AliasAwareOutputExpression Unary Physical Operators¶
AliasAwareOutputExpression
is an extension of the UnaryExecNode abstraction for unary physical operators with the output named expressions.
Contract¶
Output Named Expressions¶
outputExpressions: Seq[NamedExpression]
Output NamedExpressions
Used when:
AliasAwareOutputExpression
is requested for the aliasMap
Implementations¶
aliasMap¶
aliasMap: AttributeMap[Attribute]
aliasMap
is a collection of AttributeReference
expressions (of the Alias
expressions with the AttributeReference
expressions in the output named expressions) and the Alias
es converted to Attribute
s.
Lazy Value
aliasMap
is a Scala lazy value to guarantee that the code to initialize it is executed once only (when accessed for the first time) and the computed value never changes afterwards.
Learn more in the Scala Language Specification.
aliasMap
is used when:
AliasAwareOutputExpression
is requested to hasAlias and normalizeExpression
hasAlias¶
hasAlias: Boolean
hasAlias
is true
when the aliasMap is not empty.
hasAlias
is used when:
AliasAwareOutputPartitioning
is requested for the outputPartitioningAliasAwareOutputOrdering
is requested for the outputOrdering
normalizeExpression¶
normalizeExpression(
exp: Expression): Expression
normalizeExpression
...FIXME
normalizeExpression
is used when:
AliasAwareOutputPartitioning
is requested for the outputPartitioningAliasAwareOutputOrdering
is requested for the outputOrdering