Interface SchemaPlus

All Superinterfaces:
Schema

public interface SchemaPlus
extends Schema
Extension to the Schema interface.

Given a user-defined schema that implements the Schema interface, Calcite creates a wrapper that implements the SchemaPlus interface. This provides extra functionality, such as access to tables that have been added explicitly.

A user-defined schema does not need to implement this interface, but by the time a schema is passed to a method in a user-defined schema or user-defined table, it will have been wrapped in this interface.

SchemaPlus is intended to be used by users but not instantiated by them. Users should only use the SchemaPlus they are given by the system. The purpose of SchemaPlus is to expose to user code, in a read only manner, some of the extra information about schemas that Calcite builds up when a schema is registered. It appears in several SPI calls as context; for example SchemaFactory.create(SchemaPlus, String, java.util.Map) contains a parent schema that might be a wrapped instance of a user-defined Schema, or indeed might not.

  • Method Details

    • getParentSchema

      SchemaPlus getParentSchema()
      Returns the parent schema, or null if this schema has no parent.
    • getName

      String getName()
      Returns the name of this schema.

      The name must not be null, and must be unique within its parent. The root schema is typically named "".

    • getSubSchema

      SchemaPlus getSubSchema​(String name)
      Description copied from interface: Schema
      Returns a sub-schema with a given name, or null.
      Specified by:
      getSubSchema in interface Schema
      Parameters:
      name - Sub-schema name
      Returns:
      Sub-schema with a given name, or null
    • add

      SchemaPlus add​(String name, Schema schema)
      Adds a schema as a sub-schema of this schema, and returns the wrapped object.
    • add

      void add​(String name, Table table)
      Adds a table to this schema.
    • add

      void add​(String name, Function function)
      Adds a function to this schema.
    • add

      void add​(String name, RelProtoDataType type)
      Adds a type to this schema.
    • add

      void add​(String name, Lattice lattice)
      Adds a lattice to this schema.
    • isMutable

      boolean isMutable()
      Description copied from interface: Schema
      Returns whether the user is allowed to create new tables, functions and sub-schemas in this schema, in addition to those returned automatically by methods such as Schema.getTable(String).

      Even if this method returns true, the maps are not modified. Calcite stores the defined objects in a wrapper object.

      Specified by:
      isMutable in interface Schema
      Returns:
      Whether the user is allowed to create new tables, functions and sub-schemas in this schema
    • unwrap

      <T> T unwrap​(Class<T> clazz)
      Returns an underlying object.
    • setPath

      void setPath​(com.google.common.collect.ImmutableList<com.google.common.collect.ImmutableList<String>> path)
    • setCacheEnabled

      void setCacheEnabled​(boolean cache)
    • isCacheEnabled

      boolean isCacheEnabled()