The ML Engine does not preserve case when storing identifiers. For example, 'mixedCaseIdentifier' is stored as 'mixedcaseidentifier'. Therefore, when creating tables to input to the ML Engine functions, or specifying names for output columns, give columns names that use only lowercase letters, digits, and underscore (_).
If column names in an existing table have uppercase letters or special characters other than underscore, give those columns aliases that use only lowercase letters, digits, and underscore (_), and use the aliases in the function arguments. For example:
SELECT * FROM DWT ( ON (SELECT city, period, temp_F AS temp_f, pressure_mbar, dewpoint_F AS dewpoint_f FROM ville_climatedata ) AS InputTable PARTITION BY 1 OUT TABLE OutputTable (dwt_coef_table) OUT TABLE MetaTable (dwt_meta_table) USING TargetColumns ('temp_f','pressure_mbar','dewpoint_f') SortColumn ('period') PartitionColumns ('city') Wavelet ('db2') WaveletTransformLevel (2) ) AS dwtout;