace. To create and manage these objects, the cache administration user must have a high level of privileges.

See "Managing a caching environment with Oracle Database objects" for a list of Oracle Database tables and triggers owned by the cache administration user.

SQL> CREATE USER cacheuser IDENTIFIED BY oracle
  2  DEFAULT TABLESPACE cachetblsp QUOTA UNLIMITED ON cachetblsp;

Grant privileges to the Oracle database users

The cache administration user must be granted a high level of privileges depending on the cache group types created and the operations performed on these cache groups. You can run the SQL*Plus script TimesTen_install_dir/oraclescripts/grantCacheAdminPrivileges.sql as the sys user to grant the cache administration user the minimum set of privileges required to perform cache grid and cache group operations. For more information on this SQL script, see "Automatically create Oracle Database objects used to manage data caching".

The entire list of privileges required for this user for each cache operation are listed in the first column of Table A-1 that is detailed in "Required privileges for the cache administration user and the cache manager user".

Automatically create Oracle Database objects used to manage data caching

TimesTen can automatically create Oracle Database objects owned by the cache administration user, such as cache and replication metadata tables, change log tables, and triggers when particular cache environment, cache group, and cache grid operations are performed. Some of these objects are used to store information about TimesTen databases that are associated with a particular cache grid. Other objects are used to enforce the predefined behaviors of autorefresh cache groups and AWT cache groups.

These Oracle Database objects are automatically created if the cache administration user has been granted the required privileges by running the SQL*Plus script TimesTen_install_dir/oraclescripts/grantCacheAdminPrivileges.sql as the sys user. The set of required privileges include CREATE SESSION, RESOURCE, CREATE ANY TRIGGER, and the TT_CACHE_ADMIN_ROLE role. The cache administration user name is passed as an argument to the grantCacheAdminPrivileges.sql script.

In addition to the privileges granted to the cache administration user by running the grantCacheAdminPrivileges.sql script, this user may also need to be granted privileges such as SELECT or INSERT on the cached Oracle Database tables depending on the types of cache groups you create, and the operations that you perform on the cache groups and their cache tables. See Table A-1 for a complete list of privileges that need to be granted to the cache administration user in order to perform particular cache grid, cache group, and cache table operations.

SQL> @grantCacheAdminPrivileges "cacheuser"
SQL> exit

For example, with autorefresh cache groups, the Oracle Database objects used to enforce the predefined behaviors of these cache group types are automatically created if the objects do not already exist and one of the following occurs:

• The cache group is created with its autorefresh state set to PAUSED or ON.

• The cache group is created with its autorefresh state set to OFF and then altered to either PAUSED or ON.

Manually create Oracle Database objects used to manage data caching

The cache administration user requires the RESOURCE privilege to automatically create the Oracle Database objects used to:

• Store information about TimesTen databases that are associated with a particular cache environment, including a cache grid if one is configured.

• Enforce the predefined behaviors of autorefresh cache groups. In this case, the cache administration user also requires the CREATE ANY TRIGGER privilege to automatically create these Oracle Database objects.

• Enforce the predefined behaviors of AWT cache groups.

For security purposes, if you do not want to grant the RESOURCE and CREATE ANY TRIGGER privileges to the cache administration user required to automatically create the Oracle Database objects, you can manually create these objects.

To manually create the Oracle Database tables and triggers used to enforce the predefined behaviors of particular cache group types, run the SQL*Plus script TimesTen_install_dir/oraclescripts/initCacheAdminSchema.sql as the sys user. These objects must be created before you can create autorefresh cache groups and AWT cache groups. The cache administration user name is passed as an argument to the initCacheAdminSchema.sql script.

The initCacheAdminSchema.sql script also grants a minimal set of required privileges including CREATE SESSION and the TT_CACHE_ADMIN_ROLE role to the cache administration user. In addition to the privileges granted to the cache administration user by running the initCacheAdminSchema.sql script, this user may also need to be granted privileges such as SELECT or INSERT on the cached Oracle Database tables depending on the types of cache groups you create and the operations that you perform on the cache groups and their cache tables. See Table A-1 for a complete list of privileges that need to be granted to the cache administration user in order to perform particular cache grid, cache group, and cache table operations.

