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/* Copyright (C) 2003 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*****************************************************************************
* Name: NdbResultSet.hpp
* Include:
* Link:
* Author: Martin Sköld
* Date: 2002-04-01
* Version: 0.1
* Description: Cursor class
* Documentation:
* Adjust: 2002-04-01 Martin Sköld First version.
****************************************************************************/
#ifndef NdbResultSet_H
#define NdbResultSet_H
#include <NdbScanOperation.hpp>
/**
* @class NdbResultSet
* @brief NdbResultSet contains a NdbScanOperation.
*/
class NdbResultSet
{
friend class NdbScanOperation;
public:
/**
* Get the next tuple in a scan transaction.
*
* After each call to NdbResult::nextResult
* the buffers and NdbRecAttr objects defined in
* NdbOperation::getValue are updated with values
* from the scanned tuple.
*
* @param fetchAllowed If set to false, then fetching is disabled
*
* The NDB API will contact the NDB Kernel for more tuples
* when necessary to do so unless you set the fetchAllowed
* to false.
* This will force NDB to process any records it
* already has in it's caches. When there are no more cached
* records it will return 2. You must then call nextResult
* with fetchAllowed = true in order to contact NDB for more
* records.
*
* fetchAllowed = false is useful when you want to update or
* delete all the records fetched in one transaction(This will save a
* lot of round trip time and make updates or deletes of scanned
* records a lot faster).
* While nextResult(false)
* returns 0 take over the record to another transaction. When
* nextResult(false) returns 2 you must execute and commit the other
* transaction. This will cause the locks to be transferred to the
* other transaction, updates or deletes will be made and then the
* locks will be released.
* After that, call nextResult(true) which will fetch new records and
* cache them in the NdbApi.
*
* @note If you don't take over the records to another transaction the
* locks on those records will be released the next time NDB Kernel
* is contacted for more records.
*
* @note Please contact for examples of efficient scan
* updates and deletes.
*
* @note See ndb/examples/ndbapi_scan_example for usage.
*
* @return
* - -1: if unsuccessful,<br>
* - 0: if another tuple was received, and<br>
* - 1: if there are no more tuples to scan.
* - 2: if there are no more cached records in NdbApi
*/
int nextResult(bool fetchAllowed = true, bool forceSend = false);
/**
* Close result set (scan)
*/
void close(bool forceSend = false);
/**
* Restart
*/
int restart(bool forceSend = false);
/**
* Transfer scan operation to an updating transaction. Use this function
* when a scan has found a record that you want to update.
* 1. Start a new transaction.
* 2. Call the function takeOverForUpdate using your new transaction
* as parameter, all the properties of the found record will be copied
* to the new transaction.
* 3. When you execute the new transaction, the lock held by the scan will
* be transferred to the new transaction(it's taken over).
*
* @note You must have started the scan with openScanExclusive
* to be able to update the found tuple.
*
* @param updateTrans the update transaction connection.
* @return an NdbOperation or NULL.
*/
NdbOperation* updateTuple();
NdbOperation* updateTuple(NdbConnection* updateTrans);
/**
* Transfer scan operation to a deleting transaction. Use this function
* when a scan has found a record that you want to delete.
* 1. Start a new transaction.
* 2. Call the function takeOverForDelete using your new transaction
* as parameter, all the properties of the found record will be copied
* to the new transaction.
* 3. When you execute the new transaction, the lock held by the scan will
* be transferred to the new transaction(its taken over).
*
* @note You must have started the scan with openScanExclusive
* to be able to delete the found tuple.
*
* @param deleteTrans the delete transaction connection.
* @return an NdbOperation or NULL.
*/
int deleteTuple();
int deleteTuple(NdbConnection* takeOverTransaction);
/**
* Get underlying operation
*/
NdbOperation* getOperation();
private:
NdbResultSet(NdbScanOperation*);
~NdbResultSet();
void init();
NdbScanOperation* m_operation;
};
inline
NdbOperation*
NdbResultSet::getOperation(){
return m_operation;
}
#endif
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