graph/db+sqldb: use batch validation for node migration

diff --git a/graph/db/sql_migration.go b/graph/db/sql_migration.go
index 9b22fbf..72947bd 100644
--- a/graph/db/sql_migration.go
+++ b/graph/db/sql_migration.go
@@ -107,8 +107,8 @@ func checkGraphExists(db kvdb.Backend) (bool, error) {
 }
 
 // migrateNodes migrates all nodes from the KV backend to the SQL database.
-// This includes doing a sanity check after each migration to ensure that the
-// migrated node matches the original node.
+// It collects nodes in batches, inserts them individually, and then validates
+// them in batches.
 func migrateNodes(ctx context.Context, cfg *sqldb.QueryConfig,
 	kvBackend kvdb.Backend, sqlDB SQLQueries) error {
 
@@ -125,6 +125,108 @@ func migrateNodes(ctx context.Context, cfg *sqldb.QueryConfig,
 		}
 	)
 
+	// batch is a map that holds node objects that have been migrated to
+	// the native SQL store that have yet to be validated. The object's held
+	// by this map were derived from the KVDB store and so when they are
+	// validated, the map index (the SQL store node ID) will be used to
+	// fetch the corresponding node object in the SQL store, and it will
+	// then be compared against the original KVDB node object.
+	batch := make(
+		map[int64]*models.LightningNode, cfg.MaxBatchSize,
+	)
+
+	// validateBatch validates that the batch of nodes in the 'batch' map
+	// have been migrated successfully.
+	validateBatch := func() error {
+		if len(batch) == 0 {
+			return nil
+		}
+
+		// Extract DB node IDs.
+		dbIDs := make([]int64, 0, len(batch))
+		for dbID := range batch {
+			dbIDs = append(dbIDs, dbID)
+		}
+
+		// Batch fetch all nodes from the database.
+		dbNodes, err := sqlDB.GetNodesByIDs(ctx, dbIDs)
+		if err != nil {
+			return fmt.Errorf("could not batch fetch nodes: %w",
+				err)
+		}
+
+		// Make sure that the number of nodes fetched matches the number
+		// of nodes in the batch.
+		if len(dbNodes) != len(batch) {
+			return fmt.Errorf("expected to fetch %d nodes, "+
+				"but got %d", len(batch), len(dbNodes))
+		}
+
+		// Now, batch fetch the normalised data for all the nodes in
+		// the batch.
+		batchData, err := batchLoadNodeData(ctx, cfg, sqlDB, dbIDs)
+		if err != nil {
+			return fmt.Errorf("unable to batch load node data: %w",
+				err)
+		}
+
+		for _, dbNode := range dbNodes {
+			// Get the KVDB node info from the batch map.
+			node, ok := batch[dbNode.ID]
+			if !ok {
+				return fmt.Errorf("node with ID %d not found "+
+					"in batch", dbNode.ID)
+			}
+
+			// Build the migrated node from the DB node and the
+			// batch node data.
+			migNode, err := buildNodeWithBatchData(
+				dbNode, batchData,
+			)
+			if err != nil {
+				return fmt.Errorf("could not build migrated "+
+					"node from dbNode(db id: %d, node "+
+					"pub: %x): %w", dbNode.ID,
+					node.PubKeyBytes, err)
+			}
+
+			// Make sure that the node addresses are sorted before
+			// comparing them to ensure that the order of addresses
+			// does not affect the comparison.
+			slices.SortFunc(
+				node.Addresses, func(i, j net.Addr) int {
+					return cmp.Compare(
+						i.String(), j.String(),
+					)
+				},
+			)
+			slices.SortFunc(
+				migNode.Addresses, func(i, j net.Addr) int {
+					return cmp.Compare(
+						i.String(), j.String(),
+					)
+				},
+			)
+
+			err = sqldb.CompareRecords(
+				node, migNode,
+				fmt.Sprintf("node %x", node.PubKeyBytes),
+			)
+			if err != nil {
+				return fmt.Errorf("node mismatch after "+
+					"migration for node %x: %w",
+					node.PubKeyBytes, err)
+			}
+		}
+
+		// Clear the batch map for the next iteration.
+		batch = make(
+			map[int64]*models.LightningNode, cfg.MaxBatchSize,
+		)
+
+		return nil
+	}
+
 	// Loop through each node in the KV store and insert it into the SQL
 	// database.
 	err := forEachNode(kvBackend, func(_ kvdb.RTx,
@@ -172,52 +274,16 @@ func migrateNodes(ctx context.Context, cfg *sqldb.QueryConfig,
 				err)
 		}
 
