private static class SubstitutionVisitor.TrivialRule extends SubstitutionVisitor.AbstractUnifyRule
SubstitutionVisitor.UnifyRule
that matches if the query is already
equal to the target.
Matches scans to the same table, because these will be
MutableScan
s with the same
LogicalTableScan
instance.
Modifier and Type | Field and Description |
---|---|
private static SubstitutionVisitor.TrivialRule |
INSTANCE |
queryOperand, slotCount, targetOperand
Modifier | Constructor and Description |
---|---|
private |
TrivialRule() |
Modifier and Type | Method and Description |
---|---|
SubstitutionVisitor.UnifyResult |
apply(SubstitutionVisitor.UnifyRuleCall call)
Applies this rule to a particular node in a query.
|
any, isValid, operand, query, target
copy, match
private static final SubstitutionVisitor.TrivialRule INSTANCE
public SubstitutionVisitor.UnifyResult apply(SubstitutionVisitor.UnifyRuleCall call)
SubstitutionVisitor.UnifyRule
Applies this rule to a particular node in a query. The goal is
to convert query
into target
. Before the rule is
invoked, Calcite has made sure that query's children are equivalent
to target's children.
There are 3 possible outcomes:
query
already exactly matches target
; returns
target
query
is sufficiently close to a match for
target
; returns target
query
cannot be made to match target
; returns
nullREVIEW: Is possible that we match query PLUS one or more of its ancestors?
apply
in class SubstitutionVisitor.UnifyRule
call
- Input parametersCopyright © 2012–2019 The Apache Software Foundation. All rights reserved.