1 Managing TimesTen Databases

Connecting using TimesTen ODBC drivers

TimesTen includes the following ODBC drivers:

• TimesTen Data Manager driver: A TimesTen ODBC driver for use with direct connect applications.

• TimesTen Client driver: A TimesTen Client ODBC driver for use with client/server applications.

TimesTen includes the following two versions of the Data Manager ODBC driver:

• Production: Use the production version of the TimesTen Data Manager driver for most application development and for all deployment.

• Debug: Use the debug version of the TimesTen Data Manager driver only if you encounter problems with TimesTen itself. This version performs additional internal error checking and is slower than the production version. On UNIX, the TimesTen debug libraries are compiled with the -g option to display additional debug information.

On Windows, the production version of the TimesTen Data Manager is installed by default. To install the debug version, choose Custom setup. To install the TimesTen Client driver, choose either Typical or Custom setup.

Table 1-1 lists the ODBC drivers for Windows:

On UNIX, depending on the options selected at install time, TimesTen may install the Client driver and both the production version and the debug version of the TimesTen Data Manager ODBC driver.

Table 1-2 lists the TimesTen ODBC drivers for UNIX platforms.

Connecting using the TimesTen JDBC driver and driver manager

JDBC enables Java applications to issue SQL statements to TimesTen and process the results. It is the primary interface for data access in the Java programming language. For TimesTen installations, JDBC is installed with the TimesTen Data Manager.

As shown in Figure 1-1, the TimesTen JDBC driver uses the ODBC driver to access TimesTen databases. For each JDBC method, the driver executes a set of ODBC functions to perform the appropriate operation. Since the JDBC driver depends on ODBC for all database operations, the first step in using JDBC is to define a TimesTen database and the ODBC driver that will access it on behalf of JDBC.

The TimesTen JDBC API is implemented using native methods to bridge to the TimesTen native API and provides a driver manager that can support multiple drivers connecting to separate databases. The JDBC driver manager in the DriverManager class keeps track of all JDBC drivers that have been loaded and are available to the Java application. The application may load several drivers and access each driver independently. For example, both the TimesTen Client JDBC driver and the TimesTen direct driver can be loaded by an application. Then, Java applications can access databases either on the local machine or a remote machine.

For a list of the Java functions supported by TimesTen, see the Oracle TimesTen In-Memory Database Java Developer's Guide.

Overview of user and system DSNs

DSNs are resolved using a two-tiered naming system, consisting of user DSNs and system DSNs, which are as follows:

• A user DSN can be used only by the user who created the DSN.

  • On Windows, user DSNs are defined from the User DSN tab of the ODBC Data Source Administrator.

  • On UNIX, user DSNs are defined in the file $HOME/.odbc.ini or in a file named by the ODBCINI environment variable. This file is referred to as the user ODBC.INI file.

  Although a user DSN is private to the user who created it, it is only the DSN, consisting of the character-string name and its attributes, that is private. The underlying database can be referenced by other users' user DSNs or by system DSNs.

  TimesTen supports data sources for both the TimesTen Data Manager and the TimesTen Client in the .odbc.ini file.

• A system DSN can be used by any user on the machine on which the system DSN is defined to connect to the TimesTen database.

  • On Windows, system DSNs are defined from the System DSN tab of the ODBC Data Source Administrator.

  • On UNIX, system DSNs are defined in the sys.odbc.ini file, which is referred to as the system ODBC.INI file.

    • In a non-root installation, the file is located in install_dir/info/sys.odbc.ini.

    • In a root installation, the file is located in /var/TimesTen/InstanceName/sys.odbc.ini or /var/TimesTen/sys.odbc.ini.

Defining DSNs for direct or client/server connections

DSNs are created to uniquely identify a database, whether local or remote. The following explains the type of DSN to use for either a direct or client/server connection:

• Data Manager DSN: A DSN that specifies a local database uses the TimesTen Data Manager ODBC driver, which is the direct driver. You can use either the production version or the debug version of the TimesTen Data Manager driver.

  A Data Manager DSN refers to a database using a path name and a filename prefix. The database path name specifies the directory location of the database and the prefix for the database, such as C:\data\chns\AdminDS or /home/chns/AdminDS.

