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https://issues.apache.org/jira/browse/FLINK-7821?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16201666#comment-16201666
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ASF GitHub Bot commented on FLINK-7821:
---------------------------------------
GitHub user fhueske opened a pull request:
https://github.com/apache/flink/pull/4813
[FLINK-7821] [table] Deprecate Table.limit() and replace it by
Table.offset() and Table.fetch().
## What is the purpose of the change
- `Table.limit(n)` has unexpected semantics of returning all but the first
`n` rows.
- Returning the first `n` rows from a sorted result requires to specify a 0
offset (`table.orderBy(...).limit(0, n)`) which is more complicated than
necessary.
## Brief change log
- deprecate `Table.limit()` and replace it by `Table.offset()` and
`Table.fetch()`
## Verifying this change
- existing tests for `limit` were adapted for `offset` and `fetch`.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): **no**
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: **no**
- The serializers: **no**
- The runtime per-record code paths (performance sensitive): **no**
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: **no**
## Documentation
- Documentation was adapted.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/fhueske/flink tableOffsetFetch
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/4813.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #4813
----
commit 7b1e3cb03a8e863699940b152f727551c2d43ea0
Author: Fabian Hueske <fhue...@apache.org>
Date: 2017-10-12T08:56:19Z
[FLINK-7821] [table] Deprecate Table.limit() and replace it by
Table.offset() and Table.fetch().
----
> 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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