1 Connection Attributes

Data Source Name

The data source name (DSN) uniquely identifies the attributes to a connection. It serves two purposes:

• As a unique identifier to the ODBC driver manager (if one is present), allowing it to associate a Data Store Name with a specific ODBC driver.

• As one of potentially many name aliases to a single physical database where the name alias has unique attributes associated with it.

The database attributes can apply to either the data source name (connection to a database) or the Data Store Path Name (database).

On Windows, the data source name and all configuration information associated with the data source (including the database path name) are stored in the system registry. The ODBC driver manager and TimesTen use this information.

DataStore

The database path name uniquely identifies the physical database. It is the full path name of the database and the file name prefix, for example: C:\data\AdminData. This name is not a file name. The actual database file names have suffixes, such as .ds0 and .log0, for example C:\data\AdminData.ds0 and C:\data\AdminData.log0.

DatabaseCharacterSet

The database character set determines the character set in which data is stored.

Generally, your database character set should be chosen based on the data requirements. For example: Do you have data in Unicode or is your data in Japanese on UNIX (EUC) or Windows (SJIS)?

You should choose a connection character set that matches your terminal settings or data source. See "ConnectionCharacterSet".

When the database and connection character sets differ, TimesTen performs the data conversion internally based on the connection character set. If the connection and database character sets are the same, TimesTen does not need to convert or interpret the data set. Best performance occurs when connection and database character sets match, since no conversion is required.

To use this attribute you must specify a supported character set. For a list of supported character set names, see "Supported character sets" below.

There are several things to consider when choosing a character set for your database. For a discussion about these considerations, see "Choosing a database character set" in Oracle TimesTen In-Memory Database Operations Guide.

Description

Optionally, set this attribute to help you identify the Data Source Name (DSN) and its attributes.

Driver

The Driver attribute specifies the name of the TimesTen ODBC Driver.

For example, on Windows systems the value can be TimesTen Data Manager 11.2.2 or TimesTen Client 11.2.2.On UNIX systems, the value of the Driver attribute is the path name of the TimesTen ODBC Driver shared library file. The file resides in the install_dir/lib directory.

LogDir

The LogDir attribute specifies the directory where database logs reside. Specifying this attribute enables you to place the transaction log files on a different I/O path from the database checkpoint files. This may improve throughput.

Preallocate

The Preallocate attribute determines whether TimesTen preallocates file system space for the database when the database is created. Setting this attribute ensures that there is sufficient space for the database when the database is saved to the file system.

Using Preallocate=1 in combination with ttRestore or ttRepAdmin -duplicate and a value of PermSize that does not match the value of PermSize of the original database may result in two checkpoint files with different sizes. This has not been shown to have negative effects. However, the issue can be avoided completely either by using the same PermSize as the original database or by setting Preallocate=0.

When a duplicate operation is carried out, the duplicated store has behavior consistent with a Preallocate setting of 0, even if it is set to 1 on the original or duplicated database. The behavior is indicated by the size of the checkpoint files, which is the sum of the size of the data and size of the database header.

The checkpoint files are subsequently allowed to grow to the same size as checkpoint files on the master database (PermSize + database header), but the space is not preallocated. The checkpoint files increase in size as data is added.

The reason for this behavior is that PreAllocate is set at database creation time. It is not a first connection attribute. The duplicate operation is not a database creation operation, so the preallocate attribute is not honored.

RangeIndexType

The RangeIndexType attribute specifies whether user-created range indexes use T-tree or B-tree indexes.

For more information on indexes, see "Overview of index types" in the Oracle TimesTen In-Memory Database Operations Guide.

ReplicationApplyOrdering

Enables parallel replication when used with the ReplicationParallelism attribute. With parallel replication, multiple transmitters on the master send to multiple receivers on the subscriber.

• Automatic parallel replication: Parallel replication over multiple threads that automatically enforces transactional dependencies and all changes applied in commit order. This is the default.

• Automatic parallel replication with disabled commit dependencies: Parallel replication over multiple threads that automatically enforces transactional dependencies, but does not enforce transactions committed in the same order on the subscriber database as on the active database. You can also increase replication throughput by applying transactions to specific tracks.

• User-defined parallel replication: For applications that use classic replication schemes, have very predictable transactional dependencies, and do not require that the commit order on the receiver is the same as that on the originating database. You can increase replication throughput by specifying the number of transaction tracks and apply specific transactions to each track. All tracks are read, transmitted and applied in parallel.

For more details on configuring parallel replication, see "Configuring parallel replication" in the Oracle TimesTen In-Memory Database Replication Guide.

This attribute also sets parallel propagation for AWT cache groups. By default, this attribute enables parallel propagation of updates to the Oracle database. To learn more about parallel AWT caching, see "Configuring parallel propagation to Oracle Database tables" in the Oracle TimesTen Application-Tier Database Cache User's Guide.

ReplicationParallelism

This attribute specifies the number of tracks, or the number of transmitter/receiver pairs, used for parallel replication.

The default value for this attribute is 1. This value indicates that single-threaded replication occurs. If the value is greater than 1, the LogBufParallelism first connection attribute must be an integral multiple of ReplicationParallelism.

To configure parallel replication, set this attribute to a value from 2 to 32, indicating the number of transmitter/receiver pairs.

If the CacheAWTParallelism attribute is set to 1 or not set, the maximum allowable value for ReplicationParallelism is 16.

To learn more about parallel replication, see "Configuring parallel replication" in the Oracle TimesTen In-Memory Database Replication Guide.

Temporary

Set this attribute to create a temporary database. Temporary databases are not saved to the file system. They may, however, be shared and therefore require a data store path name. A temporary database is deleted when the last connection is closed. See "Database persistence" in Oracle TimesTen In-Memory Database Operations Guide for more information. You cannot assign the Temporary data store attribute to an existing permanent database.

TypeMode

Specifies whether the names and semantics of the data types follow Oracle or TimesTen type rules. TimesTen supports both Oracle and TimesTen data types. The type mode determines what names are used to specify each data type. In some cases, a data type has both an alias name and a fixed type name. In such a situation, you can use either name. The TimesTen type mode is included for backward compatibility. When creating a DSN, use the default setting, Oracle type mode.

When caching data from an Oracle database in TimesTen, TypeMode must be set to 0.

See "Type specifications" in Oracle TimesTen In-Memory Database SQL Reference for a list of data types and their fixed and alias names.

AutoCreate

If you connect to a database that has the AutoCreate attribute set and the database does not exist yet, the database is created automatically if you supplied a valid existing path. With AutoCreate set, TimesTen creates the database, but not the path to the database. If you attempt to connect to a database that does not exist and the AutoCreate attribute is not set, the connection fails.

Also see "Overwrite".

CkptFrequency

Controls the frequency in seconds that TimesTen performs a background checkpoint. The counter used for the checkpoint condition is reset at the beginning of each checkpoint.

If both CkptFrequency and CkptLogVolume attributes have a value greater than 0, a checkpoint is performed when either of the two conditions becomes true. The values set by the ttCkptConfig built-in procedure replace the values set by these attributes.

In the case that your application attempts to perform a checkpoint operation while a background checkpoint is in process, TimesTen waits until the background checkpoint finishes and then executes the application's checkpoint. To turn off background checkpointing, set CkptFrequency=0 and CkptLogVolume=0.

The value of this attribute is "sticky" as it persists across database loads and unloads unless it is explicitly changed. The default value is only used during database creation. Subsequent first connections default to using the existing value stored in the database.

