Spotlight

On Mac OS X 10.4+, iNotePad notes (title and content) are indexed by Spotlight.

Thus, you can use spotlight search engine to find notes in your databases.

Content of encrypted notes (including notes in an encrypted folder or database) are of course not indexed.

If you don't want Spotlight to index the notes of a database, check the corresponding option in iNotePad preferences.

Tech. Spotlight does not directly index the notes in your database but instead uses metadata files available in ~/Library/Caches/Metadata/iNotePad/. These metadata files are generated and updated when you open a database in iNotePad. That means, until you open each of your databases in iNotePad, they won't be indexed by Spotlight.