iOS應用程序的脫機緩存sqlite3變得損壞

Question

我有一個用於iOs應用程序的sqlite3數據庫，以便爲系統提供脫機支持。

它完美的作品。但有時.db文件損壞。並不返回結果。

如果我檢查SELECT指令throught在命令行中，我得到一個錯誤信息：

sqllite Error: database disk image is malformed 

雖然是不可取的它被損壞。數據庫只是一個輔助系統，足以能夠從iOS應用程序檢測到文件已損壞並重新啓動文件。

但使用sqlite3語句我沒有得到任何異常。代碼如下所示：

sqlRaw = @"SELECT ... "; 
const char *sql = [sqlRaw cStringUsingEncoding:NSUTF8StringEncoding]; 
if (sqlite3_prepare_v2(database, sql, -1, &date_statement, NULL) != SQLITE_OK) { 
    NSAssert1(0, @"Error: failed to prepare statement with message '%s'.", sqlite3_errmsg(database)); 
} 

NSMutableArray *entities = [[NSMutableArray alloc] initWithCapacity:0]; 
while (sqlite3_step(date_statement) == SQLITE_ROW) { 
    NSData *entityXml = [[NSData alloc] initWithBytes:sqlite3_column_blob(date_statement, 0) 
                length:sqlite3_column_bytes(date_statement, 0)]; 
    [entities addObject:entityXml]; 
} 
sqlite3_finalize(date_statement); 

當應用程序執行前面的代碼時，只需返回一個空數組，不會引發異常。

任何人都知道如何從sqlite3語句檢查.db文件狀態？

也許對用戶其他存儲系統更好。任何建議？

Answer 1

最後我決定從應用程序中檢查數據庫狀態，並且如果數據庫已經損壞，只需替換一個新的空數據庫。

- (BOOL) isDatabaseCorrupted { 
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; 
    NSString *path = [documentsDirectory stringByAppendingPathComponent:cache_final_path]; 
    BOOL bResult = FALSE; 
    if (sqlite3_open([path UTF8String], &database) == SQLITE_OK) { 
     @try { 
      NSString *sqlRaw = @"PRAGMA integrity_check;"; 
      const char *sql = [sqlRaw cStringUsingEncoding:NSUTF8StringEncoding]; 
      if (sqlite3_prepare_v2(database, sql, -1, &check_statement, NULL) == SQLITE_OK) { 
       int success = sqlite3_step(check_statement); 
       NSLog(@"SQL integrity_check result is %d", success); 
       NSString *response = nil; 
       switch (success) { 
        case SQLITE_ERROR: 
         bResult = TRUE; 
         break; 
        case SQLITE_DONE: 
         NSLog(@"Result is simple DONE of the sqllite3 on isDatabaseCorrupted"); 
         break; 
        case SQLITE_BUSY: 
         NSLog(@"Result is simple BUSY of the sqllite3 on isDatabaseCorrupted"); 
         break; 
        case SQLITE_MISUSE: 
         NSLog(@"Bad utilization of the sqllite3 on isDatabaseCorrupted"); 
         break; 
        case SQLITE_ROW: 
         response = [NSString stringWithUTF8String:(char *)sqlite3_column_text(check_statement, 0)]; 
         if ([[[response lowercaseString] stringByTrimmingCharactersInSet:[NSCharacterSet 
                          whitespaceAndNewlineCharacterSet]] 
          isEqualToString:@"ok"]){ 
          bResult = FALSE; 
         } else { 
          NSLog(@"ATTENTION: integrity_check response %@", response); 
          bResult = TRUE; 
         } 
         break; 
        default: 
         break; 
       } 

       sqlite3_finalize(check_statement); 
      } 

     } 
     @catch (NSException *exception) { 
      [TSLogger log:[NSString stringWithFormat:@"Exception %@", [exception description]] 
      withSeverity:severity_error]; 
      return TRUE; 
     }   
    } 

    sqlite3_close(database); 
    return bResult; 
} 

結果按照sqlite3文檔的預期響應順序定義。

謝謝

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