CsvProjectTableScanRule (Apache Calcite API)

java.lang.Object
- org.apache.calcite.plan.RelOptRule
- - org.apache.calcite.adapter.csv.CsvProjectTableScanRule

```
public class CsvProjectTableScanRule
extends RelOptRule
```
Planner rule that projects from a CsvTableScan scan just the columns needed to satisfy a projection. If the projection's expressions are trivial, the projection is removed.

Field Summary

Fields
Modifier and Type Field Description

static CsvProjectTableScanRule INSTANCE
- Fields inherited from class org.apache.calcite.plan.RelOptRule
  description, operands, relBuilderFactory

Constructor Summary

Constructors
Constructor Description

CsvProjectTableScanRule(RelBuilderFactory relBuilderFactory)
Creates a CsvProjectTableScanRule.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private int[]`	`getProjectFields(java.util.List<RexNode> exps)`
`void`	`onMatch(RelOptRuleCall call)`	Receives notification about a rule match.

Methods inherited from class org.apache.calcite.plan.RelOptRule
any, convert, convert, convertList, convertOperand, convertOperand, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, matches, none, operand, operand, operand, operand, operand, operandJ, operandJ, some, toString, unordered

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - INSTANCE
```
public static final CsvProjectTableScanRule INSTANCE
```
- Constructor Detail
  - CsvProjectTableScanRule
```
public CsvProjectTableScanRule(RelBuilderFactory relBuilderFactory)
```
    Creates a CsvProjectTableScanRule.
    
    Parameters:
    
    relBuilderFactory - Builder for relational expressions
- Method Detail
  - onMatch
```
public void onMatch(RelOptRuleCall call)
```
    Description copied from class: RelOptRule
    
    Receives notification about a rule match. At the time that this method is called, call.rels holds the set of relational expressions which match the operands to the rule; call.rels[0] is the root expression.
    Typically a rule would check that the nodes are valid matches, creates a new expression, then calls back RelOptRuleCall.transformTo(org.apache.calcite.rel.RelNode, java.util.Map<org.apache.calcite.rel.RelNode, org.apache.calcite.rel.RelNode>) to register the expression.
    
    Specified by:
    
    onMatch in class RelOptRule
    
    Parameters:
    
    call - Rule call
    
    See Also:
    
    RelOptRule.matches(RelOptRuleCall)
  - getProjectFields
```
private int[] getProjectFields(java.util.List<RexNode> exps)
```