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Berkeley DB: Db::cursor
Db::cursor
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#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 to which
cursorp refers.
If the operation is to be transaction-protected, the txnid
parameter is a transaction handle returned from DbEnv::txn_begin;
otherwise, NULL.
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
used.
The flags value must be set to 0 or by bitwise inclusively OR'ing together one or
more of the following values:
- DB_DIRTY_READ
- 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.
- DB_WRITECURSOR
- Specify that the cursor will be used to update the database. The
underlying database environment must have been opened using the
DB_INIT_CDB flag.
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::associate,
Db::close,
Db::cursor,
Db::del,
Db::err, Db::errx
Db::fd,
Db::get,
Db::pget,
Db::get_byteswapped,
Db::get_type,
Db::join,
Db::key_range,
Db::open,
Db::put,
Db::remove,
Db::rename,
Db::set_alloc,
Db::set_append_recno,
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_feedback,
Db::set_flags,
Db::set_h_ffactor,
Db::set_h_hash,
Db::set_h_nelem,
Db::set_lorder,
Db::set_pagesize,
Db::set_paniccall,
Db::set_q_extentsize,
Db::set_re_delim,
Db::set_re_len,
Db::set_re_pad,
Db::set_re_source,
Db::stat,
Db::sync,
Db::truncate,
Db::upgrade,
and
Db::verify.
Copyright Sleepycat Software
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