[jira] [Commented] (DRILL-4021) Cannot subract or add between two timestamps

["Julian Hyde (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DRILL-4021?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14988403#comment-14988403 ] 

Julian Hyde commented on DRILL-4021:
------------------------------------

I'll ask a rhetorical question: If you subtract two timestamps, what units would you expect the result to have? Milliseconds? Days?

Standard SQL says that if you subtract two date-time values you need to say what type of interval you can back (e.g. an interval in seconds). Thus you must write {code}t2 - t1 second{code} or {code}t2 - t1 month to year{code}.

Standard SQL does not allow you add two date-time values at all. What would you expect 2015-01-01 + 2015-01-01 to return? I suppose you could say 'a value twice as far from the 1970-01-01 epoch as 2015-01-01' but then you are assuming an epoch.

If you want to add to a date-time value, add an interval. {code}date '2015-01-01' + interval '2' year{code} should work.

So, this is not a bug.

> Cannot subract or add between two timestamps
> --------------------------------------------
>
>                 Key: DRILL-4021
>                 URL: https://issues.apache.org/jira/browse/DRILL-4021
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Execution - Data Types
>            Reporter: Krystal
>
> The following subtraction between 2 now() function works:
> select now() - now()from voter_hive limit 1;
> +---------+
> | EXPR$0  |
> +---------+
> | PT0S    |
> +---------+
>  
> However, the following queries fail:
> select now() - create_time from voter_hive where voter_id=1;
> Error: VALIDATION ERROR: From line 1, column 8 to line 1, column 26: Cannot apply '-' to arguments of type '<ANY> - <TIMESTAMP(0)>'. Supported form(s): '<NUMERIC> - <NUMERIC>'
> '<DATETIME_INTERVAL> - <DATETIME_INTERVAL>'
> '<DATETIME> - <DATETIME_INTERVAL>'
> select create_time - cast('1997-02-12 15:18:31.072' as timestamp) from voter_hive where voter_id=1;
> Error: VALIDATION ERROR: From line 1, column 8 to line 1, column 65: Cannot apply '-' to arguments of type '<TIMESTAMP(0)> - <TIMESTAMP(0)>'. Supported form(s): '<NUMERIC> - <NUMERIC>'
> '<DATETIME_INTERVAL> - <DATETIME_INTERVAL>'
> '<DATETIME> - <DATETIME_INTERVAL>'



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