Regardless of the value of this attribute, if a checkpoint fails, TimesTen attempts a checkpoint only once every 10 minutes. If a checkpoint failure occurs due to a lack of file system space, we recommend that you attempt a manual checkpoint as soon as space is available. Once any successful checkpoint occurs, background checkpointing reverts to the configured schedule.

CkptLogVolume

Controls the amount of data in megabytes that collects in the log between background checkpoints. The counter used for the checkpoint condition is reset at the beginning of each checkpoint.

If both CkptFrequency and CkptLogVolume attributes have a value greater than 0, a checkpoint is performed when either of the two conditions becomes true. The values set by the ttCkptConfig built-in procedure replace the values set by these attributes.

In the case that your application attempts to perform a checkpoint operation while a background checkpoint is in process, TimesTen waits until the background checkpoint finishes and then executes the application's checkpoint. To turn off background checkpointing, set CkptFrequency=0 and CkptLogVolume=0.

The value of this attribute is "sticky" as it persists across database loads and unloads unless it is explicitly changed. The default value is only used during database creation. Subsequent first connections default to using the existing value stored in the database.

CkptRate

Controls the maximum rate at which data should be written to disk during a checkpoint operation. This may be useful when the writing of checkpoints to disk interferes with other applications.

All background checkpoints and by checkpoints initiated by the ttCkpt and ttCkptBlocking built-in procedures use the rate specified by this connection attribute. Foreground checkpoints (checkpoints taken during first connect and last disconnect) do not use this rate. The rate is specified in MB per second.

A value of 0 disables rate limitation. This is the default. The value can also be specified using the ttCkptConfig built-in procedure. The value set by the ttCkptConfig built-in procedure replaces the value set by this attribute.

The value of this attribute is "sticky" as it persists across database loads and unloads unless it is explicitly changed. The default value is only used during database creation. Subsequent first connections default to using the existing value stored in the database. If left unspecified (or empty in the Windows ODBC Data Source Administrator), TimesTen uses the stored setting. To turn the attribute off, you must explicitly specify a value of 0. For existing databases that are migrated to this release, the value is initialized to 0. To use the current or default value, the attribute value should be left unspecified.

For more details about the benefits of and issues when using CkptRate, see "Setting the checkpoint rate" in Oracle TimesTen In-Memory Database Operations Guide.

CkptReadThreads

Determines the number of threads used to read the checkpoint file when loading the database into memory, such as in first connection or recovery operations.

When the CkptReadThreads attribute is set to 1, TimesTen reads checkpoint files serially. When the CkptReadThreads attribute is set to a value greater than 1, TimesTen uses the specified number of threads to read checkpoint files concurrently. When the CkptReadThreads attribute is set to 0 or unspecified, the previously specified value is used.

Connections

Indicates the upper bound on the number of user-specified concurrent connections to the database. TimesTen allocates one semaphore for each expected connection. If the number of connections exceeds the value of this attribute, TimesTen returns an error.

The number of current connections to a database can be determined by viewing the output from the ttStatus utility.

A Connections value of 0 or no value indicates that you should use the default number of semaphores. The maximum number of allowed connections is 2047. TimesTen reserves 47 connections for internal use, leaving a maximum of 2000 connections available to applications. As a guideline, set this value to the maximum number of expected application connections plus ten percent.

If you receive an error indicating that the number of connections exceeds the value of this attribute, increase the value until you no longer receive this error.

When you enable PL/SQL (PLSQL=1), there is both a fixed and per connection overhead allocated from the PL/SQL segment, even if you do not use PL/SQL. For details, see "PLSQL_MEMORY_SIZE".

ForceConnect

When return receipt replication is used with the NONDURABLE TRANSMIT option, a failed master database is allowed to recover only by restoring its state from a subscriber database using the -duplicate option of the ttRepAdmin utility. In other words, the failed database cannot just come up and have replication bring it up to date because it may lose some transactions that were transmitted to the subscriber but not durably committed locally. The ForceConnect connection attribute overrides this restriction.

The ttConfiguration built-in procedure does not return the value of the ForceConnect attribute.

LogAutoTruncate

Determines whether the first connection to the database should proceed if TimesTen recovery encounters a defective log record.

LogBufMB

The LogBufMB attribute specifies the size of the internal transaction log buffer in megabytes. The default log buffer size is 64 megabytes.

If you change the value of LogBufMB, you also may need to change the value of LogBufParallelism to satisfy the constraint that LogBufMB/LogBufParallelism >=8.

If you increase the value of LogBufMB, ensure the value of LogFileSize is greater than or equal to the value of LogBufMB (LogFileSize >= LogBufMB).

LogBufParallelism

The LogBufParallelism attribute specifies the number of transaction log buffer strands to which TimesTen writes log files before the log is written to disk, allowing for improved log performance. Each buffer has its own insertion latch. Records are inserted in any of the strands. The log flusher gathers records from all strands and writes them to the log files.

The maximum number of strands is 64. The default is 4.

If you change the value of LogBufParallelism, you also may need to change the value of LogBufMB to satisfy the constraint that LogBufMB/LogBufParallelism >=8.

LogFileSize

The LogFileSize attribute specifies the maximum size of transaction log files in megabytes. The minimum value is 8 MB. The default value is 64 MB. If you specify a size smaller than 8 MB, TimesTen returns an error message. Before TimesTen release 11.2.1.4, the minimum size was 1 MB. If you created your database in a previous release of TimesTen and specified a log file size of less than 8 MB, you must increase the value assigned to this attribute to avoid an error.

Actual transaction log file sizes may be slightly smaller or larger than LogFileSize because log records cannot span transaction log files.

If you specify a value of zero, TimesTen uses the default transaction log file size if the database does not exist. If the database exists, TimesTen uses the current specified transaction log file size.

Set the value of LogFileSize to be larger than or equal to the value of LogBufMB (LogFileSize >= LogBufMB).

LogFlushMethod

Controls the method used by TimesTen to write and sync log data to transaction log files. The overall throughput of a system can be significantly affected by the value of this attribute, especially if the application chooses to commit most transactions durably.

As a general rule, use the value 2 if most of your transactions commit durably and use the value 1 otherwise.

For best results, however, experiment with both values using a typical workload for your application and platform. Although application performance may be affected by this attribute, transaction durability is not affected. Changing the value of this attribute does not affect transaction durability in any way.

LogPurge

If the LogPurge attribute is set, TimesTen automatically removes transaction log files when they have been written to both checkpoint files and there are no transactions that still need the transaction log files' contents. The first time checkpoint is called, TimesTen writes the contents of the transaction log files to one of the checkpoint files. When checkpoint is called the second time, TimesTen writes the contents of the transaction log files to the other checkpoint file.

TimesTen purges the transaction log files if all these conditions are met:

• The contents of the transaction log files have been written to both checkpoint files.

• The transaction log files are not pending incremental backup.

• If replication is being used, the transaction log files have been replicated to all subscribers.

• If XLA is being used, all XLA bookmarks have advanced beyond the transaction log files.

• The transaction log files are not being used by any distributed transactions using the XA interface.

If this attribute is set to 0 or unchecked, unneeded transaction log files are appended with the.arch suffix. Applications can then delete the files.

MemoryLock

On Solaris, Linux and Windows 64-bit systems, TimesTen enables applications that connect to a shared database to specify whether the real memory should be locked while the database is being loaded into memory or while the store is in memory. If the physical memory used for the database is locked, the operating system's virtual memory subsystem cannot borrow that memory for other uses. No part of the database is ever paged out but this could lead to memory shortages in a system that is under configured with RAM. While memory locking can improve database load performance, it may impede other applications on the same computer.

