public class PushProjector
extends java.lang.Object
Pushing is particularly interesting in the case of join, because there are multiple inputs. Generally an expression can be pushed down to a particular input if it depends upon no other inputs. If it can be pushed down to both sides, it is pushed down to the left.
Sometimes an expression needs to be split before it can be pushed down. To flag that an expression cannot be split, specify a rule that it must be preserved. Such an expression will be pushed down intact to one of the inputs, or not pushed down at all.
Modifier and Type | Class and Description |
---|---|
static interface |
PushProjector.ExprCondition
A functor that replies true or false for a given expression.
|
private class |
PushProjector.InputSpecialOpFinder
Visitor which builds a bitmap of the inputs used by an expressions, as
well as locating expressions corresponding to special operators.
|
(package private) class |
PushProjector.OperatorExprCondition
An expression condition that evaluates to true if the expression is
a call to one of a set of operators.
|
private class |
PushProjector.RefAndExprConverter
Walks an expression tree, replacing input refs with new values to reflect
projection and converting special expressions to field references.
|
Modifier and Type | Field and Description |
---|---|
(package private) ImmutableBitSet |
childBitmap
Bitmap containing the fields in the RelNode that the projection is being
pushed past, if the RelNode is not a join.
|
(package private) java.util.List<RelDataTypeField> |
childFields
Fields from the RelNode that the projection is being pushed past
|
(package private) java.util.List<RexNode> |
childPreserveExprs
Expressions referenced in the projection/filter that should be preserved.
|
private RelNode |
childRel |
(package private) int |
nChildFields
Number of fields in the RelNode that the projection is being pushed past
|
(package private) int |
nFields
Number of fields in the RelNode that the projection is being pushed past,
if the RelNode is not a join.
|
(package private) int |
nFieldsRight
Number of fields in the right hand side of a join, in the case where the
projection is being pushed past a join.
|
(package private) int |
nProject
Number of fields being projected.
|
(package private) int |
nRightProject
Number of fields being projected from the right hand side of a join, in
the case where the projection is being pushed past a join.
|
private int |
nSysFields
Number of system fields.
|
(package private) int |
nSystemProject
Number of system fields being projected.
|
private RexNode |
origFilter |
private Project |
origProj |
(package private) java.util.List<RexNode> |
origProjExprs
Original projection expressions
|
private PushProjector.ExprCondition |
preserveExprCondition |
(package private) java.util.BitSet |
projRefs
Bitmap containing the references in the original projection
|
private RelBuilder |
relBuilder |
(package private) RexBuilder |
rexBuilder
Rex builder used to create new expressions.
|
(package private) ImmutableBitSet |
rightBitmap
Bitmap containing the fields in the right hand side of a join, in the
case where the projection is being pushed past a join.
|
(package private) java.util.List<RexNode> |
rightPreserveExprs
Expressions referenced in the projection/filter that should be preserved,
corresponding to expressions on the right hand side of the join, if the
projection is being pushed past a join.
|
(package private) ImmutableBitSet |
strongBitmap
Bitmap containing the fields that should be strong, i.e.
|
Constructor and Description |
---|
PushProjector(Project origProj,
RexNode origFilter,
RelNode childRel,
PushProjector.ExprCondition preserveExprCondition,
RelBuilder relBuilder)
Creates a PushProjector object for pushing projects past a RelNode.
|
Modifier and Type | Method and Description |
---|---|
RelNode |
convertProject(RexNode defaultExpr)
Decomposes a projection to the input references referenced by a
projection and a filter, either of which is optional.
|
RexNode |
convertRefsAndExprs(RexNode rex,
java.util.List<RelDataTypeField> destFields,
int[] adjustments)
Clones an expression tree and walks through it, adjusting each
RexInputRef index by some amount, and converting expressions that need to
be preserved to field references.
|
RelNode |
createNewProject(RelNode projChild,
int[] adjustments)
Creates a new projection based on the original projection, adjusting all
input refs using an adjustment array passed in.
|
Project |
createProjectRefsAndExprs(RelNode projChild,
boolean adjust,
boolean rightSide)
Creates a projection based on the inputs specified in a bitmap and the
expressions that need to be preserved.
|
int[] |
getAdjustments()
Determines how much each input reference needs to be adjusted as a result
of projection
|
boolean |
locateAllRefs()
Locates all references found in either the projection expressions a
filter, as well as references to expressions that should be preserved.
|
private final Project origProj
private final RexNode origFilter
private final RelNode childRel
private final PushProjector.ExprCondition preserveExprCondition
private final RelBuilder relBuilder
final java.util.List<RexNode> origProjExprs
final java.util.List<RelDataTypeField> childFields
final int nChildFields
final java.util.BitSet projRefs
final ImmutableBitSet childBitmap
final ImmutableBitSet rightBitmap
final ImmutableBitSet strongBitmap
final int nFields
The identity
nChildFields == nSysFields + nFields + nFieldsRight
holds. nFields
does not include nSysFields
.
The output of a join looks like this:
| nSysFields | nFields | nFieldsRight |
The output of a single-input rel looks like this:
| nSysFields | nFields |
final int nFieldsRight
private final int nSysFields
final java.util.List<RexNode> childPreserveExprs
final java.util.List<RexNode> rightPreserveExprs
int nSystemProject
int nProject
int nRightProject
final RexBuilder rexBuilder
public PushProjector(Project origProj, RexNode origFilter, RelNode childRel, PushProjector.ExprCondition preserveExprCondition, RelBuilder relBuilder)
origProj
- the original projection that is being pushed;
may be null if the projection is implied as a
result of a projection having been trivially
removedorigFilter
- the filter that the projection must also be
pushed past, if applicablechildRel
- the RelNode that the projection is being
pushed pastpreserveExprCondition
- condition for whether an expression should
be preserved in the projectionpublic RelNode convertProject(RexNode defaultExpr)
Creates a projection containing all input references as well as preserving any special expressions. Converts the original projection and/or filter to reference the new projection. Then, finally puts on top, a final projection corresponding to the original projection.
defaultExpr
- expression to be used in the projection if no fields
or special columns are selectedpublic boolean locateAllRefs()
public Project createProjectRefsAndExprs(RelNode projChild, boolean adjust, boolean rightSide)
projChild
- child that the projection will be created on top ofadjust
- if true, need to create new projection expressions;
otherwise, the existing ones are reusedrightSide
- if true, creating a projection for the right hand side
of a joinpublic int[] getAdjustments()
public RexNode convertRefsAndExprs(RexNode rex, java.util.List<RelDataTypeField> destFields, int[] adjustments)
rex
- the expressiondestFields
- fields that the new expressions will be referencingadjustments
- the amount each input reference index needs to be
adjusted bypublic RelNode createNewProject(RelNode projChild, int[] adjustments)
If the resulting projection would be trivial, return the child.
projChild
- child of the new projectadjustments
- array indicating how much each input reference should
be adjusted byCopyright © 2012–2019 The Apache Software Foundation. All rights reserved.