Comparing 15,000 files in two local directories

I have a situation where SharePoint cloud did not synch completely with local synched copy of it. Result was two different local SharePoint folders. Same number of subfolders, about 28,000 but one has 10,000 files vs 25,000 total files in the other one.

I modified and added about 50 files since the incomplete duplicate was created. The new files are stored in the incomplete one. But I'm not sure which files they were.

Is there a way to compare files so i can just find the ones with a date/time stamp post say 4 10 20 10pm ? if you have another suggestion, I'm open to any ideas

The Find tool should be able to handle this

The Synchronize tool can help merge the two different local SharePoint folders.

before merging, would i first add the root folders of the two directories to the "find in" box?

From what you've written I'd say you can solve your problem by doing a one-way sync with the incomplete copy as source and the complete copy as destination, keeping the newer files in case of a conflict.

Before i synch, would it show me which files from the newer incomplete folders were going to which older (but more complete except for the newer files) folders?

And let me decide which ones to copy over?

What preference do i need to have set so that a copy number etc. is added to the file number if same file name already exists on the target?

You can use the Copy command or the Synchronize tool. They are similar but not equal. Copy can rename files with identical names, Synchronize will show you what it will copy before you commit.

Have a look at the docs to see what's best for you.!Documents/Copy.htm!Documents/Synchronize.htm

How does synchronize and Copy deal with files that are using MS "download on demand"?
I just realized that one of the two sets of locally synched files, one actually has many of them downloaded to the local drive while the other set has most of them in the cloud. The latter is the one that i want to copy or synch some of the newer files from the other set of folders to.

So if the comparison is just date, time, size attributes then I'd think I'd be good. But if they compare in cloud vs stored locally, for example, I'd get a zillion false differences.

They don't compare contents (only the duplicate finder does that).

(It'd usually take the same amount of time to just overwrite the files without checking, if the whole files have to be read and compared.)

You may find that something triggers offline files to be downloaded though (e.g. if certain file display columns are turned on), so I would be careful of that.

With a huge number of files, using Copy is fine. Using the interactive Sync tool may not work that well as it can get very slow with that many files (depending on the exact situation). (That's something we might improve in the future, of course. And you may find it's already OK for your use-case, depending on the exact details.)

If you want an interactive sync with a large number of files/folders, where you need to see what's going to happen and modify what will happen for individual files and folders before committing the change, a dedicated diff/merge tool might be worth looking at. I use and like Beyond Compare personally, but there are also free tools like WinMerge which are pretty good too. They can be tightly integrated into Opus so you just push a button to launch them against the left and right folder:

I'm following your advice on Beyond Compare and integration now. Thanks again.