[jira] [Comment Edited] (CALCITE-482) Implement SQL and planner hints

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

    [ https://issues.apache.org/jira/browse/CALCITE-482?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17014287#comment-17014287 ] 

Vladimir Sitnikov edited comment on CALCITE-482 at 1/13/20 12:45 PM:
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What I mean is CALCITE-482 created an inconsistency in the API.

Previously there were two arguments: transformTo(RelNode rel, Map<RelNode, RelNode> equiv), and both arguments (RelNode and Map) were consistent. RelNode argument was just like a shortcut for the case when only a single equivalence needs to be registered.

Now you add {{BiFunction<RelNode, RelNode, RelNode> handler}} function that applies to one of the arguments only, and it completely ignores {{Map<RelNode, RelNode>}}

That does not sound right.

Re BiFunction. Have you considered creating a named interface to express the meaning of the parameter?
Frankly speaking, {{BiFunction<RelNode, RelNode, RelNode> handler}} is really confusing (both interface naming and parameter naming).


was (Author: vladimirsitnikov):
What I mean is CALCITE-482 created an inconsistency in the API.

Previously there were two arguments: transformTo(RelNode rel, Map<RelNode, RelNode> equiv), and both arguments (RelNode and Map) were consistent. RelNode argument was just like a shortcut for the case when only a single equivalence needs to be registered.

Now you add {{BiFunction<RelNode, RelNode, RelNode> handler}} function that applies to one of the arguments only, and it completely ignores {{Map<RelNode, RelNode>}}

That does not sound right.

Re BiFunction. Have you considered to create a named interface to express the meaning of the parameter?
Frankly speaking, {{BiFunction<RelNode, RelNode, RelNode> handler}} is really confusing (both interface naming and parameter naming).


> Implement SQL and planner hints
> -------------------------------
>
>                 Key: CALCITE-482
>                 URL: https://issues.apache.org/jira/browse/CALCITE-482
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.21.0
>            Reporter: Vladimir Sitnikov
>            Assignee: Danny Chen
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.22.0
>
>          Time Spent: 8h 10m
>  Remaining Estimate: 0h
>
> Query optimizer can never be perfect, so it makes sense to implement hints to allow user better control the execution.
> For instance: "never merge this subquery with others" (`/+ no_merge/`), "treat those tables as leading ones" (`/*+ leading */`), etc.
> Hints would enable predictable performance and the planning time would be improved as well.



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