PushProjectionThroughExchange (presto-main 312 API)

public class PushProjectionThroughExchange
extends Object
implements Rule<ProjectNode>

Transforms:

  Project(x = e1, y = e2)
    Exchange()
      Source(a, b, c)

to:

  Exchange()
    Project(x = e1, y = e2)
      Source(a, b, c)

Or if Exchange needs symbols from Source for partitioning or as hash symbol to:

  Project(x, y)
    Exchange()
      Project(x = e1, y = e2, a)
        Source(a, b, c)

To avoid looping this optimizer will not be fired if upper Project contains just symbol references.

Nested Class Summary
- Nested classes/interfaces inherited from interface io.prestosql.sql.planner.iterative.Rule
  Rule.Context, Rule.Result

Constructors
Constructor and Description
`PushProjectionThroughExchange()`

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Rule.Result`	`apply(ProjectNode project, Captures captures, Rule.Context context)`
`Pattern<ProjectNode>`	`getPattern()` Returns a pattern to which plan nodes this rule applies.

Methods inherited from interface io.prestosql.sql.planner.iterative.Rule
isEnabled

Constructor Detail
- PushProjectionThroughExchange
```
public PushProjectionThroughExchange()
```

public Rule.Result apply(ProjectNode project,
                         Captures captures,
                         Rule.Context context)

Class PushProjectionThroughExchange