PRUNE_HEADS_SQL = f"\nSELECT\n h.checkpoint_ns,\n h.checkpoint_id AS head,\n CASE WHEN (
c.checkpoint ->> 'v')::int < 4 AND EXISTS (\n SELECT 1 FROM checkpoint_writes w\n WHERE w.thread_id = %s\n AND w.checkpoint_ns = h.checkpoint_ns\n AND w.checkpoint_id = c.parent_checkpoint_id\n AND w.channel = '{TASKS}'\n ) THEN c.parent_checkpoint_id END AS sends_parent,\n c.metadata -> 'parents' ->> '' AS root,\n EXISTS (\n SELECT 1 FROM checkpoints r\n WHERE r.thread_id = %s AND r.checkpoint_ns = ''\n AND r.checkpoint_id = c.metadata -> 'parents' ->> ''\n ) AS root_saved\nFROM (\n SELECT DISTINCT ON (checkpoint_ns) checkpoint_ns, checkpoint_id\n FROM checkpoints\n WHERE thread_id = %s\n ORDER BY checkpoint_ns DESC, checkpoint_id DESC\n) AS h\nCROSS JOIN LATERAL (\n SELECT checkpoint, parent_checkpoint_id, metadata FROM checkpoints\n WHERE thread_id = %s\n AND checkpoint_ns = h.checkpoint_ns\n AND checkpoint_id = h.checkpoint_id\n
) AS c\n"