On AIX the MemoryLock attribute is not implemented. The shared memory segment is locked when you use large pages, on AIX. You can lock the shared segment by using large pages. The Oracle TimesTen In-Memory Database Installation Guide contains more details about large pages.

The PL/SQL shared memory segment is not subject to MemoryLock.

On Linux systems, set the groupname in the MemLock setting to be the same as the instance administrator in the /etc/security/limits.conf file. Set the value of MemLock to be at least as large as the TimesTen database shared memory segment.

On Solaris systems, the instance administrator must have the proc_lock_memory privilege to set MemoryLock to 1 or 2. No special privileges are required to set MemoryLock to 3 or 4. Setting MemoryLock to 3 or 4 enables use of Solaris "intimate shared memory (ISM)".

To view privileges, use:

% ppriv $$ 

To add the privilege for user ID timesten, a root user uses:

# usermod -K defaultpriv=basic,proc_lock_memory timesten 

After adding the privilege, the timesten user must log in to a new shell, unload all TimesTen databases from memory and restart the TimesTen daemons.

To restart the TimesTen daemons, in the new login shell, use:

% ttDaemonadmin -restart

Overwrite

If the Overwrite attribute is set and there is an existing database with the same database path name as the new database, TimesTen destroys the existing database and creates a new empty database if the existing database is not in use. If the Overwrite attribute is set and there is not a database with the specified database path name, TimesTen only creates a new database if the AutoCreate attribute is also set (see "AutoCreate"). TimesTen ignores the Overwrite attribute if AutoCreate is set to 0. Applications should use caution when specifying the Overwrite =1 attribute.

PermSize

Indicates the size in MB of the permanent memory region for the database. You may increase PermSize at first connect but not decrease it. TimesTen returns a warning if you attempt to decrease the permanent memory region size. If the database does not exist, a PermSize value of 0 or no value indicates to use the default size. Default size is 32 MB. For an existing database, a value of 0 or no value indicates that the existing size should not be changed.

Once you have created a database, you can make the permanent partition larger, but not smaller. See "Specifying the size of a database" in Oracle TimesTen In-Memory Database Operations Guide.

Also see information about the TempSize connection attribute.

The ttMigrate and ttDestroy utilities can also be used to change the Permanent Data Size, when appropriate.

ReceiverThreads

This attribute controls the number of threads used to apply changes on the active master database to the standby master database in an active standby pair replication scheme. The default is 1. You can also set this attribute on one or more read-only subscribers in an active standby pair replication scheme to increase replication throughput from the standby master database to the subscribers.

By default, a receiver thread in the replication agent applies the changes to the standby master database. When this attribute is set to 2, an additional thread applies the changes. Databases must be hosted on systems that have two cores (or hardware threads) or more to take advantage of setting this attribute to 2.

If you set this attribute to 2 on the standby master database, you should also set it to 2 on the active master database to maintain increased throughput if there is a failover.

RecoveryThreads

The RecoveryThreads attribute determines the number of threads used to rebuild indexes during recovery.

If RecoveryThreads=1, during recovery, indexes that must be rebuilt are done serially. If you have enough processors available to work on index rebuilds on your computer, setting this attribute to a number greater than 1 can improve recovery performance. The performance improvement occurs only if different processors can work on different indexes. There is no parallelism in index rebuild within the same index.

The value of RecoveryThreads can be any value up to the number of CPUs available on your system.

The default is 1 when the database is created. Upon subsequent connections, if the database must be recovered and RecoveryThreads is unspecified or has a value of 0, then TimesTen uses the previous setting for this attribute.

TempSize

TempSize indicates the total amount of memory in MB allocated to the temporary region.

TempSize has no predefined value. If left unspecified, its value is determined from PermSize as follows:

• If PermSize is less than 64 MB, TempSize = 32 MB + ceiling(PermSize / 4 MB).

• Otherwise, TempSize = 40 MB + ceiling(PermSize / 8 MB).

TimesTen rounds the value up to the nearest MB.

If specified, TimesTen always honors the TempSize value. Since the temporary data partition is recreated each time a database is loaded, the TempSize attribute may be increased or decreased each time a database is loaded. For an existing database, a value of 0 or no value indicates that the existing size should not be changed. The minimum TempSize is 32 MB.

CommitBufferSizeMax

CommitBufferSizeMax indicates the total amount of memory in MB allocated to the transaction commit buffer. Set this attribute to handle the size of reclaim records.

You can use the ALTER SESSION SQL statement, described in Oracle TimesTen In-Memory Database SQL Reference, to assign or change the maximum size of the commit buffer within a session. The new value takes effect when a new transaction starts.

ALTER SESSION SET COMMIT_BUFFER_SIZE_MAX = n;

You can see the configured maximum for the commit buffer by calling the ttConfiguration built-in procedure.

For more information on reclaim operations, including details about setting the commit buffer size, see "Transaction reclaim operations" in the Oracle TimesTen In-Memory Database Operations Guide. Also see information about the ttCommitBufferStats and the ttCommitBufferStatsReset built-in procedures.

ConnectionName

This attribute is also available as a Client connection attribute.

This attribute enables you to attach a symbolic name to any database connection. Connection names are unique within a process.

TimesTen uses the symbolic name to help identify the connection in various administrative utilities, such as ttIsql, ttXactAdmin and ttStatus. This can be particularly useful with processes that make multiple connections to the database, as is typical with multithreaded applications or in the identification of remote clients.

The value of this attribute is intended to be dynamically defined at connection time using the connection string. The default value is the connecting executable file name. It can also be defined statically in the DSN definition. Values used for ConnectionName should follow SQL identifier syntax rules.

DDLCommitBehavior

This attribute controls transactional commit behavior in relation to data definition language (DDL) statements.

You can set it to the traditional TimesTen behavior or to the Oracle database behavior.

• Traditionally, in TimesTen databases, DDL statements are executed as part of the current transaction and are committed or rolled back along with the rest of the transaction.

• The Oracle database issues an implicit COMMIT before and after any DDL statement.

DDL statements include:

• CREATE, ALTER or DROP of any database object (including tables, views, user procedures, and indexes)

• TRUNCATE

• GRANT and REVOKE

AUTOCOMMIT OFF;
CREATE TABLE t1 (c1 Varchar2(10));
COMMIT;

INSERT INTO t1 VALUES('some data');
1 row inserted.

CREATE TABLE t2 (c1 INTEGER);

ROLLBACK;

SELECT * FROM t1;
0 rows found.

SELECT * FROM t2;
2206: Table ttuser.t2 not found
The command failed.

INSERT INTO t1 VALUES('more data');
1 row inserted.

CREATE TABLE t1 (c1 VARCHAR2(10));
 2207: Table t1 already exists
The command failed.

ROLLBACK;

SELECT * FROM t1;
0 rows found.

-- implicit commit here

Command> CREATE TABLE t1 (c1 varchar2(10));
Table created.

-- implicit commit here

Command> COMMIT;
Commit complete.

Command> INSERT INTO t1 VALUES('some data');
1 row created.

-- implicit commit here
Command> CREATE TABLE t2 (c1 INTEGER);
Table created.

-- implicit commit here

SQL> ROLLBACK;
Rollback complete.