To manually create the Oracle Database tables used to store information about TimesTen databases that are associated with a particular cache grid, run the SQL*Plus script TimesTen_install_dir/oraclescripts/initCacheGridSchema.sql as the sys user. These tables must be created before you can create a cache grid. The cache administration user name and the name of the cache grid that you create are passed as arguments to the initCacheGridSchema.sql script.

SQL> @initCacheAdminSchema "cacheuser"
SQL> @initCacheGridSchema "cacheuser" "ttGrid"
SQL> exit

Other Oracle Database objects associated with Oracle Database tables that are cached in an autorefresh cache group are needed to enforce the predefined behaviors of these cache group types. See "Manually creating Oracle Database objects for autorefresh cache groups" for details about how to create these additional objects after you create the cache group.

To view a list of the Oracle Database objects created and used by TimesTen to manage the caching of Oracle Database data, execute the following query in SQL*Plus as the sys user:

SQL> SELECT owner, object_name, object_type FROM all_objects WHERE object_name 
  2  LIKE 'TT\___%' ESCAPE '\';

The query returns a list of tables, indexes, and triggers owned by either the timesten user or the cache administration user.

Define a DSN for the TimesTen database

A TimesTen database that caches data from an Oracle database can be referenced by either a system DSN or a user DSN. See "Managing TimesTen Databases" in Oracle TimesTen In-Memory Database Operations Guide for more information about creating TimesTen DSNs.

When creating a DSN for a TimesTen database that caches data from an Oracle database, pay special attention to the settings of the following connection attributes. All of these connection attributes can be set in a Data Manager DSN or a connection string, unless otherwise stated.

• PermSize specifies the allocated size of the database's permanent region in MB. Set this value to at least 32 MB.

• OracleNetServiceName must be set to the net service name of the Oracle database instance.

  On Microsoft Windows systems, the net service name of the Oracle database instance is specified in the Oracle Net Service Name field of the TimesTen Cache tab within the TimesTen ODBC Setup dialog box.

• DatabaseCharacterSet must be set to the Oracle database character set.

  You can determine the Oracle database character set by executing the following query in SQL*Plus as any user:

  SQL> SELECT value FROM nls_database_parameters
     2 WHERE parameter='NLS_CHARACTERSET';
  

• UID specifies the name of a cache user, such as the cache manager user, that has the same name as a companion Oracle Database user who can access the cached Oracle Database tables. The UID connection attribute can be specified in a Data Manager DSN, a client DSN, or a connection string.

• PWD specifies the password of the TimesTen user specified in the UID connection attribute. The PWD connection attribute can be specified in a Data Manager DSN, a client DSN, or a connection string.

• OraclePWD specifies the password of the companion Oracle Database user that has the same name as the TimesTen user specified in the UID connection attribute and can access the cached Oracle Database tables.

  Note:

  See "Create the TimesTen users" for more details on the cache manager user and its companion Oracle Database user.

• PassThrough can be set to control whether statements are to be executed in the TimesTen database or passed through to be executed in the Oracle database. See "Setting a passthrough level".

• LockLevel must be set to its default of 0 (row-level locking) because TimesTen Application-Tier Database Cache does not support database-level locking.

• TypeMode must be set to its default of 0 (Oracle Database type mode).

• ReplicationApplyOrdering and CacheAWTParallelism control parallel propagation of changes to TimesTen cache tables in an AWT cache group to the corresponding Oracle Database tables. See "Configuring parallel propagation to Oracle Database tables".

• CacheGridEnable configures whether you will create a cache grid to manage global cache groups. Set to 0 if you are not planning on using a cache grid; set to 1 if you are planning on using a cache grid.

