-- Many-to-many join table between thoughts and learnings.
-- Allows a learning to reference multiple source thoughts and a thought to
-- expose multiple related learnings, queryable in both directions.

CREATE SEQUENCE IF NOT EXISTS public.identity_thought_learning_links_id
  INCREMENT 1
  MINVALUE 1
  MAXVALUE 9223372036854775807
  START 1
  CACHE 1;

CREATE TABLE IF NOT EXISTS public.thought_learning_links (
  id bigint NOT NULL DEFAULT nextval('public.identity_thought_learning_links_id'),
  thought_id bigint NOT NULL REFERENCES public.thoughts(id) ON DELETE CASCADE,
  learning_id bigint NOT NULL REFERENCES public.learnings(id) ON DELETE CASCADE,
  relation text NOT NULL DEFAULT 'source',
  created_at timestamptz NOT NULL DEFAULT now(),
  CONSTRAINT thought_learning_links_pkey PRIMARY KEY (id),
  CONSTRAINT thought_learning_links_unique UNIQUE (thought_id, learning_id)
);

CREATE INDEX IF NOT EXISTS idx_thought_learning_links_thought_id
  ON public.thought_learning_links (thought_id);

CREATE INDEX IF NOT EXISTS idx_thought_learning_links_learning_id
  ON public.thought_learning_links (learning_id);