public List<HiveRelOptMaterialization> values() {
    List<HiveRelOptMaterialization> result = new ArrayList<>();
    materializedViews.forEach((dbName, mvs) -> result.addAll(mvs.values()));
    return unmodifiableList(result);
  }
Collection for storing {@link HiveRelOptMaterialization}s.
Materialization can be lookup by
- the Materialized View fully qualified name
- query text.
This implementation contains two {@link ConcurrentHashMap} one for name based and one for query text based lookup.
The map contents are synchronized during each dml operation: Dml operations are performed initially on the map
which provides name based lookup. The map which provides query text based lookup is updated by lambda expressions
passed to {@link ConcurrentHashMap#compute(Object, BiFunction)}.
ql/src/java/org/apache/hadoop/hive/ql/metadata/MaterializedViewsCache.java