First connection attributes

First connection attributes

First connection attributes are set when a connection is made to an idle data store (a data store created by the instance administrator which currently has no connections) and persist for that connection and all subsequent connections until the last connection to this data store is closed.

First connection attributes are listed in Table 1–2, " First connection attributes" and described in detail in this section.

If you try to connect to the data store using attributes that are different from the first connection attribute settings, the new connection may be rejected or the attribute value may be ignored. However, for example, if existing connections have a LogFileSize of one size and a new connection specifies a LogFileSize of another size, TimesTen ignores the new value and returns a warning.

Note: Only the instance administrator can change a first connection attribute to a value other than the one currently in effect. To change the value of a first connection attribute, you must first shut down the data store.

Data Store Attributes 1-23

AutoCreate

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

Required privilege

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

Setting

Set AutoCreate as follows: Where to set the

attribute

How the attribute is

represented Setting

C or Java programs or UNIX ODBC.INI file

AutoCreate 0 - Does not create new data store if data store does not exist.

1 - Creates new data store if data store does not exist (default). Windows ODBC Data Source Administrator AutoCreate check box

unchecked - Does not create new data store if data store does not exist.

checked - Creates new data store if data store does not exist (default).

CkptFrequency

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 data store loads and unloads unless it is explicitly changed. The default value is only used during data store creation. Subsequent first connections default to using the existing value stored in the data store. If left unspecified (or empty in the Windows ODBC Data Source

Administrator), the stored setting is used. To turn the attribute off, you must explicitly specify a value of 0.

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.

Required privilege

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

Setting

Set CkptFrequency as follows:

Where to set the attribute

How the attribute is

represented Setting

C or Java programs or UNIX ODBC.INI file

CkptFrequency Enter a value in seconds for the frequency at which TimesTen should perform a background checkpoint. Default is 600 if Logging=1 is specified, otherwise it is 0. To specify the default or "existing" value, leave the value empty. A value of 0 means that checkpoint frequency is not considered when scheduling checkpoints.

Data Store Attributes 1-25

Windows ODBC Data Source Administrator

Ckpt Frequency (secs) field Enter a value in seconds for the frequency at which TimesTen should perform a background checkpoint. Default is 600 if Logging=1 is specified, otherwise it is 0. To specify the default or

"existing" value, leave the field empty. A value of 0 means that checkpoint frequency is not considered when scheduling checkpoints.

Where to set the attribute

How the attribute is

CkptLogVolume

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 data store loads and unloads unless it is explicitly changed. The default value is only used during data store creation. Subsequent first connections default to using the existing value stored in the data store. If left unspecified (or empty in the Windows ODBC Data Source

Administrator), the stored setting is used. To turn the attribute off, you must explicitly specify a value of 0.

Required privilege

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

Setting

Set CkptLogVolume as follows:

Where to set the attribute

How the attribute is

represented Setting

C or Java programs or UNIX ODBC.INI file

CkptLogVolume Specify the amount of data in megabytes that can

accumulate in the transaction log file between background checkpoints. The default is 0. To specify the default or "existing" value, leave the value empty. A value of 0 means that log volume is not considered when scheduling checkpoints.

Windows ODBC Data Source Administrator

Ckpt LogVolume field Specify the amount of data in megabytes that can

accumulate in the transaction log file between background checkpoints. The default is 0. To specify the default or "existing" value, leave the field empty. A value of 0 means that log volume is not

Data Store Attributes 1-27

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.

This rate is used by all background checkpoints and by checkpoints initiated by the

ttCkpt and ttCkptBlocking built-in procedures. 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 data store loads and unloads unless it is explicitly changed. The default value is only used during data store creation. Subsequent first connections default to using the existing value stored in the data store. If left unspecified (or empty in the Windows ODBC Data Source

Administrator), the stored setting is used. To turn the attribute off, you must explicitly specify a value of 0. For existing data stores 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 for background checkpoints" in Oracle TimesTen In-Memory Database Operations Guide.

Required privilege

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

Setting

Set CkptRate as follows:

Where to set the attribute

How the attribute is

represented Setting

C or Java programs or UNIX ODBC.INI file

CkptRate Specify the maximum rate in MB per second at which a checkpoint should be written to disk. A value of 0 indicates that the rate should not be limited. This is the default. Windows ODBC Data Source

Administrator

CkptRate field Specify the maximum rate in MB per second at which a checkpoint should be written to disk. A value of 0 indicates that the rate should not be limited. This is the default.