Is there anything I have to be careful before I use the data migration tool?

Hi, I am wondering is there anything I have to take care of before I use the data migration tool to migrate my data to a new copy?

There are a few things. For example, field deletions in combination with field renames can cause issues. I recommend you read the documentation because there are a few gotchas.


Make sure that you are using the appropriate version of DMT.


Edit: my previous posting wasn't a good comparison so I removed it. :slight_smile:

Check the field index of relevant fields. Was a bug that these can get messed up after migration.

none of the APIs can do custom value lists and accounts to name just two... so: not quite the same thing.


make sure to have the DMT pipe its output to a text file so that you can inspect the resulting log file.


That's cool.

For me the Data API is a no-go so I'll always suggest something as close as possible and leave it to the OP to determine if a workaround makes sense.

For me: Non-proprietary when possible, and non-"metered" ... always.


The DMT is not API related. Not using the DMT, and instead trying to replicate it with the APIs will leave out significant portions of the file.

While I agree that often having multiple options is a good thing, this is an area where suggesting other methods can cause severe and irreparable omissions from the file.

DMT works at the file block level, and can do things you simply can't any other way. The gotchas are very, very few and affect only a small segment of the developer/user population.


Sorry, no (for me).

Fully disagree. Have you used the DMT?

Thank you. Could you please briefly explain how to create a log file?

I'm not following; what are you saying no to?
Your insistence on non-proprietary tools is noted but totally irrelevant here. The DMT is a command line utility to push data and some parts of the schema between two versions of the same FM file.

It has nothing to do with any APIs or having to pay to play. It can be used with any file in the .fmp12 file format, so going back as far as FM12.


It depends a little on whether you use macOS or Windows.

On windows you basically append this to the end of the DMT command: ">c:\DMT.txt"
This will the command not display its progress in the command line console but write it all out to that path you specified.
If you want to have both then the command is a little more involved.

macOS has similar functionality.

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I would just do the data transfer a different way, that's all I was saying. :slight_smile:

(No FDS required, for one thing.)

Import, JDBC, Data API, or any other form of transferring the data can take hours for any decent amount of data. In the case of our files, it actually would take 36 hours.

With the DMT, it is 40 mins. Using a tool like Otto ( which has the DMT bundled ), it's automated and I don't have to sit there. I schedule it, and walk away. If you only have a gigabyte of data, it's seconds. This allows a completely different development/deployment flow that doesn't rely on freeing up hours and hours of time to do a migration.

Also, as you see in the Preview webinar, they are making both the iOS SDK and the DMT available to the general population. So it will not require the FDS subscription. It will be a part of the platform that you get.

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I don't know where you get your JDBC benchmarks, but JDBC from my testing is three times faster than FileMaker itself (benchmarks posted over and over). However, since I've already written a generic data importer that works with multiple database (I just point it, start it, and forget it), I just stick with that and with industry standards.

With MySQL, Oracle, SQL Server, and others, there are automated sync and data transfer utilities built right into the data tool I use so I mostly just use that tool for those.

I'm sure the DMT is fine; I just don't need it. :slight_smile:

Thanks J.

Maybe the difference here is that we can't have that much downtime.

Hard to imagine because there is no other tool that can transfer things like accounts and custom value list. If you avoid the DMT because of some dogmatic principle then you are are not giving your clients the full possible experience of easy friction-less data migrations.


It's good to know there's a tool like DMT if I ever need it. So far, nope.