JdbcConvention (Apache Calcite API)

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 two 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 double`	`COST_MULTIPLIER`	Cost of a JDBC node versus implementing an equivalent node in a "typical" calling convention.
`SqlDialect`	`dialect`
`Expression`	`expression`

Fields inherited from interface org.apache.calcite.plan.Convention
NONE

Constructor Summary

Constructors
Constructor Description

JdbcConvention(SqlDialect dialect, Expression expression, java.lang.String name)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`static JdbcConvention`	`of(SqlDialect dialect, Expression expression, java.lang.String name)`
`void`	`register(RelOptPlanner planner)`	Registers a trait instance with the planner.

Methods inherited from class org.apache.calcite.plan.Convention.Impl
canConvertConvention, 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.RelTrait
equals, hashCode

Field Detail
- 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 Detail

JdbcConvention

public JdbcConvention(SqlDialect dialect,
                      Expression expression,
                      java.lang.String name)

Method Detail
- of
```
public static JdbcConvention of(SqlDialect dialect,
                                Expression expression,
                                java.lang.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