  Note:

  This path name and prefix does not define a file name, but the name of the directory where the database is located and the prefix for all database files. The actual files used by the database append file suffixes, such as C:\data\chns\AdminDS.ds0 or /home/chns/AdminDS.log2.

  A Data Manager DSN that refers to a given TimesTen database must be defined on the same system on which the database resides. TimesTen creates dsName.resn files for each database. These files are used internally by TimesTen for maintaining logs.

  If multiple Data Manager DSNs refer to the same database, they must all use exactly the same database path name, even if some other path name identifies the same location. For example, you cannot use a symbolic link to refer to the database in one DSN and the actual path name in another DSN. On Windows, you cannot use a mapped drive letter in the database path name.

• Client DSN: A Client DSN specifies a remote database and uses the TimesTen Client. A Client DSN refers to a TimesTen database indirectly by specifying a hostname, DSN pair, where the hostname represents the server machine on which TimesTen Server is running and the DSN refers to a Server DSN that specifies the TimesTen database on the server host.

• Server DSN: A Server DSN is always defined as a system DSN and is defined on the server system for each database on that server that will be accessed by client applications. The format and attributes of a server DSN are very similar to those of a Data Manager DSN.

On UNIX, all user DSNs including both Client DSNs and Data Manager DSNs that are created by a specific user are defined in the same user ODBC.INI file. Similarly, all system DSNs are defined in the same system ODBC.INI file.

The following table indicates the types of DSN supported by TimesTen, whether to create a user or system DSN and the location of the DSN.

For more information about Client DSNs and Server DSNs, see "Working with the TimesTen Client and Server".

Connection attributes for Data Manager DSNs or Server DSNs

There are four types of TimesTen Data Manager DSN or Server DSN attributes:

• Data Store attributes are associated with a database when it is created and cannot be modified by subsequent connections. They can only be changed by destroying and re-creating the database.

  The following are some of the more popular data store attributes:

  • DataStore: Directory name and file name prefix of the database.

  • LogDir: Directory name of the database transaction log files. By default, the transaction log files reside in the checkpoint files directory. Placing the transaction log files and checkpoint files on different disks can improve system throughput.

  • DatabaseCharacterSet: Required character set specification that defines the storage encoding.

• First connection attributes are used when the TimesTen database is loaded into memory. Only the instance administrator can load a database with first connection attribute settings. By default, TimesTen loads an idle database, which is a database with no connections, into memory when a first connection is made to it. These attributes persist for all subsequent connections until the last connection to the database is closed. First connection attributes can be modified only when the TimesTen database is unloaded and then the instance administrator reconnects with different values for the first connection attributes.

  The following are some of the more popular first connection attributes:

  • PermSize: Configures the allocated size of the database's permanent partition. The permanent partition contains persistent database elements. Only the permanent partition is written to disk during a checkpoint operation.

  • TempSize: Configures the allocated size of the database's temporary partition. The temporary partition contains transient data generated when executing statements.

    Note:

    Your system must have sufficient main memory to accommodate the entire database. For more details on setting partition sizes, see "Specifying the size of a database".

• General connection attributes are set by each connection and persist for the duration of the connection. Each concurrent connection can have different values.

  Note:

  If you provide connection attributes in the connection string, this overrides the connection attributes set in the DSN. See "Connecting to a database using a connection string" for details.

  The user name and password can be specified within the general connection attributes in the DSN. When the user name is specified in the connection attributes for the DSN, this defines the user name to be used in the connection, whether using a direct or client/server connection. Any user configuration in the general connection attributes or on the connection string itself has precedence over the user name provided when initiating the connection, if different.

  If you do not set the user name/password general connection attributes, the user and password defaults to the operating system user who initiates the connection.

  The first connection to the TimesTen database can ONLY be initiated by the instance administrator. In this case, the user name/password fields in the connection string must be blank and the instance administrator should be the one initiating the first connection.

  When you initiate a client/server connection, the passwords sent for the connection are all encrypted by the client/server protocol. For external users, you provide only the user name, as the password is verified by the operating system.

