.I&Berkeley DB: Db::cursor[P

Db::cursor





#include <db_cxx.h>

int9Db::cursor(DbTxn *txnid, Dbc **cursorp, u_int32_t flags);





Description



The Db::cursor methodFcreates a cursor and copies a pointer to it into the memory referencedby cursorp.

MA cursor is a structure used to provide sequential access through a database.FThis interface and its associated functions replaces the functionalityHprovided by the seq function in previous releases of Berkeley DB.

;If the file is being accessed under transaction protection,<the txnid parameter is a transaction ID returned fromQDbTxnMgr::begin, otherwise, NULL.GIf transaction protection is enabled, cursors must be opened and closedCwithin the context of a transaction, and the txnid parameterBspecifies the transaction context in which the cursor may be used.

,The flags parameter must be set to 0.

RIn addition, the following value may be set by logically OR'ing it into theflags parameter:

S

DB_RMW
Specify that the cursor will be used to update the database. Thissflag should only be set when the DB_INIT_CDB flagOwas specified to DbEnv::appinit.


The Db::cursor>method either returns errno or throws an exception that:encapsulates an errno on failure, and 0 on success.



Errors

QIf a fatal error occurs in Berkeley DB, the Db::cursor method may fail and eitherIreturn DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY,Gat which point all subsequent database calls will also fail in the sameFway. Methods marked as returning errno will, by default, throwHan exception that encapsulates the error information. The default error\behavior can be changed, see DbException.

The Db::cursor&method may fail and throw an exceptionKfor any of the errors specified for the following Berkeley DB and C library functions:__ham_c_init(3),free(3),<DbLockTab::id, malloc(3), memcpy(3),and memset(3).

In addition, the Db::cursor&method may fail and throw an exceptionor return errnofor the following conditions:

B

EINVAL
An invalid flag value or parameter was specified.







Class

,Db



See Also

4Db::close, Db::cursor,0Db::del,.Db::fd,0Db::get,HDb::get_byteswapped,:Db::get_type,2Db::join,2Db::open,0Db::put,1Db::statand2Db::sync.
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