Database Link Properties#

DBLINK_ALTILINKER_CONNECT_TIMEOUT (Unit: second)#

Data Type#

Unsigned Integer

Default Value#

100

Attributes#

Read-Only, Single Value

Range#

[0, 2³²-1]

Description#

This property specifies the connection timeout, in seconds, when the Altibase server attempts to establish a connection to AltiLinker.

DBLINK_DATA_BUFFER_ALLOC_RATIO#

Data Type#

Unsigned Integer

Default Value#

50

Attributes#

Read-Only, Single Value

Range#

[0, 1]

Description#

This is the space in which the local server retrieves and stores the result sets of a query executed on a remote server through a database link. This is called the database link-exclusive data buffer. This property specifies the ratio of the record buffer to be allocated per query for the remaining space in the database link-exclusive data buffer.

DBLINK_DATA_BUFFER_BLOCK_COUNT#

Data Type#

Unsigned Integer

Default Value#

128

Attributes#

Read-Only, Single Value

Range#

[0, 2¹²-1]

Description#

This is the space in which the local server retrieves and stores the result sets of a query executed on a remote server through a database link. This is called the database link-exclusive data buffer. This property specifies the initial number of allocations for record buffer blocks that compose the data buffer. The size of the data buffer is DBLINK_DATA_BUFFER_BLOCK_COUNT * DBLINK_DATA_BUFFER_BLOCK_SIZE.

DBLINK_DATA_BUFFER_BLOCK_SIZE (Unit: byte)#

Data Type#

Unsigned Integer

Default Value#

2 MBytes

Attributes#

Read-Only, Single Value

Range#

[0, 29]

Description#

This is the space in which the local server retrieves and stores the result sets of a query executed on a remote server through a database link. This is called the database link-exclusive data buffer. This property specifies the size, in bytes, of the record buffer block which composes the data buffer.

DBLINK_ENABLE#

Data Type#

Unsigned Integer

Default Value#

0

Attributes#

Read-Write, Single Value

Range#

[0, 1]

Description#

This property specifies the AUTOCOMMIT mode of the remote database. This property is only applied when the DBLINK_GLOBAL_TRANSACTION_LEVEL is set to 0.

0: Autocommit-Off

1: Autocommit-On

DBLINK_GLOBAL_TRANSACTION_LEVEL#

Data Type#

Unsigned Integer

Default Value#

1

Attributes#

Read-Only, Single Value

Range#

[0, 2]

Description#

This property specifies the execution level of the global transaction. When this property is set to 0, the DBLINK_REMOTE_STATEMENT_AUTOCOMMIT property must be set to correspond to the AUTOCOMMIT mode of the remote database.

0: Remote Statement Execution Level

This level perceives each transaction on servers(local and remote servers) participating in one global transaction as separate transactions, so the transactions must be respectively committed at the local and remote servers in order to commit the global transaction. Even if a global transaction is in this level, a COMMIT performed on the local server does not affect the remote server.
1: Simple Transaction Commit Level

This level perceives all transactions on servers(local and remote servers) participating in one global transaction as one transaction. Therefore, if a global transaction is committed on a local server, all transactions participating in the global transaction are committed..
2:Two-Phase Commit (2PC) Level

At this level, the 2PC protocol is supported to ensure transaction consistency of database systems that participating in one global transaction. If a global transaction begins, this property cannot be changed until the end of the transaction.

DBLINK_RECOVERY_MAX_LOGFILE#

Data Type#

Unsigned Integer

Default Value#

0

Attributes#

Read-Write, Single Value

Range#

[1, 2³²-1]

Description#

This property specifies the maximum number of log files that Altibase HDB maintains or distributed transaction recovery when a heterogeneous database system fails during a transaction.

If this property value is 0, consistency is guaranteed because the log for distributed transaction recovery is not deleted.

However, if the property value is set to a value greater than 1, consistency cannot be guaranteed because the log is deleted by a checkpoint even if the distributed transaction is not completed when the number of log files is exceeded.

The value of this property can be changed using the ALTER SYSTEM statement while Altibase is running.

DBLINK_REMOTE_STATEMENT_AUTOCOMMIT#

Data Type#

Unsigned Integer

Default Value#

0

Attributes#

Read-Write, Single Value

Range#

[0, 1]

Description#

This property specifies the AUTOCOMMIT mode of the remote database. This property is only applied when the DBLINK_GLOBAL_TRANSACTION_LEVEL is set to 0.

0: Autocommit-Off

1: Autocommit-On

DBLINK_REMOTE_TABLE_BUFFER_SIZE (Unit: MB)#

Data Type#

Unsigned Integer

Default Value#

50

Attributes#

Read-Write, Single Value

Range#

[0, 2³²-1]

Description#

This is a memory buffer which can temporarily store query results if a query is executed through REMOTE_TABLE keyword in the remote server.

The stored query results are deleted after being delivered to a query processor. However, the property value should be adjusted since it cannot be specified if one of records of the result set is larger than the specified size.