org.apache.calcite.rel.core

Class TableScan

java.lang.Object

org.apache.calcite.rel.AbstractRelNode

org.apache.calcite.rel.core.TableScan

All Implemented Interfaces:

Cloneable, RelOptNode, RelNode

Direct Known Subclasses:

Bindables.BindableTableScan, EnumerableTableScan, JdbcTableScan, LogicalTableScan, StarTable.StarTableScan

public abstract class TableScan
extends AbstractRelNode

Relational operator that returns the contents of a table.

Field Summary

Fields

Modifier and Type	Field and Description
protected RelOptTable	table The table definition.

Fields inherited from class org.apache.calcite.rel.AbstractRelNode

digest, id, rowType, traitSet

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	TableScan(RelInput input) Creates a TableScan by parsing serialized output.
protected	TableScan(RelOptCluster cluster, RelTraitSet traitSet, RelOptTable table)

Method Summary

Methods

Modifier and Type	Method and Description
RelNode	accept(RelShuttle shuttle) Accepts a visit from a shuttle.
RelOptCost	computeSelfCost(RelOptPlanner planner) Returns the cost of this plan (not including children).
RelDataType	deriveRowType()
RelWriter	explainTerms(RelWriter pw) Describes the inputs and attributes of this relational expression.
List<RelCollation>	getCollationList() Returns a description of the physical ordering (or orderings) of this relational expression.
double	getRows() Returns an estimate of the number of rows this relational expression will return.
RelOptTable	getTable() If this relational expression represents an access to a table, returns that table, otherwise returns null.
ImmutableIntList	identity() Returns an identity projection.
static ImmutableIntList	identity(RelOptTable table) Returns an identity projection for the given table.
boolean	isKey(ImmutableBitSet columns) Returns whether the result of this relational expression is uniquely identified by this columns with the given ordinals.
RelNode	project(ImmutableBitSet fieldsUsed, Set<RelDataTypeField> extraFields, RelFactories.ProjectFactory projectFactory) Projects a subset of the fields of the table, and also asks for "extra" fields that were not included in the table's official type.

Methods inherited from class org.apache.calcite.rel.AbstractRelNode

accept, childrenAccept, collectVariablesSet, collectVariablesUsed, computeDigest, copy, explain, getChildExps, getCluster, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getInputs, getQuery, getRelTypeName, getRowType, getTraitSet, getVariablesStopped, isDistinct, isValid, metadata, onRegister, recomputeDigest, register, replaceInput, sole, toString

Methods inherited from class java.lang.Object

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

Field Detail

table

protected final RelOptTable table

The table definition.

Constructor Detail

TableScan

protected TableScan(RelOptCluster cluster,
         RelTraitSet traitSet,
         RelOptTable table)

TableScan

protected TableScan(RelInput input)

Creates a TableScan by parsing serialized output.

Method Detail

getRows

public double getRows()

Description copied from interface: RelNode

Returns an estimate of the number of rows this relational expression will return.

NOTE jvs 29-Mar-2006: Don't call this method directly. Instead, use RelMetadataQuery.getRowCount(org.apache.calcite.rel.RelNode), which gives plugins a chance to override the rel's default ideas about row count.

Specified by:

getRows in interface RelNode

Overrides:

getRows in class AbstractRelNode

Returns:

Estimate of the number of rows this relational expression will return

getTable

public RelOptTable getTable()

Description copied from interface: RelNode

If this relational expression represents an access to a table, returns that table, otherwise returns null.

Specified by:

getTable in interface RelNode

Overrides:

getTable in class AbstractRelNode

Returns:

If this relational expression represents an access to a table, returns that table, otherwise returns null

getCollationList

public List<RelCollation> getCollationList()

Description copied from interface: RelNode

Returns a description of the physical ordering (or orderings) of this relational expression. Never null.

Specified by:

getCollationList in interface RelNode

Overrides:

getCollationList in class AbstractRelNode

Returns:

Description of the physical ordering (or orderings) of this relational expression. Never null

isKey

public boolean isKey(ImmutableBitSet columns)

Description copied from interface: RelNode

Returns whether the result of this relational expression is uniquely identified by this columns with the given ordinals.

For example, if this relational expression is a LogicalTableScan to T(A, B, C, D) whose key is (A, B), then isKey([0, 1]) yields true, and isKey([0]) and isKey([0, 2]) yields false.

Specified by:

isKey in interface RelNode

Overrides:

isKey in class AbstractRelNode

Parameters:

columns - Ordinals of key columns

Returns:

Whether the given columns are a key or a superset of a key

computeSelfCost

public RelOptCost computeSelfCost(RelOptPlanner planner)

Description copied from interface: RelNode

Returns the cost of this plan (not including children). The base implementation throws an error; derived classes should override.

NOTE jvs 29-Mar-2006: Don't call this method directly. Instead, use RelMetadataQuery.getNonCumulativeCost(org.apache.calcite.rel.RelNode), which gives plugins a chance to override the rel's default ideas about cost.

Specified by:

computeSelfCost in interface RelNode

Overrides:

computeSelfCost in class AbstractRelNode

Parameters:

planner - Planner for cost calculation

Returns:

Cost of this plan (not including children)

deriveRowType

public RelDataType deriveRowType()

Overrides:

deriveRowType in class AbstractRelNode

identity

public static ImmutableIntList identity(RelOptTable table)

Returns an identity projection for the given table.

identity

public ImmutableIntList identity()

Returns an identity projection.

explainTerms

public RelWriter explainTerms(RelWriter pw)

Description copied from class: AbstractRelNode

Describes the inputs and attributes of this relational expression. Each node should call super.explainTerms, then call the RelWriterImpl.input(String, RelNode) and RelWriterImpl.item(String, Object) methods for each input and attribute.

Overrides:

explainTerms in class AbstractRelNode

Parameters:

pw - Plan writer

Returns:

Plan writer for fluent-explain pattern

project

public RelNode project(ImmutableBitSet fieldsUsed,
              Set<RelDataTypeField> extraFields,
              RelFactories.ProjectFactory projectFactory)

Projects a subset of the fields of the table, and also asks for "extra" fields that were not included in the table's official type.

The default implementation assumes that tables cannot do either of these operations, therefore it adds a LogicalProject, projecting NULL values for the extra fields.

Sub-classes, representing table types that have these capabilities, should override.

Parameters:

fieldsUsed - Bitmap of the fields desired by the consumer

extraFields - Extra fields, not advertised in the table's row-type, wanted by the consumer

Returns:

Relational expression that projects the desired fields

accept

public RelNode accept(RelShuttle shuttle)

Description copied from interface: RelNode

Accepts a visit from a shuttle.

Specified by:

accept in interface RelNode

Overrides:

accept in class AbstractRelNode

Parameters:

shuttle - Shuttle

Returns:

A copy of this node incorporating changes made by the shuttle to this node's children