Interface NormalizationOperation

copy - Copies the value of the source_field to the destination_field field. If the destination_field already exists, then the value of the source_field overwrites the original value of the destination_field.

move - Renames (moves) the source_field to the destination_field. If the destination_field already exists, then the value of the source_field overwrites the original value of the destination_field. Rename is identical to copy, except that the source_field is removed after the value has been copied to the destination_field (it is the same as a copy followed by a remove).

merge - Merges the value of the source_field with the value of the destination_field. The destination_field is converted into an array if it is not already an array, and the value of the source_field is appended to the array. This operation removes the source_field after the merge. If the source_field does not exist in the current document, then the destination_field is still converted into an array (if it is not an array already). This conversion ensures the type for destination_field is consistent across all documents.

remove - Deletes the source_field field. The destination_field is ignored for this operation.

remove_nulls - Removes all nested null (blank) field values from the ingested document. source_field and destination_field are ignored by this operation because remove_nulls operates on the entire ingested document. Typically, remove_nulls is invoked as the last normalization operation (if it is invoked at all, it can be time-expensive).