• IMDB Cache attributes allow you to enter the Oracle Service Identifier for the Oracle instance from which data will be loaded into TimesTen.

On Windows, you specify attributes in the ODBC Data Source Administrator.

On UNIX, you specify attributes in the ODBC.INI file. Attributes that do not appear in the ODBC.INI file assume their default value.

Creating a Data Manager DSN on Windows

The following sections describe how to create a DSN on Windows:

• Specify the ODBC driver

• Specify the Data Manager DSN

• Specify the connection attributes

Specify the Data Manager DSN

On the Data Store tab of the TimesTen ODBC Setup dialog, specify a data source name (DSN), a database directory path and prefix, and a database character set. The database directory path cannot reference a mapped drive. See Figure 1-2.

Figure 1-2 Data Store tab

Description of "Figure 1-2 Data Store tab"

For an explanation of the DSN, database path and prefix, see "Specifying Data Source Names to identify TimesTen databases". For an explanation of database character sets, see "Choosing a database character set". The description field is optional.

Specify the connection attributes

Indicate the desired connection attributes under the First Connection, General Connection, and NLS Connection tabs of the TimesTen ODBC Setup dialog as shown in Figure 1-3, Figure 1-4,and Figure 1-5. In addition, if you are using IMDB Cache for Oracle, specify the connection attributes shown in Figure 1-6. If you are using a multithreaded client/server configuration, specify the connection attributes shown in Figure 1-7.

Note:

For a description of the connection attributes, see "Connection Attributes" in Oracle TimesTen In-Memory Database Reference.

Figure 1-3 First Connection Attributes

Description of "Figure 1-3 First Connection Attributes"

Figure 1-4 General Connection Attributes

Description of "Figure 1-4 General Connection Attributes"

Figure 1-5 NLS Connection Attributes

Description of "Figure 1-5 NLS Connection Attributes"

Figure 1-6 IMDB Cache Attributes

Description of "Figure 1-6 IMDB Cache Attributes"

Figure 1-7 Server Attributes

Description of "Figure 1-7 Server Attributes"

Figure 1-8 PL/SQL Attributes

Click OK when finished.

Creating a Data Manager DSN on UNIX

This section includes the following topics:

• Create a user or system ODBC.INI file

• Using environment variables in database path names

Setting up a temporary database

This example illustrates how to set up a temporary database. For information on temporary databases, see "Database overview".

On Windows, you can use the settings in the TimesTen ODBC Setup dialog to set up a temporary database. See Figure 1-9 and Figure 1-10.

Figure 1-9 Data Store tab

Description of "Figure 1-9 Data Store tab"

Figure 1-10 First Connection Attributes

Description of "Figure 1-10 First Connection Attributes"

To set up a temporary database on UNIX, create the following entries in your ODBC.INI file. For a list of drivers for all UNIX platforms, see the table in "Connecting using TimesTen ODBC drivers".

The text in square brackets is the data source name.

[TempDs]
Driver=install_dir/lib/libtten.so
DataStore=/users/robin/TempDs
#this is a temporary database
Temporary=1
#create database if it is not found
AutoCreate=1
#log database updates to disk
LogPurge=1
DatabaseCharacterSet=US7ASCII

Specifying PL/SQL connection attributes in a DSN

You can specify values for PL/SQL general connection attributes.

The following are some of the PL/SQL connection attributes:

• PLSCOPE_SETTINGS - Controls whether the PL/SQL compiler generates cross-reference information.

• PLSQL_OPTIMIZE_LEVEL - Sets the optimization level that is used to compile PL/SQL library units.

• PLSQL_MEMORY_ADDRESS - Specifies the virtual address, as a hexadecimal value, at which the PL/SQL shared memory segment is loaded into each process that uses the TimesTen direct drivers. This memory address must be identical in all connections to your database and in all processes that connect to your database.

• PLSQL_MEMORY_SIZE - Determines the size, in megabytes, of the PL/SQL shared memory segment.

This example creates the PLdsn DSN, enables PL/SQL by setting PLSQL to "1" and sets the PL/SQL shared memory segment size to 32 MB.

