iOS应用程序sqlite3上的脱机缓存已损坏

Question

我有一个iOs应用程序的sqlite3数据库,以便为系统提供离线支持.

它完美地运作.但有时.db文件已损坏.而且不会返回结果.

如果我通过命令行检查SELECT指令,我会收到下一条错误消息:

sqllite Error: database disk image is malformed

虽然不可取,但它会变得腐败.数据库只是一个辅助系统,足以能够从iOS应用程序检测到文件已损坏并重新启动文件.

但是使用sqlite3语句我没有得到任何异常.代码如下:

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);

当应用程序执行前面的代码时,只返回一个空数组,不会抛出任何异常.

有谁知道如何从sqlite3语句检查.db文件状态？

也许用户其他存储系统更好.有什么建议？

Answer 1

最后,我决定从应用程序检查数据库状态,如果数据库已损坏,则只需替换新的空数据库.

- (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;
}

结果是按照sqlite3文档的预期响应顺序定义的.

谢谢,

伊万