MetadataColumnHelper Implicit Class¶
MetadataColumnHelper
is a Scala implicit class for Attribute.
Creating Instance¶
MetadataColumnHelper
takes the following to be created:
isMetadataCol¶
isMetadataCol: Boolean
isMetadataCol
takes the Metadata of the Attribute and checks if there is the __metadata_col key with true
value.
isMetadataCol
is used when:
- AddMetadataColumns logical resolution rule is executed
markAsQualifiedAccessOnly¶
markAsQualifiedAccessOnly(): Attribute
markAsQualifiedAccessOnly
propagates hidden columns by adding the following metadata to the Attribute:
Metadata Key | Value |
---|---|
__metadata_col | true |
__qualified_access_only | true |
markAsQualifiedAccessOnly
is used when:
Analyzer
is requested to commonNaturalJoinProcessing