[PLdsn]
Datastore=/users/user1/PLdsn
PermSize=32
DatabaseCharacterSet=AL32UTF8
ConnectionCharacterSet=AL32UTF8
PLSQL=1
PLSQL_MEMORY_SIZE=32

For more examples, see "PL/SQL connection attributes" in Oracle TimesTen In-Memory Database PL/SQL Developer's Guide.

Creating multiple DSNs to a single database

You can create two or more DSNs that refer to the same database but have different connection attributes.

This example creates two DSNs, AdminDSN and GlobalDSN. The DSNs are identical except for their connection character sets. Applications that use the US7ASCII character set can connect to the TTDS database by using AdminDSN. Applications that use multibyte characters can connect to the TTDS database by using GlobalDSN.

For Windows, use the ODBC Data Source Administrator to define AdminDSN as shown in Figure 1-11. AdminDSN is created with the AL32UTF8 database character set. Figure 1-12 shows that US7ASCII is the connection character set for AdminDSN.

Figure 1-11 Creating AdminDSN using TTDS database

Description of "Figure 1-11 Creating AdminDSN using TTDS database"

Figure 1-12 Setting the connection character set for AdminDSN

Description of "Figure 1-12 Setting the connection character set for AdminDSN"

GlobalDSN is also created with the AL32UTF8 database character set, as shown in Figure 1-13. Figure 1-14 shows that the connection character set for GlobalDSN is AL32UTF8.

Figure 1-13 Creating GlobalDSN using TTDS database

Description of "Figure 1-13 Creating GlobalDSN using TTDS database"

Figure 1-14 Setting the connection character set for GlobalDSN

Description of "Figure 1-14 Setting the connection character set for GlobalDSN"

The next example shows how to specify the DSNs on UNIX. It uses the TimesTen Data Manager ODBC driver for Solaris.

The text in square brackets is the data source name.

[AdminDSN]
Driver=install_dir/lib/libtten.so
Datastore=/data/TTDS
DatabaseCharacterSet=AL32UTF8
ConnectionCharacterSet=US7ASCII

[GlobalDSN]
Driver=install_dir/lib/libtten.so
DataStore=/data/TTDS
DatabaseCharacterSet=AL32UTF8
ConnectionCharacterSet=AL32UTF8

ODBC Data Sources

Each entry in the optional ODBC Data Sources section lists a data source and a description of the driver it uses. The data source section has the following format:

[ODBC Data Sources]
DSN=driver-description

• The DSN is required and it identifies the data source to which the driver connects. You choose this name.

• The driver-description is required. It describes the driver that connects to the data source.

The optional Data Sources section, when present in the system DSN file on the TimesTen Server, is used during the setup of Client DSNs. All system DSNs are made available to the Client DSN setup for the ODBC Data Source Administrator on the client, which displays all available DSNs on the TimesTen Server. The user can always add a new system DSN in the ODBC Data Source Administrator. When adding DSNs to the system DSN file, you should only include those DSNs that can be advertised to clients. All system DSNs are potentially accessible through the client/server configuration, even if they are not advertised.

DSN specification

Each DSN listed in the ODBC Data Sources section has its own DSN specification. The DSN specification for Data Manager DSN has the format shown in Table 1-3.

For example, the sampledb_1121 DSN could have a specification that includes the following:

[sampledb_1121]
Driver=install_dir/lib/libtten.so
DataStore=install_dir/info/DemoDataStore/sampledb_1121
...

The database specification for TimesTen Client DSN has the format shown in Table 1-4.

For example, the client/server data source sampledbCS_1121 that connects to sampledb_1121 on the TimesTen Server ttserver could have a data source specification that includes the following:

[sampledbCS_1121]
TTC_Server=ttserver
TTC_SERVER_DSN=sampledb_1121
TTC_Timeout=30

ODBC.INI file example

The following example shows portions of a UNIX .odbc.ini file:

...
[ODBC Data Sources]
sampledb_1121=TimesTen 11.2.1 Driver
...
 
[sampledb_1121]
Driver=install_dir/lib/libtten.so
DataStore=install_dir/info/DemoDataStore/sampledb_1121
PermSize=40
TempSize=32
PLSQL=1
DatabaseCharacterSet=US7ASCII
...
 
