CHIA-1436: Revert "CHIA-645 Optimize build ancestors table. (#18100)"

chia/data_layer/data_store.py

@@ -1737,41 +1737,32 @@ async def _get_one_ancestor_multiple_hashes(
             return [InternalNode.from_row(row=row) for row in rows]
 
     async def build_ancestor_table_for_latest_root(self, store_id: bytes32) -> None:
-        async with self.db_wrapper.writer() as writer:
+        async with self.db_wrapper.writer():
             root = await self.get_tree_root(store_id=store_id)
             if root.node_hash is None:
                 return
+            previous_root = await self.get_tree_root(
+                store_id=store_id,
+                generation=max(root.generation - 1, 0),
+            )
 
-            await writer.execute(
-                """
-                WITH RECURSIVE tree_from_root_hash AS (
-                    SELECT
-                        node.hash,
-                        node.left,
-                        node.right,
-                        NULL AS ancestor
-                    FROM node
-                    WHERE node.hash = :root_hash
-                    UNION ALL
-                    SELECT
-                        node.hash,
-                        node.left,
-                        node.right,
-                        tree_from_root_hash.hash AS ancestor
-                    FROM node
-                    JOIN tree_from_root_hash ON node.hash = tree_from_root_hash.left
-                    OR node.hash = tree_from_root_hash.right
+            if previous_root.node_hash is not None:
+                previous_internal_nodes: List[InternalNode] = await self.get_internal_nodes(
+                    store_id=store_id,
+                    root_hash=previous_root.node_hash,
                 )
-                INSERT OR REPLACE INTO ancestors (hash, ancestor, tree_id, generation)
-                SELECT
-                    tree_from_root_hash.hash,
-                    tree_from_root_hash.ancestor,
-                    :tree_id,
-                    :generation
-                FROM tree_from_root_hash
-                """,
-                {"root_hash": root.node_hash, "tree_id": store_id, "generation": root.generation},
+                known_hashes: Set[bytes32] = {node.hash for node in previous_internal_nodes}
+            else:
+                known_hashes = set()
+            internal_nodes: List[InternalNode] = await self.get_internal_nodes(
+                store_id=store_id,
+                root_hash=root.node_hash,
             )
+            for node in internal_nodes:
+                # We already have the same values in ancestor tables, if we have the same internal node.
+                # Don't reinsert it so we can save DB space.
+                if node.hash not in known_hashes:
+                    await self._insert_ancestor_table(node.left_hash, node.right_hash, store_id, root.generation)
 
     async def insert_root_with_ancestor_table(
         self, store_id: bytes32, node_hash: Optional[bytes32], status: Status = Status.PENDING