Command> SELECT * FROM t1;
C1
----------
some data

Command> SELECT * FROM t2;
no rows selected

Command> INSERT INTO t1 VALUES('more data');
1 row created.
-- implicit commit here

Command> CREATE TABLE t1 (c1 VARCHAR2(10));
CREATE TABLE t1 (c1 VARCHAR2(10))
             *
ERROR at line 1:
ORA-00955: name is already used by an existing object

-- implicit rollback

Command> ROLLBACK;
Rollback complete.

Command> SELECT * FROM t1;
C1
----------
some data
more data

DDLReplicationAction

Determines whether a table or a sequence is included in an active standby pair replication scheme when created. The table can be included if the DDLReplicationLevel connection attribute is set to 2 or 3. The sequence can be included if the DDLReplicationLevel connection attribute is set to 3.

Replication of DDL operations is enabled (with restrictions) by the set value of the DDLReplicationLevel connection attribute. For more details, see "DDLReplicationLevel".

The value may be modified by an ALTER SESSION SQL statement, described in Oracle TimesTen In-Memory Database SQL Reference. For example:

ALTER SESSION SET DDL_REPLICATION_ACTION='EXCLUDE';

Values set by ALTER SESSION override the value set by this attribute.

For examples of altering an active standby pair, see "Altering an Active Standby Pair" in the Oracle TimesTen In-Memory Database Replication Guide.

When DDLCommitBehavior=0 (the default), DDL operations are automatically committed. When RETURN TWOSAFE has been specified, errors and timeouts may occur as described in "RETURN TWOSAFE" in the Oracle TimesTen In-Memory Database Replication Guide. If a RETURN TWOSAFE timeout occurs, the DDL transaction is committed locally regardless of the LOCAL COMMIT ACTION that has been specified.

To learn more about replicating DDL, see "Changing user names or passwords used by replication" in the Oracle TimesTen In-Memory Database Replication Guide.

DDLReplicationLevel

Enables replication of a subset of data definition language (DDL) statements (with restrictions) in an active standby replication scheme.

When the value of the DDLReplicationLevel connection attribute is set to 1, CREATE or DROP statements for tables, indexes, or synonyms are not replicated to the standby database. However, you can add or drop columns with the ALTER TABLE ADD or DROP COLUMN to or from a replicated table, and those actions are replicated to the standby database.

When the value of the DDLReplicationLevel connection attribute is set to 2 (the default), the following DDL statements (described in Oracle TimesTen In-Memory Database SQL Reference) are replicated to the standby and any subscribers:

• CREATE or DROP INDEX

• CREATE or DROP SYNONYM

• CREATE or DROP TABLE (including global temporary tables but not CREATE TABLE AS SELECT)

When the value of the DDLReplicationLevel connection attribute is set to 3, the following DDL statements (described in Oracle TimesTen In-Memory Database SQL Reference) and those replicated when the value is set to 2 are replicated to the standby and any subscribers:

• CREATE or DROP VIEW

• CREATE or DROP SEQUENCE

• Replication of the results to the standby master when setting the cache administration user name and password with the UidPwdSet built-in procedure. You do not need to stop and restart the cache agent or replication agent to execute the UidPwdSet built-in procedure. For more information, see "Changing cache user names or passwords" in the Oracle TimesTen Application-Tier Database Cache User's Guide or "ttCacheUidPwdSet".

The value of this attribute may be modified by an ALTER SESSION statement, described in Oracle TimesTen In-Memory Database SQL Reference. For example:

ALTER SESSION SET DDL_REPLICATION_LEVEL=3;

Values set by ALTER SESSION override the value set by this attribute.

For examples of altering an active standby pair, see "Altering an Active Standby Pair" in the Oracle TimesTen In-Memory Database Replication Guide.

To learn more about replicating DDL, see "Changing user names or passwords used by replication" in the Oracle TimesTen In-Memory Database Replication Guide.

Diagnostics

Enables an application to configure the level of diagnostics information generated by TimesTen for the connection. TimesTen diagnostics messages are warnings whose numbers lie within the range 20000 through 29999. Diagnostics connection attribute values are integers.

DuplicateBindMode

This attribute determines whether applications use traditional TimesTen parameter binding for duplicate occurrences of a parameter in a SQL statement or Oracle-style parameter binding.

Traditionally, in TimesTen, multiple instances of the same parameter name in a SQL statement are considered to be multiple occurrences of the same parameter. When assigning parameter numbers to parameters, TimesTen assigns parameter numbers only to the first occurrence of each parameter name. The second and subsequent occurrences of a given name do not get their own parameter numbers. In this case, A TimesTen application binds a value for every unique parameter in a SQL statement. It cannot bind different values for different occurrences of the same parameter name nor can it leave any parameters or parameter occurrences unbound.In Oracle Database, multiple instances of the same parameter name in a SQL statement are considered to be different parameters. When assigning parameter numbers, Oracle Database assigns a number to each parameter occurrence without regard to name duplication. An Oracle Database application, at a minimum, binds a value for the first occurrence of each parameter name. For the subsequent occurrences of a given parameter, the application can either leave the parameter occurrence unbound or it can bind a different value for the occurrence.

For more details on parameter binding, see Oracle TimesTen In-Memory Database SQL Reference.

DurableCommits

By default, DurableCommits is set to 0. With this setting, TimesTen writes a log record to the file system when a transaction is committed, but the log record is not immediately written to disk. This reduces transaction execution time at the risk of losing some committed transactions if a failure occurs. When DurableCommits is set to 1, TimesTen writes a log record to disk when the transaction is committed.

A connection can also call the ttDurableCommit built-in procedure to do durable commits explicitly on selected transactions. A call to ttDurableCommit flushes the log buffer to disk. The log buffer is shared among all connections and contains log records from transactions of all connections.

Log records are continually copied from the file system to disk. You can use LogFlushMethod to control when the file system is synchronized with the disk.

Isolation

By default, TimesTen uses read committed isolation. The Isolation attribute specifies the initial transaction isolation level for the connection. For a description of the isolation levels, see "Concurrency control through isolation and locking" in Oracle TimesTen In-Memory Database Operations Guide.

The value may be modified by an ALTER SESSION statement, described in Oracle TimesTen In-Memory Database SQL Reference. For example:

ALTER SESSION SET ISOLATION_LEVEL=serializable;

CREATE CACHE GROUP, ALTER CACHE GROUP and DROP CACHE GROUP statements are not supported in serializable isolation mode.

If the passthrough or the propagate TimesTen Cache feature is used, the TimesTen isolation level setting is inherited by the Oracle session. TimesTen serializable mode is mapped to Oracle's serializable mode. TimesTen read committed mode is mapped to Oracle's read committed mode. For more details on the passthrough attribute, see "PassThrough".

With PassThrough set to 3, you must use an ALTER SESSION statement to permanently modify the isolation level on the Oracle database connection. For example on a connection to the DSN repdb1_1122:

1. Call ttIsql and connect to the DSN with PassThrough level 3:

   % ttIsql;
   Command> connect "dsn=repdb1_1122;passthrough=3";
   Connection successful:. . .PassThrough=3; TypeMode=0;
   <default setting Autocommit=1>
   

2. Turn off AutoCommit:

   Command> autocommit=0;
   

3. Temporarily change the PassThrough level to 0:

   Command> passthrough=0;
   

4. Alter the isolation level to serializable:

   Command> prepare 1 ALTER SESSION SET ISOLATION_LEVEL=serializable;
   Command> commit;
   Command> exec=1;
   

LockLevel

By default, TimesTen enables row-level locking for maximum concurrency. With row-level locking, transactions usually obtain locks on the individual rows that they access, although a transaction may obtain a lock on an entire table if TimesTen determines that doing so would result in better performance. Row-level locking is the best choice for most applications, as it provides the finest granularity of concurrency control. To use row-level locking, applications must set the LockLevel connection attribute to 0 (the default value). To cache Oracle database tables, you must set row-level locking. To CREATE, DROP, or ALTER a user, you can only use row-level locking and thus, the lock level must be set to 0 before you can perform any of these operations.