-		// Fetch it from the SQL store and compare it against the
-		// original node object to ensure the migration was successful.
-		dbNode, err := sqlDB.GetNodeByPubKey(
-			ctx, sqlc.GetNodeByPubKeyParams{
-				PubKey:  node.PubKeyBytes[:],
-				Version: int16(ProtocolV1),
-			},
-		)
-		if err != nil {
-			return fmt.Errorf("could not get node by pubkey (%x)"+
-				"after migration: %w", pub, err)
-		}
-
-		// Sanity check: ensure the migrated node ID matches the one we
-		// just inserted.
-		if dbNode.ID != id {
-			return fmt.Errorf("node ID mismatch for node (%x) "+
-				"after migration: expected %d, got %d",
-				pub, id, dbNode.ID)
-		}
-
-		migratedNode, err := buildNode(ctx, cfg, sqlDB, dbNode)
-		if err != nil {
-			return fmt.Errorf("could not build migrated node "+
-				"from dbNode(db id: %d, node pub: %x): %w",
-				dbNode.ID, pub, err)
-		}
+		// Add to validation batch.
+		batch[id] = node
 
-		// Make sure that the node addresses are sorted before
-		// comparing them to ensure that the order of addresses does
-		// not affect the comparison.
-		slices.SortFunc(node.Addresses, func(i, j net.Addr) int {
-			return cmp.Compare(i.String(), j.String())
-		})
-		slices.SortFunc(
-			migratedNode.Addresses, func(i, j net.Addr) int {
-				return cmp.Compare(i.String(), j.String())
-			},
-		)
-
-		err = sqldb.CompareRecords(
-			node, migratedNode, fmt.Sprintf("node %x", pub),
-		)
-		if err != nil {
-			return fmt.Errorf("node mismatch after migration "+
-				"for node %x: %w", pub, err)
+		// Validate batch when full.
+		if len(batch) >= cfg.MaxBatchSize {
+			err := validateBatch()
+			if err != nil {
+				return fmt.Errorf("batch validation failed: %w",
+					err)
+			}
 		}
 
 		s.Do(func() {
@@ -239,6 +305,15 @@ func migrateNodes(ctx context.Context, cfg *sqldb.QueryConfig,
 		return fmt.Errorf("could not migrate nodes: %w", err)
 	}
 
+	// Validate any remaining nodes in the batch.
+	if len(batch) > 0 {
+		err := validateBatch()
+		if err != nil {
+			return fmt.Errorf("final batch validation failed: %w",
+				err)
+		}
+	}
+
 	log.Infof("Migrated %d nodes from KV to SQL (skipped %d nodes due to "+
 		"invalid TLV streams)", count, skipped)
 
