What is the best storage method for an Evernote-like app?

Question

Evernote

Hello.
You must select how information is stored for the Evernote-like application.
Those. there will be text notes with attachments (images, files), metainformation (tags, folders, etc.).
The application will be cross-platform. The data structure must also be cross-platform, i.e. is the same for Mac and Windows clients. Most likely electron or nw.js will be used. There can be any number of notes. It needs to be done quickly. In principle, the speed of Evernote suits. All information is, of course, local. How to store notes? File system, SQL, noSQL, elasticsearch? Is it possible to just put each note in a csv in a folder, store it in a database? How to store images attached files?

Answer 1

I'll try to briefly explain:
1. Any document has a structure (markup).
2. Any structure has data types (they are also blocks).
3. Any type of data has its own format, purpose and volume.
Storage:
1. All "heavy" data types (multimedia/applications, archives/documents) are stored in a file structure on disk.
2. All "light" types (document markup and text data: document "body", notes, review, glossary, footnotes, translations) are stored in the database.
The structure of the database and the database itself - depends on the tasks and can be any (mysql - more than enough).