To give every transaction in this connection exclusive access to the database, you can enable database-level locking by setting the LockLevel attribute to 1. Doing so may improve performance for some applications.

A connection can change the desired lock level at any time by calling the ttLockLevel built-in procedure. Connections can also wait for unavailable locks by calling the ttLockWait built-in procedure. Different connections can coexist with different levels of locking, but the presence of even one connection doing database-level locking leads to loss of concurrency. To display a list of all locks on a particular database you can use the ttXactAdmin utility.

When using PL/SQL in your applications, set LockLevel=0 and selectively change to database level locking for specific transactions that require that level of locking by using the ttLockLevel built-in procedure.

LockWait

Enables an application to configure the lock wait interval for the connection. The lock wait interval is the number of seconds to wait for a lock when there is contention on it. Sub-second LockWait values significant to tenths of a second can be specified using decimal format for the number of seconds. For example:

LockWait = 0.1

results in a lock wait of one tenth of a second.

LockWait may be set to any value between 0 and 1,000,000 inclusive to a precision of tenths of a second. The default is 10 seconds:

LockWait = 10.0

Actual lock wait response time is imprecise and may be exceeded by up to one tenth of a second, due to the scheduling of the agent that detects timeouts. This imprecision does not apply to zero second timeouts, which are always reported immediately.

The number of connections to a database can impact the time needed to resolve lock contentions. If you anticipate having many connections to the database, increase the lock wait interval.

Cache grid uses message wait time with lock wait time. When using cache grid, lock wait times are approximately half the value you have specified. If your applications require the full lock wait time, specify twice the desired seconds.

A connection can change the lock wait interval at any time by calling the ttLockWait built-in procedure.

To display a list of all locks on a particular database you can use the TimesTen utility ttXactAdmin.

MatchLogOpts

The first connection to a database determines whether the transaction log files are purged. Any subsequent connection must specify the same value for the LogPurge attribute or TimesTen generates an error. If a connection does not know the current state of the LogPurge attribute, MatchLogOpts can be set so that the logging attributes match.

PermWarnThreshold

Indicates the threshold percentage at which TimesTen issues out-of-memory warnings for the permanent partition of the database's memory. The database is considered no longer out of permanent memory if it falls 10% below this threshold. An application must call the built-in procedure ttWarnOnLowMemory to receive out-of-memory warnings. The threshold also applies to SNMP warnings. Also see "Diagnostics through SNMP Traps" in Oracle TimesTen In-Memory Database Error Messages and SNMP Traps.

PrivateCommands

When multiple connections execute the same command, they access common command structures controlled by a single command lock. To avoid sharing their commands and possibly placing contention on the lock, you can use PrivateCommands. This gives you better scaling at the cost of increased temporary space usage.

By default, the PrivateCommands is turned off and commands are shared.

PWDCrypt

The PWDCrypt contains an encrypted version of the corresponding PWD value. The value for PWD is stored in clear text, which does not allow special characters, in the .odbc.ini file on UNIX and in the Windows Registry on Windows. Any users who have access to the .odbc.ini file or Windows Registry can view the value for this attribute. The PWDCrypt attribute enables special characters, is case sensitive and contains the value of the encrypted password.

For security reasons, the PWDCrypt attribute should only be placed in User DSNs or user private ODBCINI files. The presence of the PWDCrypt in System DSNs enables any user to use the PWDCrypt value to connect to TimesTen, even though they have no knowledge of the cleartext password.

To generate the value for this attribute, run the ttUser utility.

QueryThreshold

Use this attribute to write a warning to the support log and throw an SNMP trap when the execution time of a SQL statement exceeds the specified value. For queries executed by the replication agent, see Oracle TimesTen In-Memory Database Replication Guide. You cannot set a query threshold for a SQL statement that is executed by the cache agent. The value of QueryThreshold applies to all connections. It applies to all SQL statements except those executed by the replication agent or the cache agent.

The value of this attribute can be any integer equal to or greater than 0. The default value is 0. A value of 0 indicates that no warning is issued. The unit is seconds.

ReplicationTrack

When managing track-based parallel replication, you can assign a connection to a replication track. All transactions issued by the connection are assigned to this track, unless the track is altered.

To start track-based parallel replication you must set a value for the ReplicationParallelism attribute, specifying the number of replication tracks to be applied in parallel. You must also set ReplicationApplyOrdering either to 1 or 2, depending on if you are using automatic or user-defined parallel replication.

The Track_ID column of the TTREP.REPPEERS system table (described in Oracle TimesTen In-Memory Database System Tables and Views Reference) shows the track associated with the connection.

You can use the ALTER SESSION SQL statement, described in Oracle TimesTen In-Memory Database SQL Reference, to assign or change the value of this attribute within a session. For example:

ALTER SESSION SET REPLICATION_TRACK=4;

SQLQueryTimeout

Use this attribute to specify the time limit in seconds within which the database should execute SQL statements.

The value of SQLQueryTimeout can be any integer equal to or greater than 0. The default value is 0. A value of 0 indicates that the query does not time out.

This attribute does not stop TimesTen Cache operations that are being processed on an Oracle database. This includes passthrough statements, flushing, manual loading, manual refreshing, synchronous writethrough, and propagating.

TempWarnThreshold

Indicates the threshold percentage at which TimesTen issues out-of-memory warnings for the temporary partition of the database's memory. The database is considered no longer out of temporary memory if it falls 10% below this threshold. An application must call the built-in procedure ttWarnOnLowMemory to receive out-of-memory warnings. The threshold also applies to SNMP warnings. See "ttWarnOnLowMemory". Also see "Diagnostics through SNMP Traps" in Oracle TimesTen In-Memory Database Error Messages and SNMP Traps

UID and PWD

A user ID and password must be provided by a user who is identified internally to TimesTen. Alternatively, an encrypted password can be supplied using the PWDCrypt attribute. Some TimesTen operations prompt for the UID and PWD of the user performing the operation.

For TimesTen client/server applications, specify UID and PWD either in the Client DSN configuration or in the connection string. The UID and PWD values specified in a connection string take precedence over the values specified in the Client DSN configuration.

When caching Oracle database tables, PWD specifies the TimesTen password while OraclePWD specifies the Oracle password.

% ttIsql -connStr "DSN=mydsn;UID=terry;PWD=secret";

WaitForConnect

When an application requests a connection to a TimesTen database and the connection is not possible (perhaps during concurrent loading/recovery of a database), TimesTen normally waits for completion of the conflicting connection. In some cases, it can take some time for an application to connect to a database. If the WaitForConnect attribute is off and the database is not immediately accessible, TimesTen returns immediately an error. For a description of the error, look for the error message number in "Warnings and Errors" in Oracle TimesTen In-Memory Database Error Messages and SNMP Traps.

ConnectionCharacterSet

ConnectionCharacterSet is also available as a Client connection attribute.

This attribute specifies the character encoding for the connection, which may be different from the database character set. This can be useful when you have multiple connections to a database and one or more of those connections requires a character set that differs from that specified in the database.

The connection character set determines the character set in which data is displayed or presented.

