Library Version 11.2.5.3

Library Version 12.1.6.1

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The application may change the number of simultaneous outstanding -transactions supported by the Berkeley DB environment by calling the -DB_ENV->set_tx_max() method. This will also set the size of the -underlying transaction subsystem's region. When the number of -outstanding transactions is reached, additional calls to -DB_ENV->txn_begin() will fail until some active transactions complete.

The application can limit how long a transaction runs or blocks on -contested resources. -The DB_ENV->set_timeout() method specifies the length of the timeout. -This value is checked whenever deadlock detection is performed or -when the transaction is about to block on a lock that cannot be -immediately granted. -Because timeouts are only checked at these times, the accuracy of the -timeout depends on how often deadlock detection is performed or how -frequently the transaction blocks.

There is an additional parameter used in configuring transactions; the -DB_TXN_NOSYNC. Setting the DB_TXN_NOSYNC flag to -DB_ENV->set_flags() when opening a transaction region changes the -behavior of transactions to not write or synchronously flush the log -during transaction commit.

This change may significantly increase application transactional -throughput. However, it means that although transactions will continue -to exhibit the ACI (atomicity, consistency, and isolation) properties, -they will not have D (durability). Database integrity will be -maintained, but it is possible that some number of the most recently -committed transactions may be undone during recovery instead of being -redone.

+ The application may change the number of simultaneous + outstanding transactions supported by the Berkeley DB + environment by calling the DB_ENV->set_tx_max() method. This will + also set the size of the underlying transaction subsystem's + region. When the number of outstanding transactions is + reached, additional calls to DB_ENV->txn_begin() will fail until some + active transactions complete. +

+ The application can limit how long a transaction runs or + blocks on contested resources. The DB_ENV->set_timeout() method + specifies the length of the timeout. This value is checked + whenever deadlock detection is performed or when the + transaction is about to block on a lock that cannot be + immediately granted. Because timeouts are only checked at + these times, the accuracy of the timeout depends on how often + deadlock detection is performed or how frequently the + transaction blocks. +

+ There is an additional parameter used in configuring + transactions; the DB_TXN_NOSYNC. Setting the DB_TXN_NOSYNC + flag to DB_ENV->set_flags() when opening a transaction region + changes the behavior of transactions to not write or + synchronously flush the log during transaction commit. +

+ This change may significantly increase application + transactional throughput. However, it means that although + transactions will continue to exhibit the ACI (atomicity, + consistency, and isolation) properties, they will not have D + (durability). Database integrity will be maintained, but it is + possible that some number of the most recently committed + transactions may be undone during recovery instead of being + redone. +

@@ -77,9 +85,7 @@ redone.

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