Db::cursor(DbTxn *txnid, Dbc **cursorp, u_int32_t flags);
The Db::cursor method
creates a cursor and copies a pointer to it into the memory to which
If the operation is to be transaction-protected, the txnid
parameter is a transaction handle returned from DbEnv::txn_begin;
To transaction-protect cursor operations, cursors must be opened and
closed within the context of a transaction, and the txnid
parameter specifies the transaction context in which the cursor may be
The flags value must be set to 0 or by bitwise inclusively OR'ing together one or
more of the following values:
- All read operations performed by the cursor may return modified but not
yet committed data. Silently ignored if the DB_DIRTY_READ flag
was not specified when the underlying database was opened.
- Specify that the cursor will be used to update the database. The
underlying database environment must have been opened using the
The Db::cursor method either returns a non-zero error value or throws an exception that
encapsulates a non-zero error value on failure, and returns 0 on success.
The Db::cursor method may fail and throw an exception or return a non-zero error for the following conditions:
- An invalid flag value or parameter was specified.
The Db::cursor method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods.
If a catastrophic error has occurred, the Db::cursor method may fail and
either return DB_RUNRECOVERY or throw a
in which case all subsequent Berkeley DB calls will fail in the same way.
Database Cursors and Related Methods
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