java - Java derby 数据库上的数据库备份

Question

我正在使用 java anad derby 数据库编写客户跟踪程序。 我需要备份此数据库并在必要时将其安装回去。

如何做到这一点？

Answer 1

根据 Derby

离线备份

To perform an offline backup of a database, use operating system commands to copy the database directory. You must shut down the database prior to performing an offline backup.

For example, on Windows systems, the following operating system command backs up a (closed) database that is named sample and that is located in d:\mydatabases by copying it to the directory c:\mybackups\2005-06-01:

xcopy d:\mydatabases\sample c:\mybackups\2005-06-01\sample /s /i

If you are not using Windows, substitute the appropriate operating system command for copying a directory and all contents to a new location.

在线备份

Use online backups to back up a database while it is running. You can perform online backups by using several types of backup procedures or by using operating systems commands with the freeze and unfreeze system procedures. Using the backup procedure to perform an online backup:

Use the SYSCS_UTIL.SYSCS_BACKUP_DATABASE procedure to perform an online backup of a database to a specified location. The SYSCS_UTIL.SYSCS_BACKUP_DATABASE procedure takes a string argument that represents the location in which to back up the database. Typically, you provide the full path to the backup directory. (Relative paths are interpreted as relative to the current directory, not to the derby.system.home directory.)

For example, to specify a backup location of c:/mybackups/2005-06-01 for a database that is currently open, use the following statement (forward slashes are used as path separators in SQL commands):

CALL SYSCS_UTIL.SYSCS_BACKUP_DATABASE('c:/mybackups/2005-06-01')

The SYSCS_UTIL.SYSCS_BACKUP_DATABASE() procedure puts the database into a state in which it can be safely copied, then copies the entire original database directory (including data files, online transaction log files, and jar files) to the specified backup directory. Files that are not within the original database directory (for example, derby.properties) are not copied.

The following example shows how to back up a database to a directory with a name that reflects the current date:

public static void backUpDatabase(Connection conn)throws SQLException
{
    // Get today's date as a string:
    java.text.SimpleDateFormat todaysDate = 
        new java.text.SimpleDateFormat("yyyy-MM-dd");
    String backupdirectory = "c:/mybacksup/" + todaysDate.format((java.util.Calendar.getInstance()).getTime());

    CallableStatement cs = conn.prepareCall("CALL SYSCS_UTIL.SYSCS_BACKUP_DATABASE(?)"); 
    cs.setString(1, backupdirectory);
    cs.execute(); 
    cs.close();
    System.out.println("backed up database to "+backupdirectory);
}

For a database that was backed up on 2005-06-01, the previous commands copy the current database to a directory of the same name in c:/mybackups/2005-06-01. Uncommitted transactions do not appear in the backed-up database.

Note: Do not back up different databases with the same name to the same backup directory. If a database of the same name already exists in the backup directory, it is assumed to be an older version and is overwritten.

The SYSCS_UTIL.SYSCS_BACKUP_DATABASE procedure will issue an error if there are any unlogged operations in the same transaction as the backup procedure. If any unlogged operations are in progress in other transactions in the system when the backup starts, this procedure will block until those transactions are complete before performing the backup. Derby automatically converts unlogged operations to logged mode if they are started while the backup is in progress (except operations that maintain application jar files in the database). Procedures to install, replace, and remove jar files in a database are blocked while the backup is in progress.

If you do not want backup to block until unlogged operations in other transactions are complete, use the SYSCS_UTIL.SYSCS_BACKUP_DATABASE_NOWAIT procedure. This procedure issues an error immediately at the