Generally, you should choose a connection character set that matches your terminal settings or data source. Your database character set should be chosen based on the data requirements. For example: Do you have data in Unicode or is your data in Japanese on UNIX (EUC) or Windows (SJIS)?

When the database and connection character sets differ, TimesTen performs data conversion internally based on the connection character set. If the connection and database character sets are the same, TimesTen does not need to convert or interpret the data set. Best performance occurs when connection and database character sets match, since no conversion is required.

Parameters and SQL query text sent to the connect should be in the connection character set. Results and error messages returned by the connection are returned in the connection character set.

Character set conversions are not supported for the TIMESTEN8 character set. A ConnectionCharacterSet value of TIMESTEN8 results in an error if the value assigned to the DatabaseCharacterSet is not TIMESTEN8.

This attribute accepts the same values used for the DatabaseCharacterSet. For a list of supported character set names, see "Supported character sets".

NLS_LENGTH_SEMANTICS

TimesTen uses the NLS_LENGTH_SEMANTICS attribute to set the default length semantics configuration. Length semantics determines how the length of a character string is determined. The length can be treated as a sequence of characters or a sequence of bytes.

NLS_NCHAR_CONV_EXCP

The NLS_NCHAR_CONV_EXCP attribute determines whether an error is reported when there is data loss during an implicit or explicit character type conversion between NCHAR/NVARCHAR2 data and CHAR/VARCHAR2 data. A replacement character is substituted for characters that cannot be converted.

Implicit and explicit conversions between CHAR and NCHAR are supported, unless the database uses the TIMESTEN8 character set.

NLS_SORT

The NLS_SORT attribute indicates which collating sequence to use for linguistic comparisons. It accepts the values listed in "Supported Linguistic Sorts." All these values can be modified to do case-insensitive sorts by appending _CI to the value. To perform accent-insensitive and case-insensitive sorts, append _AI to the value.

For materialized views and cache groups, TimesTen recommends that you explicitly specify the collating sequence using the NLSSORT SQL function rather than using this attribute in the connection string or DSN definition.

Operations involving character comparisons support linguistic case-sensitive collating sequences. Case-insensitive sorts may affect DISTINCT value interpretation.

NLS_SORT may affect many operations. The supported operations that are sensitive to collating sequence are:

• MIN, MAX

• BETWEEN

• =, <>, >, >=, <, <=

• DISTINCT

• CASE

• GROUP BY

• HAVING

• ORDER BY

• IN

• LIKE

Only BINARY sort is supported with the TIMESTEN8 character set.

NLS_SORT settings other than BINARY may have significant performance impact on character operations.

PLSQL

This attribute determines whether PL/SQL is configured for the database.

Specifying PLSQL=1 enables PL/SQL use in the database. Specifying PLSQL=0 disables PL/SQL use in the database.

In TimesTen installations where PL/SQL support was enabled at installation time, the default is PLSQL=1. Or PL/SQL may be enabled when the database is initially created, or at any first connect afterward. Once PL/SQL support is enabled in a database, you cannot disable it later.

Configuring PL/SQL support in a database results in the installation of several PL/SQL packages that are documented in Oracle TimesTen In-Memory Database PL/SQL Packages Reference.

Some things to be aware of when setting this attribute are:

• If an application connects to a database that has PL/SQL enabled, and the application or odbc.ini file specifies PLSQL=0, TimesTen returns a warning.

• If an application connects to a database that does not have PL/SQL enabled, and the application or odbc.ini file specifies PLSQL=1, what happens depends on whether this is a first connect or a subsequent one. At first connect, the database is configured to support PL/SQL. Otherwise, TimesTen returns an error.

• If PLSQL=0, all PL/SQL first and general connection attributes are ignored.

• If PLSQL=0, any attempt to change the value of a PL/SQL general connection attributes returns an error.

• If PLSQL=1, we recommend setting LockLevel=0 for the connection. If database level locking is enabled, some PL/SQL internal functions cannot be performed. You can use the ttLockLevel built-in procedure to selectively change to database-level locking only for those specific transactions that require it.

• If PL/SQL support is enabled, the DDLCommitBehavior must be the Oracle transactional commit behavior (value 0).

• When you enable PL/SQL (PLSQL=1), there is both a fixed and per connection overhead allocated from the PL/SQL segment, even if you do not use PL/SQL. For details, see "PLSQL_MEMORY_SIZE".

PLSQL_MEMORY_ADDRESS

Use of PL/SQL requires a shared memory segment. This shared memory contains recently-executed PL/SQL code, shared package state, and metadata associated with the operation of PL/SQL. This shared memory segment is separate from the one containing the TimesTen database.

This attribute determines the virtual address at which this shared memory segment is loaded into each process that uses the TimesTen "direct" drivers. This memory address must be identical in each process using TimesTen. You must specify the value as a hexadecimal address.

If PL/SQL use is enabled (PLSQL=1) and you have not specified a value for PLSQL_MEMORY_ADDRESS, TimesTen uses a platform-dependent default value.

The default values for each platform are designed to:

1. Maximize the amount of virtual space for your TimesTen database and for your applications.

2. Minimize the fragmentation of the virtual address space.

3. Avoid conflicts with other uses of virtual address space.

The platform specific default memory addresses are:

Some things to consider when setting this attribute are:

• If applications simultaneously connect to multiple TimesTen databases in direct mode, then each database must use a different value for PLSQL_MEMORY_ADDRESS.

• The value of this attribute is stored persistently by TimesTen. The persistent attribute value is specified in situations when the database is loaded automatically by TimesTen. For example, the database is automatically loaded if RamPolicy for the database is set to 1.

• If the PL/SQL shared memory cannot be mapped at the appropriate address, TimesTen returns an error and the connection to the database fails.

• The memory segment size is determined by the value of PLSQL_MEMORY_SIZE.

PLSQL_MEMORY_SIZE

Use of PL/SQL requires a shared memory segment. This attribute determines the size in megabytes of the shared memory segment used by PL/SQL. All connections share this memory segment.

This shared memory contains recently-executed PL/SQL code, the shared package state, and metadata associated with the operation of PL/SQL. This shared memory segment is separate from the one containing the TimesTen database.

Some things to consider when setting this attribute are:

• The value of this attribute is stored persistently by TimesTen. The persistent attribute value is specified in situations when the database is loaded automatically by TimesTen. For example, the database is automatically loaded if RamPolicy for the database is set to 1.

• The default memory size is 32 MB on UNIX systems and 32 MB on Windows 32-bit systems. The minimum size is 2 MB, if PLSQL=1. For most PL/SQL users, the default memory size should be an adequate amount of memory. For databases that make extensive use of PL/SQL, specify a larger memory size. If the memory space is exhausted, ORA-4031 errors may occur during PL/SQL execution.

• The address of the memory segment is determined by the value of PLSQL_MEMORY_ADDRESS.

• When you enable PL/SQL (PLSQL=1), there is both a fixed and per connection overhead allocated from the PL/SQL segment, even if you do not use PL/SQL. The minimum fixed memory allocated is approximately 1500 KB. Additionally, approximately 40 KB of memory is allocated per connection. Thus, you can compute an estimated minimum memory setting needed when enabling PL/SQL for PLSQL_MEMORY_SIZE as 1500 KB plus (number_of_connections * 40). If the application uses PL/SQL, we recommend that you allocate twice the estimated minimum required memory for this segment. If the application does not use PL/SQL, you can allocate less than twice the estimated minimum required memory.

PLSCOPE_SETTINGS

PLSCOPE_SETTINGS controls whether the PL/SQL compiler generates cross-reference information. Either all or no cross-references are generated.