########################################################################
# This following sample definitions should be in the .odbc.ini file
# that is used for the TimesTen 11.2.1 Client.
# The Server Name is set in the TTC_SERVER attribute.
# The Server DSN is set in the TTC_SERVER_DSN attribute.
#########################################################################
 
[ODBC Data Sources]
sampledbCS_1121=TimesTen 11.2.1 Client Driver
...
 
[sampledbCS_1121]
TTC_SERVER=localhost
TTC_SERVER_DSN=sampledb_1121
...

Changes to RAM policy after a fatal error

If a fatal error invalidates the database and the automatic database recovery performed by TimesTen is unsuccessful, the following occurs by default:

• TimesTen changes the always and manual RAM policies to InUse to prevent reoccuring errors. For both the always and manual RAM policies, TimesTen automatically reloads the database after each failure, even if the same failure occurs multiple times. However, for the InUse RAM policy, TimesTen will not automatically reload the database until a process tries to connect.

• If a fatal error causes the database to be invalidated, user processes connected to this database may not know that the database has been invalidated. In this case, the invalidated database will exist in memory until all user processes close their connections. Thus, the invalidated database could co-exist in memory with a newly reloaded database.

You can modify the default database recovery behavior by setting the -enablePolicyInactive option in the ttendaemon.options file before you start the TimesTen daemon. Once set, the following is the behavior when automatic recovery fails:

• The RAM policies of manual and always remain unchanged.

• The replication and cache agents are not restarted.

• After several failed attempts to reload the database, TimesTen sets the policyInactive mode, which prevents any more attempts at loading the database.

Any one of the following clears the policyInactive mode, so that normal behavior can resume:

• The TimesTen daemon restarts.

• A process connects successfully.

• The administrator executes a ttAdmin command for the database that changes the RAM policy, performs a RAM load, or starts either the cache or replication agents.

You can see if policyInactive mode is active when one of the following messages is displayed in the ttStatus output:

• "Automatic reloads disabled."

• "Data store should be manually loaded, but inactive due to failures." This is shown when the RAM policy is manual.

• "Data store should be loaded, but inactive due to failures." This is shown if the RAM policy is always.

Preventing an automatic reload of the database after failure

After a fatal error that causes the database to be invalidated, TimesTen attempts to reload and recover the database, as long as it is consistent with the settings for the RAM policy, cache agent policy, and replication agent policy. However, user processes could still be connected to the invalidated database if they do not know that the original database has been invalidated. In this case, the invalidated database will exist in memory until all user processes close their connections. Thus, the invalidated database could co-exist in memory with the newly reloaded database. This can be an issue if the database is large.

You can prevent the database from being automatically reloaded after an invalidation using the ttAdmin -noautoreload command. You can reset to the default automatic database reload behavior with the ttAdmin -autoreload command. See "ttAdmin" in the Oracle TimesTen In-Memory Database Reference for more details.

Any one of the following initiates a reload and recovery of the database so that normal behavior can resume:

• The TimesTen daemon restarts.

• A process connects successfully.

• The administrator executes a ttAdmin command for the database that changes the RAM policy, performs a RAM load, or starts either the cache or replication agents.

If you set the behavior to prevent automatic reloads of the database, you may receive the following error when connecting to a database that was not reloaded.

Error 707, "Attempt to connect to a data store that has been manually unloaded from RAM"

Estimating and modifying the data partition sizes for the database

Procedures, tables, or rows cannot be created in the database if the permanent or temporary data partition is full. In order to have the correct size for your database, set the appropriate size in the PermSize and TempSize connection attributes.

• PermSize connection attribute: The permanent data partition can be increased in size, but it cannot be decreased.

• TempSize connection attribute: The temporary data partition can be either increased or decreased in size for databases that do not participate in replication.

To make size estimates, use the ttSize utility or run the application until you can make a reasonable estimate.

