Running your source code reveals that StopAllProcess() is called multiple times, but Command?.Cancel() throws a null reference exception.

[LISALASUGER]

StopAllProcess()

Running your source code reveals that StopAllProcess() is called multiple times, but Command?.Cancel() throws a null reference exception.

fix advice：
public void StopAllProcess()
{
stopProcess = true;
if (Command != null)
{
try
{
Command.Cancel();
}
catch
{
// Ignore any errors in cleanup
}
}
timerReport?.Stop();

[LISALASUGER]

Another issue is that during the backup and restore process, this library can be interfered with by Navicat's refresh operation, resulting in incomplete restoration.

[LISALASUGER]

I'd like to know the maximum size of the SQL file your database supports for backup and restore,thank you very much.

[adriancs2]

Hi, thanks for the report. I'll try to have a look into it. Regarding your question about the max size this library can support. The library itself does not impose any limitation. If there is any limitation, it will be from the MySQL server that it is connecting with. Or there are other hidden limitation of the software environment that you are running, such as web request time-out, software UI timeout. But if you run this in a background thread/task, it will run on another thread which is not on the main UI thread, this will unlock the timeout issues. But anyway, even with running on 32bit process, the library processes things by chunk, so it should be ok to process any length of database size.

[LISALASUGER]

I hope your library gets better and better, more complete and stronger. Best wishes, buddy!

[adriancs2]

I have already improved the StopAllProcess() method. It can be called multiple times which is ok and it is designed to be idiomatic.

New version v2.7 is released. Thank you buddy.

Below is the improved code:

// Override StopAllProcess to handle parallel processing
public void StopAllProcess()
{
    stopProcess = true;
    try { Command?.Cancel(); } catch { }
    try { timerReport?.Stop(); } catch { }

    try
    {
        if (_rowDataCollection != null && !_rowDataCollection.IsAddingCompleted)
            _rowDataCollection.CompleteAdding();
    }
    catch { }

    try
    {
        if (_sqlStatementCollection != null && !_sqlStatementCollection.IsAddingCompleted)
            _sqlStatementCollection.CompleteAdding();
    }
    catch { }

    try
    {
        if (_importQueryCollection != null && !_importQueryCollection.IsAddingCompleted)
            _importQueryCollection.CompleteAdding();
    }
    catch { }
}

// Override Dispose to handle parallel processing cleanup
public void Dispose()
{
    try { StopAllProcess(); } catch { }

    // Wait for tasks to complete with timeout
    try
    {
        var tasks = new List<Task>();
        if (_phase1Task != null) tasks.Add(_phase1Task);
        if (_phase2Task != null) tasks.Add(_phase2Task);
        if (_phase3Task != null) tasks.Add(_phase3Task);
        if (_importPhase1Task != null) tasks.Add(_importPhase1Task);
        if (_importPhase2Task != null) tasks.Add(_importPhase2Task);
        if (tasks.Count > 0)
            Task.WaitAll(tasks.ToArray(), TimeSpan.FromSeconds(10));
    }
    catch { }

    try { _rowDataCollection?.Dispose(); } catch { }
    try { _sqlStatementCollection?.Dispose(); } catch { }
    try { _importQueryCollection?.Dispose(); } catch { }

    try { timerReport?.Stop(); } catch { }
    try { timerReport?.Dispose(); timerReport = null; } catch { }

    try { textWriter?.Dispose(); textWriter = null; } catch { }
    try { textReader?.Dispose(); textReader = null; } catch { }
}

[adriancs2]

About the other issue of Navicat's refresh operation...

This is a MySQL connection/session issue, not a library bug. The problem is that Navicat (a MySQL GUI client) periodically runs queries like SHOW TABLES, SELECT COUNT(*), or schema refreshes on the same database, which can interfere with the backup/restore operations — particularly with table locks, transactions, or auto-increment values.

Here are some of the strategies that you can try:

Method 1: For Restore: restore into a new database

Put your main application in maintenance mode or read only mode.
assume that your application is using mydb1, the connection string will look something like this:

server=localhost;user=myuser;pwd=1234;database=mydb1;

Restore the backup to new database mydb_new2, then update your main application's connection to the new db:

server=localhost;user=myuser;pwd=1234;database=mydb_new2;

Resume the application for production.

Method 2: For Backup: use a replica

Implement a master-replica strategy. Before you want to perform a backup. Stop the replication process:

STOP REPLICA;    -- pause replication (MySQL 8.0.22+)
-- perform backup --
START REPLICA;   -- resume replication

Run the backup process targeting the replica. With this you can perform the backup process without the need to take down the main application.

A few other alternative solutions you can try:

• Close Navicat (or any other GUI client) during backup/restore
• Disable Navicat's auto-refresh feature while the operation runs
• Use a dedicated MySQL connection/user for backup that isn't shared with Navicat
• Enable table locking during export/import to prevent interference:
  mb.ExportInfo.EnableLockTablesWrite = true;

[adriancs2]

I republished the backup and restore strategy as a wiki page to share the info:
https://github.com/MySqlBackupNET/MySqlBackup.Net/wiki/Strategy-%E2%80%90-Backup-and-Restore-Large-Database-On-a-Production-Server