Ejemplo de la propiedad CacheSize (VC++)

Se aplica a: Access 2013, Office 2013

En este ejemplo se utiliza la propiedad CacheSize para mostrar la diferencia en términos de rendimiento entre una operación realizada con una memoria caché de 30 registros y una operación realizada sin caché.

 
// BeginCacheSizeCpp 
#import "C:\Program Files\Common Files\System\ADO\msado15.dll" no_namespace rename("EOF", "EndOfFile") 
 
#include <ole2.h> 
#include <stdio.h> 
#include <conio.h> 
#include <winbase.h> 
 
// Function declarations 
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);}; 
void CacheSizeX(); 
void PrintProviderError(_ConnectionPtr pConnection); 
void PrintComError(_com_error &e); 
 
/////////////////////////////////////////////////////////// 
// // 
// Main Function // 
// // 
/////////////////////////////////////////////////////////// 
 
void main() 
{ 
 if(FAILED(::CoInitialize(NULL))) 
 return; 
 
 CacheSizeX(); 
 
 //Wait here for user to see the output.. 
 printf("\nPress any key to continue..."); 
 getch(); 
 
 ::CoUninitialize(); 
} 
 
/////////////////////////////////////////////////////////// 
// // 
// CacheSizeX Function // 
// // 
/////////////////////////////////////////////////////////// 
 
void CacheSizeX() 
{ 
 // Define ADO object pointers. 
 // Initialize pointers on define. 
 // These are in the ADODB:: namespace 
 _RecordsetPtr pRstRoySched = NULL; 
 
 //Define Other Variables 
 HRESULT hr = S_OK; 
 DWORD sngStart; 
 DWORD sngEnd; 
 float sngNoCache; 
 float sngCache; 
 int intLoop = 0; 
 _bstr_t strTemp; 
 
 _bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';" 
 "Initial Catalog='pubs';Integrated Security='SSPI';"); 
 
 try 
 { 
 //Open the RoySched table. 
 TESTHR(pRstRoySched.CreateInstance(__uuidof(Recordset))); 
 pRstRoySched->Open("roysched", strCnn, adOpenForwardOnly, 
 adLockReadOnly, adCmdTable); 
 
 // Enumerate the Recordset object twice and record 
 // the elapsed time. 
 sngStart = GetTickCount(); 
 
 for (intLoop = 1; intLoop < 2; intLoop++) 
 { 
 pRstRoySched->MoveFirst(); 
 
 while(!(pRstRoySched->EndOfFile)) 
 { 
 // Execute a simple operation for the 
 // performance test. 
 strTemp = pRstRoySched->Fields-> 
 Item["title_id"]->Value; 
 pRstRoySched->MoveNext(); 
 } 
 } 
 sngEnd = GetTickCount(); 
 sngNoCache = (float)(sngEnd - sngStart)/(float)1000; 
 
 // Cache records in groups of 30 records. 
 pRstRoySched->MoveFirst(); 
 pRstRoySched->CacheSize = 30; 
 
 sngStart = GetTickCount(); 
 
 // Enumerate the Recordset object twice and record 
 // the elapsed time. 
 for (intLoop = 1;intLoop < 2; intLoop++) 
 { 
 pRstRoySched->MoveFirst(); 
 while(!(pRstRoySched->EndOfFile)) 
 { 
 // Execute a simple operation for the 
 // performance test. 
 strTemp = pRstRoySched->Fields-> 
 Item["title_id"]->Value; 
 pRstRoySched->MoveNext(); 
 } 
 } 
 sngEnd = GetTickCount(); 
 sngCache = (float)(sngEnd - sngStart)/(float)1000; 
 
 // Display performance results. 
 printf("Caching Performance Results:\n"); 
 printf("No cache: %6.3f seconds \n", sngNoCache); 
 printf("30-record cache: %6.3f seconds \n", sngCache); 
 } 
 catch(_com_error &e) 
 { 
 // Notify the user of errors if any. 
 _variant_t vtConnect = pRstRoySched->GetActiveConnection(); 
 
 // GetActiveConnection returns connect string if connection 
 // is not open, else returns Connection object. 
 switch(vtConnect.vt) 
 { 
 case VT_BSTR: 
 PrintComError(e); 
 break; 
 case VT_DISPATCH: 
 // Pass a connection pointer accessed from the Recordset. 
 PrintProviderError(vtConnect); 
 break; 
 default: 
 printf("Errors occured."); 
 break; 
 } 
 } 
 
 // Clean up objects before exit. 
 if (pRstRoySched) 
 if (pRstRoySched->State == adStateOpen) 
 pRstRoySched->Close(); 
} 
 
/////////////////////////////////////////////////////////// 
// // 
// PrintProviderError Function // 
// // 
/////////////////////////////////////////////////////////// 
 
void PrintProviderError(_ConnectionPtr pConnection) 
{ 
 // Print Provider Errors from Connection object. 
 
 // pErr is a record object in the Connection's Error collection. 
 ErrorPtr pErr = NULL; 
 
 if( (pConnection->Errors->Count) > 0) 
 { 
 long nCount = pConnection->Errors->Count; 
 // Collection ranges from 0 to nCount -1. 
 for(long i = 0; i < nCount; i++) 
 { 
 pErr = pConnection->Errors->GetItem(i); 
 printf("Error number: %x\t%s", pErr->Number, 
 pErr->Description); 
 } 
 } 
} 
 
/////////////////////////////////////////////////////////// 
// // 
// PrintComError Function // 
// // 
/////////////////////////////////////////////////////////// 
 
void PrintComError(_com_error &e) 
{ 
 _bstr_t bstrSource(e.Source()); 
 _bstr_t bstrDescription(e.Description()); 
 
 // Print Com errors. 
 printf("Error\n"); 
 printf("\tCode = %08lx\n", e.Error()); 
 printf("\tCode meaning = %s\n", e.ErrorMessage()); 
 printf("\tSource = %s\n", (LPCSTR) bstrSource); 
 printf("\tDescription = %s\n", (LPCSTR) bstrDescription); 
 
} 
// EndCacheSizeCpp