JSON Entity Storage

JSON Entity Storage is an alternative backend for Drupal content entities. It stores field values in JSON documents while preserving the SQL layout Drupal expects for entity queries: generated columns expose single-value fields, and SQL views expose multi-value fields.

Key features

• The storage reads all of an entity's field values in one query and writes them in one query per shared table, regardless of how many single-value or multi-value fields it has.
• Pending revisions can hold incomplete data. The storage enforces required fields only when it saves a published default revision.
• A field can change cardinality without moving its stored values. The new limit simply cannot discard existing values.
• New field storages share the entity's existing data tables, which is especially useful when staging field changes in a workspace.

This is experimental work that also serves as a proving ground for new core database APIs. It requires these core changes:

• #3343634: JSON support in the database API.
• #3586688: Generated columns in the schema API.
• #3618770: SQL views in the schema API.