You must make sure that you have a shared memory segment that is large enough to hold the database. In general, the minimum size of this shared memory segment should be:

PermSize + TempSize + LogBufMB + 20MB overhead

When you are calculating the amount of PermSize to allocate, take into account that PL/SQL procedures, functions and packages occupy space in the permanent data partition. The amount of permanent data partition required by a stored PL/SQL unit depends on the size and complexity of the unit. Small procedures can take less than 3 KBs, while larger ones can take considerably more. On average, reasonably complex units could be expected to use about 20 KBs of permanent data partition space.

For more details, see "Installation prerequisites" in Oracle TimesTen In-Memory Database Installation Guide and the descriptions of the TempSize and PermSize attributes in Oracle TimesTen In-Memory Database Reference.

Unloading the database from memory

Before you can change the size of either partition, you must first unload a database from memory, close all active connections to the database and set the RAM policy of the database to manual or inUse.

• To unload the database from memory, use the ttStatus utility to find processes connected to the database and stop them. Once you have made the changes for database size, reload it into memory.

  However, if the database is configured for replication, stop the cache and replication agents, if they are running. Reconfigure the database sizes for all replicas of the database. Once you have made the change in database size, read it into memory and restart the cache and replication agents.

• To set the RAM policy to manual or inUse, see "Specifying a RAM policy" for information.

Monitoring PermSize and TempSize attributes

The TimesTen table SYS.MONITOR contains several columns that can be used to monitor usage of PermSize and TempSize. These columns include PERM_ALLOCATED_SIZE, TEMP_ALLOCATED_SIZE, PERM_IN_USE_SIZE, PERM_IN_USE_HIGH_WATER, TEMP_IN_USE_SIZE, and TEMP_IN_USE_HIGH_WATER. Each of these columns show in KB units the currently allocated size of the database and the in-use size of the database. The system updates this information each time a connection is made or released and each time a transaction is committed or rolled back.

You can monitor block-level fragmentation in the database by using the ttBlockInfo built-in procedure. For more details, see "ttBlockInfo" in the Oracle TimesTen In-Memory Database Reference.

Receiving out-of-memory warnings

TimesTen provides two general connection attributes that determine when a low memory warning should be issued: PermWarnThreshold and TempWarnThreshold. Both attributes take a percentage value.

To receive out-of memory warnings, applications must call the built-in procedure ttWarnOnLowMemory.

These attributes also set the threshold for SNMP warning. See "Diagnostics through SNMP Traps" in the Oracle TimesTen In-Memory Database Error Messages and SNMP Traps.

Copying, migrating and restoring a database

The TimesTen utilities for copying, restoring and migrating a database enable you to perform the following:

• Migrate a database between releases of TimesTen. Use the ttMigrate utility. This utility saves tables and indexes from a TimesTen database into a binary file. The tables and indexes can then be restored into another TimesTen database. This allows you to migrate data between TimesTen releases.

• Migrate a database between different hardware platforms. Use the ttBulkCp utility to save and restore the data. The ttBulkCp utility copies data from TimesTen tables into ASCII files and back again, but only for those objects owned by the user executing the utility, and those objects for which the owner has SELECT privileges.

  The ttBulkCp utility enables you to copy a single table between databases, including between databases from different releases of TimesTen or between databases on different hardware platforms.

  The ttSchema utility saves the table definitions. Use ttIsql to re-create the tables from the saved table definitions.

• Take a snapshot of a database and then restore the database in the exact same state. Use the ttBackup and ttRestore utilities or the ttBackup and ttRestore C functions.

Backing up and restoring a database

The TimesTen backup and restore facility allows you to create a backup of any TimesTen database to restore it at a later time. The primary use for the backup and restore facility is to allow the restoration of a recent state of a database that has been lost.

Every database backup contains the information needed to restore the database as it existed at a the backup point, which is the time the backup began. Restoration of a database from a given backup restores the modifications of all transactions that committed before the backup point.

A backup operation is atomic: If it completes successfully, it will produce a backup that can be used to restore a database to the state of its backup point. If it fails for any reason, it leaves the files of any existing backup intact and its backup point unchanged.

TimesTen writes a database backup to a location specified by a backup path, which consists of a directory name and an optional basename. You must specify the backup directory and basename when the backup is created. The basename defaults to the basename of the database itself if you do not specify a basename.