Using DT3 Pro. I created a new db, and dragged in all the files (27,000+) from a catch-all folder I have. That catch-all folder is 9.59 GB. The database is 18.19 GB
Why?
If you are referring to the size in the Finder, the database contains more than just copies of the file. Metadata and internal metadata backups also contribute to the size.
yep, but metadata should be a very tiny fraction of the size of the data itself.
I don’t know on what basis you’d make that assessment. Metadata, especially text metadata is not inconsequential.
A screen capture of File > Database Properties for the database could be helpful.
Must have been a one-off. I trimmed out by hand in the source folder, taking it to 5.13 GB. Then created a new db, and imported again. The imported size is 5.15 (not more than double the size.)
(On what basis would I say metadata should not double the size of the database? Well, how’s 42 years as a professional programmer to start? 
And the empirical results (above) of doing the import over again seems to confirm it as well.
Thanks for your time, however. Your courtesy in responding is appreciated. Happy Holidays!
Happy holidays to you and yours as well.
PS: I wouldn’t say the size would have doubled necessarily _(hence the questions ), but (non-programmer) people don’t realize that the metadata and full text of documents takes up more space than they imagine it would. Cheers!