[cachealone1]
DataStore=/users/OracleCache/alone1
PermSize=64
OracleNetServiceName=orcl
DatabaseCharacterSet=WE8ISO8859P1
CacheGridEnable=1

Create the TimesTen users

First, you must create a user who performs cache grid (if one is configured) and cache group operations. We refer to this user as the cache manager user. The TimesTen cache manager user must have the same name as a companion Oracle Database user that can access the cached Oracle Database tables. For example, the companion Oracle Database user must have privileges to select from and update the cached Oracle Database tables. The companion Oracle Database user can be the cache administration user, a schema user, or some other existing user. For ease of use, making the cache administration user be the companion Oracle Database user of the cache manager user is preferable; however, if you are concerned with the high level of privileges assigned to the cache administration user, then choose another Oracle Database user as the companion Oracle user. The password of the cache manager user can be different than the password of the companion Oracle Database user with the same name.

The cache manager user creates and configures the cache grid, if one is configured, and creates the cache groups. It may perform operations such as loading or refreshing a cache group although these operations can be performed by any TimesTen user that has sufficient privileges. The cache manager user can also monitor various aspects of the caching environment, such as the grid itself or asynchronous operations that are performed on cache groups such as autorefresh.

Then, you must create a user with the same name as an Oracle Database schema user for each schema user who owns or will own Oracle Database tables to be cached in the TimesTen database. We refer to these users as cache table users, because the TimesTen cache tables are to be owned by these users. Therefore, the owner and name of a TimesTen cache table is the same as the owner and name of the corresponding cached Oracle Database table. The password of a cache table user can be different than the password of the Oracle Database schema user with the same name.

Operations on a cache group or a cache table, such as loading a cache group or updating a cache table, can be performed by any TimesTen user that has sufficient privileges. In the examples throughout this guide, the cache manager user performs these types of operations although these operations can be performed by another user, such as a cache table user, that has the required privileges. If these operations are to be performed by a TimesTen user other than the cache manager user, the other user must have the same name as a companion Oracle Database user that can select from and update the cached Oracle Database tables. Connect to the TimesTen database specifying that user's name in the UID connection attribute, and supply the corresponding TimesTen and Oracle Database passwords in the PWD and OraclePWD connection attributes, respectively, to perform operations on a cache group or cache table.

% ttIsql cachealone1
Command> CREATE USER cacheuser IDENTIFIED BY timesten;
Command> CREATE USER oratt IDENTIFIED BY timesten;

Grant privileges to the TimesTen users

The privileges that the TimesTen users require depend on the types of cache groups you create and the operations that you perform on the cache groups. All of the privileges required for the TimesTen cache manager user for each cache operation are listed in the second column in Table A-1.

Command> GRANT CREATE SESSION, CACHE_MANAGER, CREATE ANY TABLE TO cacheuser;
Command> exit

Set the cache administration user name and password

You must set the cache administration user name and password in the TimesTen database before any cache grid or cache group operation can be issued with the ttCacheUidPwdSet built-in procedure. The cache agent connects to the Oracle database as this user to create and maintain Oracle Database objects that store information used to manage a cache grid and enforce predefined behaviors of particular cache group types. In addition, both the cache and replication agents connect to the Oracle database with the credentials set with the ttCacheUidPwdSet built-in procedure to manage Oracle database operations.

The cache administration user name and password need to be set only once in each TimesTen database that caches Oracle Database data unless it needs to be changed. For example, if you modify the password of the cache administration user, if the TimesTen database is destroyed and re-created, or if the cache administration user name is dropped and re-created in the Oracle database, the cache administration user name and password must be set again.

The cache administration user name cannot be changed if there are cache groups in the database. The cache groups must be dropped before you can drop and recreate the cache administration user. See "Changing cache user names and passwords" for more details.

% ttIsql "DSN=cachealone1;UID=cacheuser;PWD=timesten;OraclePWD=oracle"
Command> call ttCacheUidPwdSet('cacheuser','oracle');

It can also be set from a command line by running a ttAdmin -cacheUidPwdSet utility command as a TimesTen external user with the CACHE_MANAGER privilege:

% ttAdmin -cacheUidPwdSet -cacheUid cacheuser -cachePwd oracle cachealone1

If you do not specify the -cachePwd option, the ttAdmin utility prompts for the cache administration user's password.

For more information about the utility, see "ttAdmin" in Oracle TimesTen In-Memory Database Reference.

