Package org.apache.calcite.rel.metadata

Class RelMetadataQueryBase

java.lang.Object

org.apache.calcite.rel.metadata.RelMetadataQueryBase

Direct Known Subclasses:

RelMetadataQuery

public class RelMetadataQueryBase
extends Object

Base class for the RelMetadataQuery that uses the metadata handler class generated by the Janino.

To add a new implementation to this interface, follow these steps:

1. Extends RelMetadataQuery (name it MyRelMetadataQuery for example) to reuse the Calcite builtin metadata query interfaces. In this class, define all the extended Handlers for your metadata and implement the metadata query interfaces.
2. Write your customized provider class RelMdXyz. Follow the pattern from an existing class such as RelMdColumnOrigins, overloading on all of the logical relational expressions to which the query applies.
3. Add a SOURCE static member to each of your provider class, similar to RelMdColumnOrigins.SOURCE.
4. Extends DefaultRelMetadataProvider (name it MyRelMetadataProvider for example) and supplement the "SOURCE"s into the builtin list (This is not required, use ChainedRelMetadataProvider to chain your customized "SOURCE"s with default ones also works).
5. Set MyRelMetadataProvider into the cluster instance.
6. Use RelOptCluster.setMetadataQuerySupplier(Supplier) to set the metadata query Supplier into the cluster instance. This Supplier should return a fresh new instance.
7. Use the cluster instance to create SqlToRelConverter.
8. Query your metadata within RelOptRuleCall with the interfaces you defined in MyRelMetadataQuery.

Field Summary

Fields

Modifier and Type	Field	Description
final com.google.common.collect.Table<RelNode,Object,Object>	map	Set of active metadata queries, and cache of previous results.
final @Nullable JaninoRelMetadataProvider	metadataProvider	Deprecated.
static final ThreadLocal<@Nullable JaninoRelMetadataProvider>	THREAD_PROVIDERS

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	RelMetadataQueryBase(@Nullable JaninoRelMetadataProvider metadataProvider)	Deprecated.
protected	RelMetadataQueryBase(@Nullable MetadataHandlerProvider provider)

Method Summary

Modifier and Type	Method	Description
boolean	clearCache(RelNode rel)	Removes cached metadata values for specified RelNode.
protected <MH extends MetadataHandler<?>> MH	handler(Class<MH> handlerClass)	Provide a handler for the requested metadata class.
protected static <H> H	initialHandler(Class<H> handlerClass)	Deprecated.
protected <M extends Metadata, H extends MetadataHandler<M>> H	revise(Class<? extends RelNode> class_, MetadataDef<M> def)	Deprecated.
protected <H extends MetadataHandler<?>> H	revise(Class<H> def)	Re-generates the handler for a given kind of metadata, adding support for class_ if it is not already present.

Methods inherited from class java.lang.Object

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

Field Details

map

public final com.google.common.collect.Table<RelNode,Object,Object> map

Set of active metadata queries, and cache of previous results.

metadataProvider

@Deprecated
public final @Nullable JaninoRelMetadataProvider metadataProvider

Deprecated.

THREAD_PROVIDERS

public static final ThreadLocal<@Nullable JaninoRelMetadataProvider> THREAD_PROVIDERS

Constructor Details

RelMetadataQueryBase

@Deprecated
protected RelMetadataQueryBase(@Nullable JaninoRelMetadataProvider metadataProvider)

Deprecated.

RelMetadataQueryBase

protected RelMetadataQueryBase(@Nullable MetadataHandlerProvider provider)

Method Details

initialHandler

@Deprecated
protected static <H> H initialHandler(Class<H> handlerClass)

Deprecated.

revise

@Deprecated
protected <M extends Metadata,
H extends MetadataHandler<M>>
H revise(Class<? extends RelNode> class_,
 MetadataDef<M> def)

Deprecated.

Re-generates the handler for a given kind of metadata, adding support for class_ if it is not already present.

revise

protected <H extends MetadataHandler<?>> H revise(Class<H> def)

Re-generates the handler for a given kind of metadata, adding support for class_ if it is not already present.

handler

protected <MH extends MetadataHandler<?>> MH handler(Class<MH> handlerClass)

Provide a handler for the requested metadata class.

Type Parameters:

MH - The metadata type the handler relates to.

Parameters:

handlerClass - The handler interface expected

Returns:

The handler implementation.

clearCache

public boolean clearCache(RelNode rel)

Removes cached metadata values for specified RelNode.

Parameters:

rel - RelNode whose cached metadata should be removed

Returns:

true if cache for the provided RelNode was not empty