perf: do a bulk insert in fetchCollection

Improve performance over inserting each item individually

pkg/synchronizator.go

@@ -451,3 +451,67 @@ func (conn *DB) DeleteRelation(from int64, to int64) error {
 
 	return nil
 }
+
+// Creates a new node
+func BulkCreateNode[T StandardNode](
+	conn *DB,
+	nodes []T,
+) error {
+	if len(nodes) == 0 {
+		return nil
+	}
+
+	tx, err := conn.Connection.Begin()
+	if err != nil {
+		return err
+	}
+
+	defer tx.Rollback()
+
+	// Build the query dynamically based on number of nodes
+	valueStrings := make([]string, 0, len(nodes))
+	valueArgs := make([]interface{}, 0, len(nodes)*3)
+
+	for i := range nodes {
+		// Create ($1, $2, $3), ($4, $5, $6), etc.
+		n := i * 3
+		valueStrings = append(valueStrings, fmt.Sprintf("($%d, $%d, $%d)", n+1, n+2, n+3))
+		valueArgs = append(
+			valueArgs,
+			nodes[i].GetClass(),
+			nodes[i].GetName(),
+			nodes[i].GetMetadata(),
+		)
+	}
+
+	sql := fmt.Sprintf(`
+        INSERT INTO nodes (_class, name, metadata) 
+        VALUES %s 
+        RETURNING id;`, strings.Join(valueStrings, ","))
+
+	conn.log(DEBUG, "Bulk creating nodes:", sql, valueArgs)
+
+	// Execute and scan returned IDs
+	rows, err := tx.Query(sql, valueArgs...)
+	if err != nil {
+		return fmt.Errorf("bulk insert failed: %w", err)
+	}
+	defer rows.Close()
+
+	// Assign IDs back to the nodes
+	i := 0
+	for rows.Next() {
+		var id int64
+		if err := rows.Scan(&id); err != nil {
+			return fmt.Errorf("scanning returned id failed: %w", err)
+		}
+
+		nodes[i].SetId(id)
+		nodes[i].SetConnection(conn)
+		i++
+	}
+
+	tx.Commit()
+
+	return rows.Err()
+}