How to compact local landmark databases

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Article

Created: Den123 (10 Apr 2008)

Last edited: hamishwillee (26 Jul 2012)

All local landmark databases are stored in files. As a result of some data changes ( for example: the addition of new landmarks ), it could happens that the size of database files will be greater then the necessary minimum.

The following code snippet demonstrates how to compress all local databases and calculate the count of the released bytes.

Headers Required:

#include <epos_cposlmdatabasemanager.h>
#include <epos_cposlandmarkdatabase.h>
#include <aknnotewrappers.h>  //for the information note

Link against:

LIBRARY eposlmdbmanlib.lib'' 
LIBRARY eposlandmarks.lib'' 
LIBRARY avkon.lib eikcdlg.lib eikctl.lib //for the information note

Source:

// db manager
CPosLmDatabaseManager* dbManager = CPosLmDatabaseManager :: NewL();
CleanupStack :: PushL( dbManager );
 
// protocol for the local DB
_LIT( KFileProto, "file" );
 
// array, that contains URI of the local DBs	
CDesCArray* dbUriList = dbManager->ListDatabasesLC( KFileProto );		   
 
TInt delta = 0;	// delta of the total size
for(TInt i = 0; i < dbUriList->Count(); i++ )
{
   // open database
   CPosLandmarkDatabase* db = CPosLandmarkDatabase :: OpenL( (*dbUriList)[i] );
   CleanupStack :: PushL( db );
 
   // initialize if necessary
   if( db->IsInitializingNeeded() )
   ExecuteAndDeleteLD( db->InitializeL() );	   
 
   // get size before compact
   CPosLandmarkDatabase :: TSize oldSize = db->SizeL();
 
   // execute compact in batch mode
   ExecuteAndDeleteLD( db->CompactL() );
 
   // get size after compact
   CPosLandmarkDatabase :: TSize newSize = db->SizeL();
 
   // inc delta
   delta += oldSize.iFileSize - newSize.iFileSize;
   CleanupStack :: PopAndDestroy(); // db
}		               
CleanupStack :: PopAndDestroy( 2 ); // iDbList dbManager	
 
// create message
_LIT( KMess, "Released bytes: " );
TBuf<32> mess( KMess );
mess.AppendNum( delta );
 
// show message
CAknInformationNote* informationNote;
informationNote = new ( ELeave ) CAknInformationNote;
informationNote->ExecuteLD( mess );

Related Links:

• Landmarks/web client example using Carbide.c++ and UI designer
• How to use Landmarks API
• How to select and show a landmark
• How to export landmarks from database to file
• How to import landmarks from file to database
• Execution of landmark operations
• How to obtain and save current location
• Retrieving location information
• How to manage landmark categories