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 |

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    #include <db.h>

    int
    DB->cursor(DB *db,
        DB_TXN *txnid, DBC **cursorp, u_int32_t flags);

# Description

The DB->cursor function 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 DB_ENV->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 function returns a non-zero error value on failure and 0 on success.

# Errors

The DB->cursor function may fail and return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

The DB->cursor 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 DB->cursor function may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

# See Also

db_create, 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.`

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