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

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

    [ https://issues.apache.org/jira/browse/DRILL-3432?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14608982#comment-14608982 ] 

Daniel Barclay (Drill) commented on DRILL-3432:
-----------------------------------------------

(Supersedes only corresponding part of DRILL-2864.)

> 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"}}).
> &nbsp;
> Drill should either follow the SQL standard or document the non-standard behavior in the end-user documentation.
> &nbsp;
> (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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