There is only one file type that uses the .LRDATA extension:
Adobe Lightroom Data File
Data file used by Adobe Lightroom, a program used to organize and edit digital photos; contains image preview data supporting a Lightroom digital photo catalog (.LRCAT file); includes image metadata which enables users to browse through digital photo information.
NOTE: Lightroom was formerly known as Photoshop Lightroom.
Updated: August 16, 2017