[jira] [Comment Edited] (CALCITE-2798) Optimizer should remove unneeded Sort

["Vladimir Sitnikov (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-2798?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16750443#comment-16750443 ] 

Vladimir Sitnikov edited comment on CALCITE-2798 at 1/23/19 9:24 PM:
---------------------------------------------------------------------

{quote}I know you have written elsewhere that you think that LogicalWindow should preserve sort order. So we have philosophical differences on this one.{quote}
By the way: what's your take on {{LogicalProject(expr1=row_number() over (partition by x order by y))}} ? Should this project keep the order of input rows?


was (Author: vladimirsitnikov):
{quote}I know you have written elsewhere that you think that LogicalWindow should preserve sort order. So we have philosophical differences on this one.{quote}
By the way: what's your take on {{LogicalProject(expr1=row_number() over (partition by x order by y))}} should this project keep the order of input rows?

> Optimizer should remove unneeded Sort
> -------------------------------------
>
>                 Key: CALCITE-2798
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2798
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.18.0
>            Reporter: Vladimir Sitnikov
>            Assignee: Julian Hyde
>            Priority: Major
>
> The following SQL performs sort twice, however inner sort can be eliminated
> {code}select * from (
>   select * from "emps" 
> order by "emps"."deptno"
> ) order by 1 desc{code}
> The same goes for (window calculation will sort on its own)
> {code}select row_number() over (order by "emps"."deptno")  from (
>   select * from "emps" 
> order by "emps"."deptno" desc
> ){code}
> The same goes for SetOp (union, minus):
> {code}select * from (
>   select * from "emps" 
> order by "emps"."deptno"
> ) union select * from (
>   select * from "emps" 
> order by "emps"."deptno" desc
> ){code}
> There might be other cases like that (e.g. Aggregate, Join, Exchange, SortExchange)



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)