Many files have "changed". Which action is best?

[danaltick]

For what it's worth I'll throw in my 2 cents. My understanding is that verification is really only useful for the image data itself; especially for a raw or dng (digital negative) where the image data should never change. There are third party tools such as ImageVerifier http://basepath.com/site/detail-ImageVerifier.php designed for image verification. To my knowledge, ImageVerifier only verifies the image data not the metadata. I believe the complications/confusion is a result of attempting to verify constantly changing metadata. Hope this helps.

BTW, loving PSU

Dan

[danaltick]

One solution might be to verify the metadata and image data with separate hashes reporting if one or the other or both have changed with an option to automatically update the hash for metadata only.

[Hert]

In build 103, the signature is auto-updated.

Hert

[jstartin]

Here is a proposal that might cover some circumstances. Or I might misunderstand what is going on - I think of myself as an "averagely" perceptive and intelligent user with limited computing skills by the way.

If the user invokes autosync or write to file, from context menu or as verify action, then PSU should check the file signature against the database record before performing the action. If they agree then after the requested action the signature record should be updated - nothing has changed from outside PSU and there is no need to bother the user with "false alarms". PSU should "do its own thing" separately and automatically to detect erroneous writes from within PSU.

If the user invokes the action and PSU detects that the file has already been changed then the user should be warned of a possible problem before the requested action is performed. The user is going to have to work out why there is a difference and how to handle it. Perhaps listing a date/time for the recording of the signature in the database would be helpful here. "File changed since ddmmyyyy hhmmss".

[jstartin]

In build 103, the signature is auto-updated.
Hert

To help me get this completely clear (the technicalities here are outside my comfort-zone), am I right that:
1. A "write to file" will always calculate a new signature and update the catalogue record with it.
2. This will happen even if the file signature already differs from the catalogue record before the write.
3. "Write to file"triggered from a Verify action, explicitly from the Metadata context menu, or from autosync all have the same effect.

Thanks

[Hert]

1. A "write to file" will always calculate a new signature and update the catalogue record with it.

Yes, only if there is a pre-existing signature.

2. This will happen even if the file signature already differs from the catalogue record before the write.

Yes. That is what I mentioned in this topic as the downside of auto-updating signatures. Remember, there's no way for PSU to check the signature from *before* the write as any tool can write the file and PSU is always the mustard after... the responders thought that convenience of auto-updating was better than the small risk of storing a signature for an already changed file.

3. "Write to file"triggered from a Verify action, explicitly from the Metadata context menu, or from autosync all have the same effect.

All have the same effect.

[jstartin]

Hert
Thanks for the confirmation.

1. A "write to file" will always calculate a new signature and update the catalogue record with it.

Yes, only if there is a pre-existing signature.

So, when is there no pre-existing signature [record]. Is this not done as soon as PSU catalogues the file?

Remember, there's no way for PSU to check the signature from *before* the write as any tool can write the file and PSU is always the mustard after...

Obviously I didn't write clearly enough then ...

If PSU is required to write metadata to file wouldn't it be possible to check the signature against the catalogue before writing.
If they don't agree some other tool may have written to the file without PSU's knowledge. The user could be warned of a possible conflict and given the chance to take appropriate action.
If they do agree then the write from PSU and subsequent update of the signature record should be completely "safe".
Would this not give the best of both worlds?

[Hert]

A signature is first written when you first verify the image.

And you did write clear enough. I'm merely telling you how it works and that PSU can't check up front

Hert