txn_begin |
![]() ![]() |
#include <db.h>int txn_begin(DB_ENV *env, DB_TXN *parent, DB_TXN **tid, u_int32_t flags);
The txn_begin method creates a new transaction in the environment and copies a pointer to a DB_TXN that uniquely identifies it into the memory referenced by tid.
If the parent argument is non-NULL, the new transaction will be a nested transaction, with the transaction indicated by parent as its parent. Transactions may be initiated in threads of control other than the parent's and may be nested to any level.
The flags parameter must be set to 0 or one of the following values:
This behavior may be set for an entire Berkeley DB environment as part of the DBENV->set_flags interface.
This behavior is the default for Berkeley DB environments unless the DB_TXN_NOSYNC flag was specified to the DBENV->set_flags interface.
Note: While child transactions may be initiated in threads of control other than the parent's, an individual transaction may not span threads, i.e., each transaction must begin and end in the same thread, and each transaction may only be used by a single thread.
Note: cursors may not span transactions, i.e., each cursor must be opened and closed within a single transaction.
Note: a parent transaction may not issue any Berkeley DB operations, except for txn_begin, txn_abort and txn_commit, while it has active child transactions (child transactions that have not yet been committed or aborted).
The txn_begin function returns a non-zero error value on failure and 0 on success.
The txn_begin function may fail and return a non-zero error for the following conditions:
The txn_begin function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the txn_begin function may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.
![]() ![]() |