Some things to consider when setting this attribute are:

• The PLSCOPE_SETTINGS connection attribute determines the initial value of this attribute within a session. The value may be modified by an ALTER SESSION statement, described in Oracle TimesTen In-Memory Database SQL Reference. If the attribute is specified in an ALTER SESSION statement in a database where PLSQL=0, an error is returned. For example

  ALTER SESSION SET PLSCOPE_STTINGS = 'IDENTIFIERS:ALL' ;
  

• If this attribute is specified in a connection string or in the odbc.ini file and the application is connecting to a database where PLSQL=0, no error or warning results.

PLSQL_CCFLAGS

This attribute sets directives to control conditional compilation of PL/SQL units, which enables you to customize the functionality of a PL/SQL program depending on conditions that are checked. This is especially useful when applications may be deployed to multiple database environments. Possible uses include activating debugging or tracing features, or basing functionality on the version of the database.

Use this format:

PLSQL_CCFLAGS = 'v1:c1,v2:c2,...,vn:cn'

v1 has the form of an unquoted PL/SQL identifier. It is unrestricted and can be a reserved word or a keyword. The text is insensitive to case. Each one is known as a flag or flag name. Each vi can occur multiple times in the string, each occurrence can have a different flag value, and the flag values can be of different kinds.

c1 is one of the following: a PL/SQL boolean literal, a PLS_INTEGER literal, or the literal NULL. The text is insensitive to case. Each one is known as a flag value and corresponds to a flag name.

ALTER SESSION SET PLSQL_CCFLAGS = 'v1:c1,v2:c2,...,vn:cn';

PLSQL_CONN_MEM_LIMIT

This attribute specifies the maximum amount of process heap memory in megabytes that PL/SQL can use for the connection in which it is set.

Some things to consider when setting this attribute are:

• PL/SQL does not allocate this memory until or unless it is needed. Many PL/SQL programs require only a small amount of memory. How you write your application can determine memory requirements. For example, using large VARRAYs in PL/SQL code can require a lot of memory.

• If you attempt to allocate more memory than allowed, TimesTen returns an error.

• The value can be modified with the ALTER SESSION statement, described in Oracle TimesTen In-Memory Database SQL Reference. For example:

  ALTER SESSION SET PLSQL_CONN_MEM_LIMIT = 100;
  

See Oracle TimesTen In-Memory Database PL/SQL Developer's Guide for more information.

PLSQL_OPTIMIZE_LEVEL

This attribute specifies the optimization level to be used to compile PL/SQL library units. The higher the setting of this parameter, the more effort the compiler makes to optimize PL/SQL library units.

Some things to consider when setting this attribute are:

• The PLSQL_OPTIMIZE_LEVEL connection attribute determines the initial value of this attribute within a session. The value may be modified by an ALTER SESSION statement, described in Oracle TimesTen In-Memory Database SQL Reference. If the attribute is specified in an ALTER SESSION statement in a database where PLSQL=0, an error is returned. For example:

  ALTER SESSION SET PLSQL_OPTIMIZE_LEVEL = 2;
  

• If this attribute is specified in a connection string or in the odbc.ini file and the application is connecting to a database where PLSQL=0, no error or warning results.

PLSQL_TIMEOUT

This attribute controls how long (in seconds) PL/SQL program units, including PL/SQL procedures, anonymous blocks and functions, are allowed to run before being automatically terminated.

This value may be modified with an ALTER SESSION statement, described in Oracle TimesTen In-Memory Database SQL Reference. If this value is modified through ALTER SESSION, the new value impacts any PL/SQL program units that are currently running. For example:

ALTER SESSION SET PLSQL_TIMEOUT = 10;

CacheAWTMethod

Determines whether asynchronous writethrough propagation uses the PL/SQL execution method or SQL array execution method to apply changes to the Oracle database server.

By default, asynchronous writethrough (AWT) uses PL/SQL execution method, CacheAWTMethod=1. AWT bundles all pending operations into a single PL/SQL collection that is sent to the Oracle database server to be executed. This method can improve AWT throughput when there are mixed transactions and network latency between TimesTen and the Oracle database server.

The SQL array execution to apply changes within TimesTen to the Oracle database works well when the same type of operation is repeated. For example, array execution is very efficient when a user does an update that affects several rows of the table. Updates are grouped together and sent to the Oracle database server in one batch.

PL/SQL execution method transparently falls back to array execution mode temporarily when it encounters one of the following:

• A statement that is over 32761 bytes in length.

• A statement that references a column of type BINARY FLOAT, BINARY DOUBLE and VARCHAR of length greater than 4000 bytes.

Specify the SQL execution method, CacheAWTMethod=0, if any AWT cache group contains a VARBINARY column.

The SYSTEMSTATS table contains information about the number of times the execution method temporarily falls back to SQL array execution.

CacheAWTParallelism

CacheAWTParallelism indicates the number of threads that apply changes to the Oracle database. This attribute has a relationship to ReplicationParallelism and ReplicationApplyOrdering. The default is 1.

If you do not set this attribute or if you set it to the default value of 1, the number of threads that apply changes to the Oracle database is twice the setting for ReplicationParallelism. If the CacheAWTParallelism attribute is set to 1 or not set, the maximum allowable value for ReplicationParallelism is 16.

If both ReplicationParallelism and CacheAWTParallelism attributes are set, the value set in CacheAWTParallelism configures the number of threads used for parallel propagation. The setting for CacheAWTParallelism determines the number of apply threads for parallel propagation and the setting for ReplicationParallelism determines the number of threads for parallel replication.

To learn more about parallel AWT caching, see "Configuring parallel propagation to Oracle Database tables" in the Oracle TimesTen Application-Tier Database Cache User's Guide.

CacheGridEnable

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

CacheGridMsgWait

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

The maximum wait time includes the value of this attribute added to the value of LockWait connection attribute.

For more information on caching data from an Oracle database in a TimesTen cache grid, see Oracle TimesTen Application-Tier Database Cache User's Guide.

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.

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 cache 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 Oracle TimesTen Application-Tier Database Cache User's Guide.

OracleNetServiceName

The TimesTen Cache uses the OracleNetServiceName attribute.

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.

OraclePWD

The TimesTen Cache uses the OraclePWD attribute.

The value of this attribute is the password for the user specified by UID to connect to the Oracle database to perform cache operations.

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

% ttisql
 
Copyright (c) 1996-2011, 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> 

PassThrough

The TimesTen Cache uses the PassThrough attribute.

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 TimesTen Cache, see Oracle TimesTen Application-Tier 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 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".

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 Cache.

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

TCP_Port

When connecting to a TimesTen database using the TimesTen Client and Server, the TimesTen Client requires the network address and the TCP port number of the computer running the TimesTen Server. As a convenience, TimesTen enables you to define a logical server name that contains the network address and port number pair.

If you specify anything other than a logical server name for the TTC_Server attribute in the Client DSN definition, TimesTen Client assumes that the Server is running on the default TCP/IP port number. In such cases, if your Server is running on a port other than the default port, you must specify the port number in the ODBC connection string. For example:

"TTC_SERVER=server_host_name;
 TTC_SERVER_DSN=Server_DSN;TCP_PORT=server_port"

or

"DSN=Client_DSN;TCP_Port=server_port"

TCP_Port2

TimesTen uses this attribute to specify the port number to use if an automatic failover occurs. See the description of TCP_Port for details on setting the value of this attribute and associated attributes.

See Oracle TimesTen In-Memory Database Operations Guide for more information on automatic client failover.

