You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mod.rs
    path of file: ./repos/readyset/readyset-server/src/controller/migrate/materialization
    
    the code of the file until where you have to start completion: //! Functions for identifying which nodes should be materialized, and what indices should be used
//! for those ma
    
    pub(in crate::controller) fn new() -> Self {
        Materializations {
            have: HashMap::default(),
            had: HashSet::default(),
            added: HashMap::default(),
            new_readers: HashSet::default(),

            added_weak: HashMap::default(),

            paths: HashMap::default(),

            redundant_partial: HashMap::default(),

            partial: HashSet::default(),

            tag_generator: 0,

            config: Default::default(),
        }
    }