Package org.apache.calcite.adapter.jdbc

Class JdbcConvention

java.lang.Object

org.apache.calcite.plan.Convention.Impl

org.apache.calcite.adapter.jdbc.JdbcConvention

All Implemented Interfaces:

Convention, RelTrait

public class JdbcConvention
extends Convention.Impl

Calling convention for relational operations that occur in a JDBC database.

The convention is a slight misnomer. The operations occur in whatever data-flow architecture the database uses internally. Nevertheless, the result pops out in JDBC.

This is the only convention, thus far, that is not a singleton. Each instance contains a JDBC schema (and therefore a data source). If Calcite is working with two different databases, it would even make sense to convert from "JDBC#A" convention to "JDBC#B", even though we don't do it currently. (That would involve asking database B to open a database link to database A.)

As a result, converter rules from and to this convention need to be instantiated, at the start of planning, for each JDBC database in play.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.calcite.plan.Convention

Convention.Impl

Field Summary

Fields

Modifier and Type	Field	Description
static final double	COST_MULTIPLIER	Cost of a JDBC node versus implementing an equivalent node in a "typical" calling convention.
final SqlDialect	dialect
final Expression	expression

Fields inherited from interface org.apache.calcite.plan.Convention

NONE

Constructor Summary

Constructors

Constructor	Description
JdbcConvention(SqlDialect dialect, Expression expression, String name)

Method Summary

Modifier and Type	Method	Description
static JdbcConvention	of(SqlDialect dialect, Expression expression, String name)
void	register(RelOptPlanner planner)	Registers a trait instance with the planner.

Methods inherited from class org.apache.calcite.plan.Convention.Impl

canConvertConvention, enforce, getInterface, getName, getTraitDef, satisfies, toString, useAbstractConvertersForConversion

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.calcite.plan.Convention

getRelFactories

Methods inherited from interface org.apache.calcite.plan.RelTrait

apply, equals, hashCode, isDefault

Field Details

COST_MULTIPLIER

public static final double COST_MULTIPLIER

Cost of a JDBC node versus implementing an equivalent node in a "typical" calling convention.

See Also:

• Constant Field Values

dialect

public final SqlDialect dialect

expression

public final Expression expression

Constructor Details

JdbcConvention

public JdbcConvention(SqlDialect dialect,
 Expression expression,
 String name)

Method Details

of

public static JdbcConvention of(SqlDialect dialect,
 Expression expression,
 String name)

register

public void register(RelOptPlanner planner)

Description copied from interface: RelTrait

Registers a trait instance with the planner.

This is an opportunity to add rules that relate to that trait. However, typical implementations will do nothing.

Specified by:

register in interface RelTrait

Overrides:

register in class Convention.Impl

Parameters:

planner - Planner