TTC_FailoverPortRange

Specifies a port range for the port that the automatic client failover thread listens on for failover notifications in an active/standby replication configuration. The failover configuration enables a client application to connect to a new active node automatically if there is a failure on the current node.

Specifying a port range helps accommodate firewalls between the client and server systems. By default, TimesTen uses a port chosen by the operating system.

See Oracle TimesTen In-Memory Database Operations Guide for more information on automatic client failover.

TTC_Server

When connecting to a TimesTen database using the TimesTen Client and Server, the TimesTen Client requires the specification of the network address and TCP port number of the computer running the TimesTen Server. As a convenience, TimesTen enables you to define a logical server name that contains the network address and port number pair. If you specify anything other than a logical server name for this attribute, TimesTen Client assumes that the Server is running on the default TCP/IP port number. In such cases, if your Server is running on a port other than the default port, you must specify the port number in the ODBC connection string. For example:

"TTC_SERVER=server_host_name;
 TTC_SERVER_DSN=Server_DSN;TCP_PORT=server_port"

or:

"DSN=Client_DSN;TCP_Port=server_port"

Once the logical server name is defined, you can use that name as the value for the TTC_Server attribute in a Client DSN. Multiple Client DSNs referencing the same computer that is running the TimesTen Server can use the same logical server name for the value of the TTC_Server attribute instead of having to specify repeatedly the same network address and port number within each of the Client DSNs.

"TTC_SERVER=server_host_name;TTC_SERVER_DSN=Server_DSN;
TCP_PORT=server_port"

"DSN=Client_DSN;TCP_Port=server_port"

TTC_Server2

This attribute specifies the logical server name to use if an automatic failover occurs. See the description of TTC_Server for details on setting the value of this attribute and associated attributes.

The value of this attribute can be the same as the value specified for TTC_Server if it is a virtual IP address.

If the client has already failed over and has connected to TTC_Server2 and the connection fails, it connects to TTC_Server. It alternately attempts to connect to TTC_Server and TTC_Server2 until the TTC_TIMEOUT attribute expires.

See Oracle TimesTen In-Memory Database Operations Guide for more information on automatic client failover.

TTC_Server_DSN

The TTC_Server_DSN attribute specifies a Server DSN on the computer running the TimesTen Server.

On Windows, Server DSNs are the set of TimesTen System DSNs that use the TimesTen Data Manager driver. Use the ODBC Data Source Administrator to define Server DSNs.

On UNIX, Server DSNs are defined in the /var/TimesTen/ instance/sys.odbc.ini file. More details on this topic can be found in the platform-specific sections.

TTC_Server_DSN2

This attribute specifies the Server DSN on the computer running the TimesTen Server. This is the Server DSN to be used if an automatic failover occurs. See the description of TTC_Server_DSN for details on setting the value of this attribute and associated attributes.

If a failover occurs, if the client cannot connect to TTC_Server_DSN or loses the connection to the DSN, it attempts to connect to TTC_Server_DSN2.

See Oracle TimesTen In-Memory Database Operations Guide for more information on automatic client failover.

TTC_Timeout

The TTC_Timeout attribute sets a maximum time limit, in seconds, for a network operation that is completed by using the TimesTen Client and Server. The TTC_Timeout attribute also determines the maximum number of seconds a TimesTen Client application waits for the result from the corresponding TimesTen Server process before timing out.

The operating systemselect() call on the client side of a CLIENT/SERVER connection uses the value of TTC_TIMEOUT. The SQLExecute() and OCIStmtExecute() functions do not use the value of this attribute.

A value of 0 indicates that client/server operations should not timeout. Setting of this attribute is optional. If this attribute is not set, the default timeout period is 60 seconds. The maximum timeout period is 99,999 seconds. Upon timeout, the operation is interrupted, the Client application receives a timeout error and the connection is terminated. For example, if the Client application is running long queries, you may want to increase the timeout interval.

For active standby pair failover scenarios, the minimum value is 60 seconds.

If you are using PL/SQL, set the PLSQL_TIMEOUT value to a value that is at least 5 seconds less than TTC_TIMEOUT.

The query timeout can be set using the SQLSetConnectOption ODBC call before a connection is established to the database using either the SQLConnect or SQLDriverConnect ODBC calls. Alternatively, the query timeout can be set by calling either the SQLSetConnectOption or SQLSetStmtOption ODBC calls after a connection is established to the database.

When the query timeout is set before establishing a connection to the database, the client driver does not know the network timeout value at that point. Hence, later, at connect time, the client driver silently sets the query timeout to a value slightly smaller than the network timeout value if the following are true:

• The network timeout value is greater than 0.

• The query timeout value was 0, or greater than or equal to the network timeout value.

The timeout value can be set after establishing a connection by calling the ttIsql clienttimeout command. When the query timeout is set after establishing a connection to the database, the client driver returns an error if the network timeout value is greater than 0, and the query timeout value greater than or equal to the network timeout value. The SQLState is set to S1000.

This attribute is not supported when shared memory is used for Client/Server inter-process communication. If set, TimesTen ignores the attribute.

MaxConnsPerServer

The MaxConnsPerServer attribute sets the maximum number of concurrent connections to the server which the DSN references.

If you want to support many connections to the Server, you must ensure that the per-process file descriptor limit for the UID that TimesTen is being run as is set to a value somewhat more than the number of concurrent child servers that are active. This is the number of anticipated concurrent client connections divided by MaxConnsPerServer.

The value of this attribute takes precedence over the setting of the value of the -maxConnsPerServer option in the ttendaemon.options file. For details, see "Specifying multiple connections to the TimesTen Server" in Oracle TimesTen In-Memory Database Operations Guide.

For limits on the maximum number of connections to a TimesTen database, see Chapter 4, "System Limits".

ServersPerDSN

The ServersPerDSN attribute specifies the number of child server processes for a particular server DSN that will use round-robin connection distribution.This attribute only has any effect if the TimesTen server is configured to operate in multithreaded mode (MaxConnsPerServer > 1). If ServersPerDSN is set to 1 then the first MaxConnsPerServer client connections to the server DSN will be assigned to one child server process, the next MaxConnsPerServer connections to a second child server process and so on.If ServersPerDSN is set to N where N > 1 then the first N * MaxConnsPerServer client connections to the server DSN are distributed in round robin fashion over N child server processes. If additional client connections beyond N * MaxConnsPerServer are opened to the same server DSN then those connections are assigned to new child server processes sequentially as for the case when ServersPerDSN=1.If this attribute is set in a server DSN definition then it will override, for that server DSN only, any value specified for the -serversPerDSN daemon option (specified in the ttendaemon.options file). If neither -serversPerDSN nor ServersPerDSN are configured then TimesTen uses the default value of 1. For further details, see "Specifying multiple connections to the TimesTen Server" in Oracle TimesTen In-Memory Database Operations Guide.

ServerStackSize

The ServerStackSize attribute value determines the size of the stack on the Server for each connection. The value of this attribute is only meaningful if the value of MaxConnsPerServer is greater than one. If there is only one connection per Server, the child server uses the process' main stack. It is also platform-dependent, as defined in the setting below.

This value of this attribute takes precedence over the setting of the -serverStackSize option in the ttendaemon.options file. For details, see "Specifying multiple connections to the TimesTen Server" in Oracle TimesTen In-Memory Database Operations Guide.

Changes to TimesTen Server settings do not occur until the TimesTen server is restarted. To restart the Server, use the command ttDaemonAdmin -restartserver.