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Posted to issues@calcite.apache.org by "Stamatis Zampetakis (Jira)" <ji...@apache.org> on 2020/09/01 08:31:00 UTC
[jira] [Commented] (CALCITE-4160) Add configuration to retain ORDER
BY in sub-query
[ https://issues.apache.org/jira/browse/CALCITE-4160?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17188261#comment-17188261 ]
Stamatis Zampetakis commented on CALCITE-4160:
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The SQL standard classifies the following in the list of optional features:
|F850| Top-level <order by clause> in <query expression>|
|F851| <order by clause> in subqueries|
|F852| Top-level <order by clause> in views|
|F855| Nested <order by clause> in <query expression>|
That is to say that ORDER BY in subqueries is something covered by the SQL standard. Moreover it is worth noting that even top-level ORDER BY
expressions belong to the list of optional features.
Below some relevant extracts from the SQL standard:
Without Feature F850, “Top-level <order by clause>in <query expression>”, in conforming SQL language,
a <query expression> not immediately contained in either an <array value constructor by query> or a
<cursor specification> shall not immediately contain an <order by clause>.
Without Feature F851, “<order by clause>in subqueries”, in conforming SQL language, a <query expression>
contained in another <query expression> shall not immediately contain an <order by clause>.
Without Feature F852, “Top-level <order by clause>in views”, in conforming SQL language, a <query
expression> immediately contained in a <view definition> shall not immediately contain an <order by
clause>.
Without Feature F855, “Nested <order by clause>in <query expression>”, in conforming SQL language,
a <query primary> shall not immediately contain an <order by clause>.
> Add configuration to retain ORDER BY in sub-query
> -------------------------------------------------
>
> Key: CALCITE-4160
> URL: https://issues.apache.org/jira/browse/CALCITE-4160
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Jiatao Tao
> Assignee: Jiatao Tao
> Priority: Minor
> Labels: pull-request-available
> Attachments: image-2020-08-07-10-48-59-599.png, image-2020-08-07-10-50-22-351.png
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Pre discussion see in
> https://issues.apache.org/jira/browse/CALCITE-2798
> https://issues.apache.org/jira/browse/CALCITE-3664
> IMO, we should at least provide a configuration about this. People use Calcite most for its optimizer, and this info users may care, How it executed is by the engine, but users should know this in the plan.
>
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