Berkeley DB: DbTxnMgr.begin
Description: Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,b+tree,btr ee,hash,hashing,transaction,transactions,locking,logging,access method,access me thods,java,C,C++

# DbTxnMgr.begin

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    import com.sleepycat.db.*;

    public DbTxn begin(DbTxn pid)
    	throws DbException;

# Description

The DbTxnMgr.begin method creates a new transaction in the transaction manager, and returns a DbTxn that uniquely identifies it.

Note: transactions 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: transactions may not span cursors, i.e., each transaction may only be used by a single cursor.

Note: transactions may not currently be nested. In a future revision of Berkeley DB, if the pid argument is non-null, the new transaction will be a nested transaction, with the transaction indicated by pid as its parent.

The DbTxnMgr.begin method throws an exception that encapsulates an errno on failure.

# Errors

If a fatal error occurs in Berkeley DB, the DbTxnMgr.begin method may fail and throw a DbRunRecoveryException, at which point all subsequent database calls will also fail in the same way.

The DbTxnMgr.begin method may fail and throw an exception for any of the errors specified for the following Berkeley DB and C library functions: abort(3), fcntl(3), fflush(3), fprintf(3), free(3), fsync(3), getpid(3), DbLog.put, lseek(3), memset(3), mmap(3), munmap(3), shmat(3), shmdt(3), strerror(3), vfprintf(3), vsnprintf(3), and write(3).

In addition, the DbTxnMgr.begin method may fail and throw an exception encapsulating errno for the following conditions:

ENOSPC
  The maximum number of concurrent transactions has been reached.

# Class

DbTxnMgr

# See Also

DbTxnMgr.begin, DbTxnMgr.checkpoint, DbTxnMgr.close, DbTxnMgr.open, DbTxnMgr.stat and DbTxnMgr.unlink.`