Using facets to debug search differences for large files

I was using Millennium's Create List search, but then I needed to tweak it a bit. The problem I had is that the file was rather huge (15K worth of records) and it was going to be a bear to figure out which records had fallen out of the old search and which new records had been picked up.

Usually, I would dump both lists of record numbers into Excel, highlight the duplicate values, and scroll through, but that wasn't feasible for quickly checking 15K records.

Instead, I was able to use Open Refine's faceting ability to help me filter through the data. I dumped the record numbers from the old search into one column in Excel (labeled "Column 1"), dumped the record numbers from the new search into a second column (labeled "Column 2"), saved, and then sent the sheet over to Open Refine.

I hit the drop down menu on any column and chose Facet->Custom Text Facet.

Then I entered this GREL:

cells["Column 1"].value == cells["Column 2"].value

Then I clicked on "false" in the facet to see what wasn't matching. Note that you have to use the object cells and not cell. I should also note that this expression isn't too useful if the two columns are wildly out of sync. It's mostly useful for needle in a haystack situations.