Supporto di transazioni distribuite

Si applica a: SQL Server Database SQL di Azure Istanza gestita di SQL di Azure Azure Synapse Analytics Piattaforma di strumenti analitici (PDW)

Download del driver OLE DB

I consumer del driver OLE DB per SQL Server possono usare il metodo ITransactionJoin::JoinTransaction per partecipare a una transazione distribuita coordinata da Microsoft Distributed Transaction Coordinator (MS DTC).

MS DTC espone oggetti COM che consentono ai client di avviare e partecipare a transazioni coordinate tra più connessioni a un'ampia gamma di archivi dati. Per avviare una transazione, il consumer di OLE DB Driver per SQL Server usa l'interfaccia MS DTC ITransactionDispenser. Il membro BeginTransaction di ITransactionDispenser restituisce un riferimento in un oggetto della transazione distribuita. Tale riferimento viene passato a OLE DB Driver per SQL Server usando JoinTransaction.

MS DTC supporta il commit asincrono e l'interruzione nelle transazioni distribuite. Come notifica sullo stato della transazione asincrona, il consumer implementa l'interfaccia ITransactionOutcomeEvents e connette l'interfaccia a un oggetto transazione MS DTC.

Per le transazioni distribuite, il driver OLE DB per SQL Server implementa i parametri di ITransactionJoin::JoinTransaction nel modo seguente.

In questo esempio viene coordinata la transazione tramite MS DTC.

// Interfaces used in the example.  
IDBCreateSession*       pIDBCreateSession   = NULL;  
ITransactionJoin*       pITransactionJoin   = NULL;  
IDBCreateCommand*       pIDBCreateCommand   = NULL;  
IRowset*                pIRowset            = NULL;  
  
// Transaction dispenser and transaction from MS DTC.  
ITransactionDispenser*  pITransactionDispenser = NULL;  
ITransaction*           pITransaction       = NULL;  
  
    HRESULT             hr;  
  
// Get the command creation interface for the session.  
if (FAILED(hr = pIDBCreateSession->CreateSession(NULL,  
     IID_IDBCreateCommand, (IUnknown**) &pIDBCreateCommand)))  
    {  
    // Process error from session creation. Release any references and  
    // return.  
    }  
  
// Get a transaction dispenser object from MS DTC and  
// start a transaction.  
if (FAILED(hr = DtcGetTransactionManager(NULL, NULL,  
    IID_ITransactionDispenser, 0, 0, NULL,  
    (void**) &pITransactionDispenser)))  
    {  
    // Process error message from MS DTC, release any references,  
    // and then return.  
    }  
if (FAILED(hr = pITransactionDispenser->BeginTransaction(  
    NULL, ISOLATIONLEVEL_READCOMMITTED, ISOFLAG_RETAIN_DONTCARE,  
    NULL, &pITransaction)))  
    {  
    // Process error message from MS DTC, release any references,  
    // and then return.  
    }  
  
// Join the transaction.  
if (FAILED(pIDBCreateCommand->QueryInterface(IID_ITransactionJoin,  
    (void**) &pITransactionJoin)))  
    {  
    // Process failure to get an interface, release any references, and  
    // then return.  
    }  
if (FAILED(pITransactionJoin->JoinTransaction(  
    (IUnknown*) pITransaction, 0, 0, NULL)))  
    {  
    // Process join failure, release any references, and then return.  
    }  
  
// Get data into a rowset, then update the data. Functions are not  
// illustrated in this example.  
if (FAILED(hr = ExecuteCommand(pIDBCreateCommand, &pIRowset)))  
    {  
    // Release any references and return.  
    }  
  
// If rowset data update fails, then terminate the transaction, else  
// commit. The example doesn't retain the rowset.  
if (FAILED(hr = UpdateDataInRowset(pIRowset, bDelayedUpdate)))  
    {  
    // Get error from update, then abort.  
    pITransaction->Abort(NULL, FALSE, FALSE);  
    }  
else  
    {  
    if (FAILED(hr = pITransaction->Commit(FALSE, 0, 0)))  
        {  
        // Get error from failed commit.  
        //  
        // If a distributed commit fails, application logic could  
        // analyze failure and retry. In this example, terminate. The   
        // consumer must resolve this somehow.  
        pITransaction->Abort(NULL, FALSE, FALSE);  
        }  
    }  
  
if (FAILED(hr))  
    {  
    // Update of data or commit failed. Release any references and  
    // return.  
    }  
  
// Un-enlist from the distributed transaction by setting   
// the transaction object pointer to NULL.  
if (FAILED(pITransactionJoin->JoinTransaction(  
    (IUnknown*) NULL, 0, 0, NULL)))  
    {  
    // Process failure, and then return.  
    }  
  
// Release any references and continue.  

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