Managing data locally

If you are not planning to use global cache groups, you do not need to create a cache grid. In this case, set the CacheGridEnable connection attribute to 0, which can be configured in the DSN as described in "Define a DSN for the TimesTen database".

This connection attribute states that you will not use global cache groups. Once set, TimesTen does not require you to create a cache grid or associate the TimesTen database with the grid before cache groups can be created within that database.

With this option, you cannot create global cache groups within that database. If, at some point in the future, you decide to use global cache groups within a cache grid, perform the following:

1. Drop all existing cache groups.

2. Create the cache grid and associate the TimesTen in-memory database as a member, as described in "Overview of a cache grid".

3. Recreate all pre-existing cache groups.

See "Global cache groups" for more information about global cache groups.

Configuring a cache grid

An Oracle Database table cannot be cached in separate cache groups within the same TimesTen database. However, the table can be cached in separate cache groups within different TimesTen databases.

A TimesTen cache grid provides users with Oracle databases a means to horizontally scale out cache groups across multiple systems with read and write data consistency across the TimesTen databases and predictable latency for database transactions. A cache grid contains one or more grid members that collectively manage application data using the relational data model. A grid member is either a standalone TimesTen database or an active standby pair that consists of at least two replicated TimesTen databases.

Each database of a grid member is called a grid node. A node is a single TimesTen database that is either a standalone database, or the active database or standby database of an active standby pair. Therefore, a grid member is composed of one or two nodes.

Grid members can reside on the same system or on different systems. If the grid members reside across different systems, the systems must be connected to each other in a TCP/IP private network. Each system must have the same machine architecture, operating system version, platform, and bit version. The TimesTen major release number of all grid members must be the same.

A TimesTen database that is or is part of a grid member can contain local and global cache groups as well as explicitly loaded and dynamic cache groups.

A cache grid can be associated with only one Oracle database. A TimesTen database can be a member of only one cache grid. An Oracle database can be associated with more than one cache grid and each grid can be administered by a different cache administration user. A cache grid has no association with other cache grids.

The following sections describe the operations that must be performed on the TimesTen database by the cache manager user:

• Modify the PROCESSES system parameter for ten or more grid nodes

• Create a cache grid

• Associate a TimesTen database with a cache grid

PROCESSES >= 10*GridMembers + DLConnections + OraBackgroundProcesses

Command> call ttGridCreate('ttGrid');

Command> call ttGridNameSet('ttGrid');

Set a cache agent start policy

A cache agent start policy determines how and when the cache agent process starts on a TimesTen database. The cache agent start policy can be set to:

• manual

• always

• norestart

The default start policy is manual, which means the cache agent must be started manually by calling the ttCacheStart built-in procedure or running a ttAdmin -cacheStart utility command. To manually stop a running cache agent process, call the ttCacheStop built-in procedure or run a ttAdmin -cacheStop utility command.

When the start policy is set to always, the cache agent starts automatically when the TimesTen main daemon process starts. With the always start policy, the cache agent cannot be stopped when the main daemon is running unless the start policy is first changed to either manual or norestart. Then issue a manual stop by calling the ttCacheStop built-in procedure or running a ttAdmin -cacheStop utility command.

With the manual and always start policies, the cache agent automatically restarts when the database recovers after a failure such as a database invalidation. If the database was attached to a cache grid when the failure occurred, it is automatically reattached to the grid when the database recovers.

Setting the cache agent start policy to norestart means the cache agent must be started manually by calling the ttCacheStart built-in procedure or running a ttAdmin -cacheStart utility command, and stopped manually by calling the ttCacheStop built-in procedure or running a ttAdmin -cacheStop utility command.

With the norestart start policy, the cache agent does not automatically restart when the database recovers after a failure such as a database invalidation. You must restart the cache agent manually by calling the ttCacheStart built-in procedure or running a ttAdmin -cacheStart utility command. If the database was attached to a cache grid when the failure occurred, it is not automatically reattached to the grid when the database recovers. You must call the ttGridAttach built-in procedure to reattach the database to the grid.

Command> call ttCachePolicySet('always');

% ttAdmin -cachePolicy norestart cachealone1