[jira] [Created] (DRILL-3432) Change or document: CAST to interval type doesn't reject non-standard strings

["Daniel Barclay (Drill) (JIRA)" <ji...@apache.org>]

Daniel Barclay (Drill) created DRILL-3432:
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             Summary: Change or document: CAST to interval type doesn't reject non-standard strings
                 Key: DRILL-3432
                 URL: https://issues.apache.org/jira/browse/DRILL-3432
             Project: Apache Drill
          Issue Type: Bug
            Reporter: Daniel Barclay (Drill)


In ISO/IEC 9075-2:2011(E) section 6.13 <cast specification>, General Rule 19 case b says that, in a <cast specification> casting to an interval type, a character string value must be a valid interval <literal> (<interval literal>) or <unquoted interval string>, or else a "data exception — invalid interval format" exception is raised.

(<interval literal> is the "{{INTERVAL '1-6' YEAR TO MONTH}}" syntax; <unquoted interval string> is the "{{1-6}}" syntax.)

However, in Drill, a cast specification casting to an interval type accepts strings not allowed by the SQL standard (ISO-8601 durations, e.g., "{{P1Y6M"}}).
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Drill should either follow the SQL standard or document the non-standard behavior in the end-user documentation.
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(Note that Drill's current behavior is not quite an extension:  Although it does extend the set of strings that can be converted, it lacks the rejection of non-standard strings (for, say, validating strings destined for input into a standard-SQL system).)

To continue providing the ability to convert ISO-8601-format duration strings into interval values without being non-compliant with the SQL standard, Drill could provide the conversions in conversion functions (perhaps CONVERT_FROM and/or CONVERT_TO).




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