[
https://issues.apache.org/jira/browse/PHOENIX-1749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14487713#comment-14487713
]
Julian Hyde commented on PHOENIX-1749:
--------------------------------------
[~maryannxue] Yes, that is what collations do. You can also have equivalent
relational expressions (i.e. different expressions that produce the same
result) that are sorted and not sorted, and maybe the unsorted one is cheaper.
[~jamestaylor] You can define functions' monotonicity. SUBSTRING(string FROM 0
FOR n) is monotonic. CAST(number AS string) is not monotonic.
> ORDER BY should support ordinal position as well as expression
> --------------------------------------------------------------
>
> Key: PHOENIX-1749
> URL: https://issues.apache.org/jira/browse/PHOENIX-1749
> Project: Phoenix
> Issue Type: Bug
> Reporter: Serhiy Bilousov
> Assignee: Alicia Ying Shu
> Attachments: PHOENIX-1749-v1.patch, PHOENIX-1749.patch,
> Phoenix-1749-v2.patch
>
>
> In postgreSQL (and many others DBs) you can specify not only column name for
> the ORDER BY but column number (position in SELECT part) as well as column
> alias.
> see:
> http://www.postgresql.org/docs/9.4/static/queries-order.html
> http://www.postgresql.org/docs/9.4/static/sql-select.html#SQL-GROUPBY
> Adding such support would be very helpful and sometimes necessary.
> I can provide real queries example if required but basically we want
> something like this
> given query
> SELECT a, b, TRUNC(current_date(),'HOUR') AS date_truncated FROM table
> we want
> ORDER BY 1 ASC, 2 DESC
> ORDER BY date_truncated
> Having just column number would cover both but having column alias would make
> queries more readable and human friendly. Plus make it one little stem closer
> to postgreSQL and SQL standard.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
