org.apache.calcite.schema.impl

Class AbstractSchema

java.lang.Object

org.apache.calcite.schema.impl.AbstractSchema

All Implemented Interfaces:

Schema

Direct Known Subclasses:

CloneSchema, ReflectiveSchema

public class AbstractSchema
extends Object
implements Schema

Abstract implementation of Schema.

Behavior is as follows:

• The schema has no tables unless you override getTableMap().
• The schema has no functions unless you override getFunctionMultimap().
• The schema has no sub-schemas unless you override getSubSchemaMap().
• The schema is mutable unless you override isMutable().
• The name and parent schema are as specified in the constructor arguments.

For constructing custom maps and multi-maps, we recommend Suppliers and Maps.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.calcite.schema.Schema

Schema.TableType

Constructor Summary

Constructors

Constructor and Description
AbstractSchema()

Method Summary

Methods

Modifier and Type	Method and Description
boolean	contentsHaveChangedSince(long lastCheck, long now) Returns whether the contents of this schema have changed since a given time.
Expression	getExpression(SchemaPlus parentSchema, String name) Returns the expression by which this schema can be referenced in generated code.
protected com.google.common.collect.Multimap<String,Function>	getFunctionMultimap() Returns a multi-map of functions in this schema by name.
Set<String>	getFunctionNames() Returns the names of the functions in this schema.
Collection<Function>	getFunctions(String name) Returns a list of functions in this schema with the given name, or an empty list if there is no such function.
Schema	getSubSchema(String name) Returns a sub-schema with a given name, or null.
protected Map<String,Schema>	getSubSchemaMap() Returns a map of sub-schemas in this schema by name.
Set<String>	getSubSchemaNames() Returns the names of this schema's child schemas.
Table	getTable(String name) Returns a table with a given name, or null if not found.
protected Map<String,Table>	getTableMap() Returns a map of tables in this schema by name.
Set<String>	getTableNames() Returns the names of the tables in this schema.
boolean	isMutable() 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).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AbstractSchema

public AbstractSchema()

Method Detail

isMutable

public 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

contentsHaveChangedSince

public boolean contentsHaveChangedSince(long lastCheck,
                               long now)

Description copied from interface: Schema

Returns whether the contents of this schema have changed since a given time. The time is a millisecond value, as returned by System.currentTimeMillis(). If this method returns true, and caching is enabled, Calcite will re-build caches.

The default implementation in AbstractSchema always returns false.

To control whether Calcite caches the contents of a schema, use the "cache" JSON attribute. The default value is "true".

Specified by:

contentsHaveChangedSince in interface Schema

Parameters:

lastCheck - The last time that Calcite called this method, or Long.MIN_VALUE if this is the first call

now - The current time in millis, as returned by System.currentTimeMillis()

Returns:

Whether contents changed after lastCheckMillis.

getExpression

public Expression getExpression(SchemaPlus parentSchema,
                       String name)

Description copied from interface: Schema

Returns the expression by which this schema can be referenced in generated code.

Specified by:

getExpression in interface Schema

Parameters:

parentSchema - Parent schema

name - Name of this schema

Returns:

Expression by which this schema can be referenced in generated code

getTableMap

protected Map<String,Table> getTableMap()

Returns a map of tables in this schema by name.

The implementations of getTableNames() and getTable(String) depend on this map. The default implementation of this method returns the empty map. Override this method to change their behavior.

Returns:

Map of tables in this schema by name

getTableNames

public final Set<String> getTableNames()

Description copied from interface: Schema

Returns the names of the tables in this schema.

Specified by:

getTableNames in interface Schema

Returns:

Names of the tables in this schema

getTable

public final Table getTable(String name)

Description copied from interface: Schema

Returns a table with a given name, or null if not found.

Specified by:

getTable in interface Schema

Parameters:

name - Table name

Returns:

Table, or null

getFunctionMultimap

protected com.google.common.collect.Multimap<String,Function> getFunctionMultimap()

Returns a multi-map of functions in this schema by name. It is a multi-map because functions are overloaded; there may be more than one function in a schema with a given name (as long as they have different parameter lists).

The implementations of getFunctionNames() and Schema.getFunctions(String) depend on this map. The default implementation of this method returns the empty multi-map. Override this method to change their behavior.

Returns:

Multi-map of functions in this schema by name

getFunctions

public final Collection<Function> getFunctions(String name)

Description copied from interface: Schema

Returns a list of functions in this schema with the given name, or an empty list if there is no such function.

Specified by:

getFunctions in interface Schema

Parameters:

name - Name of function

Returns:

List of functions with given name, or empty list

getFunctionNames

public final Set<String> getFunctionNames()

Description copied from interface: Schema

Returns the names of the functions in this schema.

Specified by:

getFunctionNames in interface Schema

Returns:

Names of the functions in this schema

getSubSchemaMap

protected Map<String,Schema> getSubSchemaMap()

Returns a map of sub-schemas in this schema by name.

The implementations of getSubSchemaNames() and getSubSchema(String) depend on this map. The default implementation of this method returns the empty map. Override this method to change their behavior.

Returns:

Map of sub-schemas in this schema by name

getSubSchemaNames

public final Set<String> getSubSchemaNames()

Description copied from interface: Schema

Returns the names of this schema's child schemas.

Specified by:

getSubSchemaNames in interface Schema

Returns:

Names of this schema's child schemas

getSubSchema

public final Schema 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