notesmachine/server/nm-store/docs/storage.md

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Storage layer for Notesmachine

This library implements the core functionality of Notesmachine and describes that functionality to a storage layer. There's a bit of intermingling in here which can't be helped, although it may make sense in the future to separate the decomposition of the note content into a higher layer.

Notesmachine storage notes consist of two items: Zettle and Kasten, which are German for "Note" and "Box". Here are the basic rules:

  • Boxes have titles (and date metadata)
  • Notes have content and a type (and date metadata)
  • Notes are stored in boxes
    • Notes are positioned with respect to other notes.
    • There are two positions:
      • Siblings, creating lists
      • Children, creating trees like this one
  • Notes may have references (pointers) to other boxes
  • Notes may be moved around
  • Notes may be deleted
  • Boxes may be deleted
  • When a box is renamed, every reference to that box is auto-edited to reflect the change. If a box is renamed to match an existing box, the notes in both boxes are merged.

Note-to-note relationships form trees, and are kept in a SQL database of (parent_id, child_id, position, relationship_type). The position is a monotonic index on the parent (that is, every pair (parent_id, position) must be unique). The relationship_type is an enum and can specify that the relationship is original, embedding, or referencing. An embedded or referenced note may be read/write or read-only with respect to the original, but there is only one original note at any time.

Note-to-box relationships form a graph, and are kept in the SQL database as a collection of edges from the note to the box (and naturally vice-versa).

  • Decision: When an original note is deleted, do all references and embeddings also get deleted, or is the oldest one elevated to be a new "original"? Or is that something the user may choose?

  • Decision: Should the merging issue be handled at this layer, or would it make sense to move this to a higher layer, and only provide the hooks for it here?