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 entries to the metadata of this Attribute:
| Metadata Key | Value |
|---|---|
| __metadata_col | The name of this Attribute |
| __qualified_access_only | true |
markAsQualifiedAccessOnly is used when:
Analyzeris requested to commonNaturalJoinProcessing