Berkeley DB: Db::cursor
Description: Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++

# Db::cursor |

`

###

    #include <db_cxx.h>

    int
    Db::cursor(DbTxn *txnid, Dbc **cursorp, u_int32_t flags);

# Description

The Db::cursor method creates a cursor and copies a pointer to it into the memory referenced by cursorp.

If the file is being accessed under transaction protection, the txnid parameter is a transaction ID returned from DbEnv::txn_begin, otherwise, NULL.

If transaction protection is enabled, 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 used.

The flags value must be set to 0 or by bitwise inclusively OR'ing together one or more of the following values.

DB_WRITECURSOR
  Specify that the cursor will be used to update the database. This flag should only be set when the DB_INIT_CDB flag was specified to DbEnv::open.

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.

# Errors

The Db::cursor method may fail and throw an exception or return a non-zero error for the following conditions:

EINVAL
  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 an exception encapsulating DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

### Class

Db

# See Also

Db::close, Db::cursor, Db::del, Db::err, Db::fd, Db::get, Db::get_byteswapped, Db::get_type, Db::join, Db::key_range, Db::open, Db::put, Db::remove, Db::set_bt_compare, Db::set_bt_minkey, Db::set_bt_prefix, Db::set_cachesize, Db::set_dup_compare, Db::set_errcall, Db::set_errfile, Db::set_errpfx, Db::set_flags, Db::set_h_ffactor, Db::set_h_hash, Db::set_h_nelem, Db::set_lorder, Db::set_malloc, Db::set_pagesize, Db::set_paniccall, Db::set_q_extentsize, Db::set_realloc, Db::set_re_delim, Db::set_re_len, Db::set_re_pad, Db::set_re_source, Db::stat, Db::sync, Db::upgrade and Db::verify.`

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