diff --git a/graph/db/sql_store.go b/graph/db/sql_store.go
index 40d5525..de6c150 100644
--- a/graph/db/sql_store.go
+++ b/graph/db/sql_store.go
@@ -55,6 +55,7 @@ type SQLQueries interface {
 	*/
 	UpsertNode(ctx context.Context, arg sqlc.UpsertNodeParams) (int64, error)
 	GetNodeByPubKey(ctx context.Context, arg sqlc.GetNodeByPubKeyParams) (sqlc.GraphNode, error)
+	GetNodesByIDs(ctx context.Context, ids []int64) ([]sqlc.GraphNode, error)
 	GetNodeIDByPubKey(ctx context.Context, arg sqlc.GetNodeIDByPubKeyParams) (int64, error)
 	GetNodesByLastUpdateRange(ctx context.Context, arg sqlc.GetNodesByLastUpdateRangeParams) ([]sqlc.GraphNode, error)
 	ListNodesPaginated(ctx context.Context, arg sqlc.ListNodesPaginatedParams) ([]sqlc.GraphNode, error)
diff --git a/sqldb/sqlc/graph.sql.go b/sqldb/sqlc/graph.sql.go
index 6db5d32..5a81e52 100644
--- a/sqldb/sqlc/graph.sql.go
+++ b/sqldb/sqlc/graph.sql.go
@@ -1729,6 +1729,53 @@ func (q *Queries) GetNodeIDByPubKey(ctx context.Context, arg GetNodeIDByPubKeyPa
 	return id, err
 }
 
+const getNodesByIDs = `-- name: GetNodesByIDs :many
+SELECT id, version, pub_key, alias, last_update, color, signature
+FROM graph_nodes
+WHERE id IN (/*SLICE:ids*/?)
+`
+
+func (q *Queries) GetNodesByIDs(ctx context.Context, ids []int64) ([]GraphNode, error) {
+	query := getNodesByIDs
+	var queryParams []interface{}
+	if len(ids) > 0 {
+		for _, v := range ids {
+			queryParams = append(queryParams, v)
+		}
+		query = strings.Replace(query, "/*SLICE:ids*/?", makeQueryParams(len(queryParams), len(ids)), 1)
+	} else {
+		query = strings.Replace(query, "/*SLICE:ids*/?", "NULL", 1)
+	}
+	rows, err := q.db.QueryContext(ctx, query, queryParams...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []GraphNode
+	for rows.Next() {
+		var i GraphNode
+		if err := rows.Scan(
+			&i.ID,
+			&i.Version,
+			&i.PubKey,
+			&i.Alias,
+			&i.LastUpdate,
+			&i.Color,
+			&i.Signature,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const getNodesByLastUpdateRange = `-- name: GetNodesByLastUpdateRange :many
 SELECT id, version, pub_key, alias, last_update, color, signature
 FROM graph_nodes
diff --git a/sqldb/sqlc/querier.go b/sqldb/sqlc/querier.go
index 55fd74b..7f1ad9a 100644
--- a/sqldb/sqlc/querier.go
+++ b/sqldb/sqlc/querier.go
@@ -68,6 +68,7 @@ type Querier interface {
 	GetNodeFeaturesBatch(ctx context.Context, ids []int64) ([]GraphNodeFeature, error)
 	GetNodeFeaturesByPubKey(ctx context.Context, arg GetNodeFeaturesByPubKeyParams) ([]int32, error)
 	GetNodeIDByPubKey(ctx context.Context, arg GetNodeIDByPubKeyParams) (int64, error)
+	GetNodesByIDs(ctx context.Context, ids []int64) ([]GraphNode, error)
 	GetNodesByLastUpdateRange(ctx context.Context, arg GetNodesByLastUpdateRangeParams) ([]GraphNode, error)
 	GetPruneHashByHeight(ctx context.Context, blockHeight int64) ([]byte, error)
 	GetPruneTip(ctx context.Context) (GraphPruneLog, error)
diff --git a/sqldb/sqlc/queries/graph.sql b/sqldb/sqlc/queries/graph.sql
index ae276a5..55629a9 100644
--- a/sqldb/sqlc/queries/graph.sql
+++ b/sqldb/sqlc/queries/graph.sql
@@ -21,6 +21,11 @@ WHERE graph_nodes.last_update IS NULL
     OR EXCLUDED.last_update > graph_nodes.last_update
 RETURNING id;
 
+-- name: GetNodesByIDs :many
+SELECT *
+FROM graph_nodes
+WHERE id IN (sqlc.slice('ids')/*SLICE:ids*/);
+
 -- name: GetNodeByPubKey :one
 SELECT *
 FROM graph_nodes