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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-7821) Replace Table.limit() by Table.fetch() and Table.offset()
Date Tue, 24 Oct 2017 08:46:00 GMT

    [ https://issues.apache.org/jira/browse/FLINK-7821?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16216547#comment-16216547
] 

ASF GitHub Bot commented on FLINK-7821:
---------------------------------------

Github user twalthr commented on a diff in the pull request:

    https://github.com/apache/flink/pull/4813#discussion_r146490693
  
    --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/table.scala
---
    @@ -745,12 +748,65 @@ class Table(
         *
         * @param offset number of records to skip
         * @param fetch number of records to be returned
    +    *
    +    * @deprecated Please use [[Table.offset()]] and [[Table.fetch()]] instead.
         */
    +  @deprecated(message = "deprecated in favor of Table.offset() and Table.fetch()", since
= "1.4.0")
       def limit(offset: Int, fetch: Int): Table = {
         new Table(tableEnv, Limit(offset, fetch, logicalPlan).validate(tableEnv))
       }
     
       /**
    +    * Limits a sorted result from an offset position.
    +    * Similar to a SQL OFFSET clause. Offset is technically part of the Order By operator
and
    +    * thus must be preceded by it.
    +    *
    +    * [[Table.offset(o)]] can be combined with a subsequent [[Table.fetch(n)]] call to
return the
    +    * first n rows starting from the offset position o.
    --- End diff --
    
    Maybe you can add a notice about the SQL indices here, as it might confuses users. Or
you add `skips 3 rows and begins with the 4th record`.


> Replace Table.limit() by Table.fetch() and Table.offset()
> ---------------------------------------------------------
>
>                 Key: FLINK-7821
>                 URL: https://issues.apache.org/jira/browse/FLINK-7821
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>    Affects Versions: 1.4.0
>            Reporter: Fabian Hueske
>            Assignee: Fabian Hueske
>            Priority: Minor
>
> The Table API method limit() exists in two variants:
> - {{limit(offset)}} returns all but the first {{offset}} records.
> - {{limit(offset, fetch)}} returns {{fetch}} records starting from the {{offset}}'s record.
> Especially, the behavior of {{limit(offset)}} is confusing because one would rather expect
a behavior of returning the {{offset}} first records instead of all but the {{offset}} first
records.
> Moreover, the only way to return the first {{x}} records is to specify a {{0}} offset
as {{limit(0, x)}}.
> I propose to deprecate and replace both {{limit()}} variants by two new methods {{Table.offset(offset)}}
and {{Table.fetch(fetch)}} that can be combined as follows:
> {code}
> table.orderBy(...).fetch(x)
> table.orderBy(...).offset(x)
> table.orderBy(...).offset(x).fetch(y)
> {code}



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