[
https://issues.apache.org/jira/browse/CALCITE-7227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18029915#comment-18029915
]
Julian Hyde commented on CALCITE-7227:
--------------------------------------
{{StandardConvertletTable}} is an implementation of {{interface
SqlRexConvertletTable}}. Is there any reason why you couldn't produce another
implementation?
It would be useful to re-imagine {{StandardConvertletTable}}. Originally
{{StandardConvertletTable}} was a useful container of desugaring mappings. But
not everyone wants to apply those mappings (the example you cite, {{SQRT\(x)}}
→ {{POW(x, .5)}} is a great example). Some people might even want to apply
the mappings in the other direction ({{NVL}} → {{COALESCE}}) or
({{COALESCE}} → {{NVL}}).
The way to do this, I think, is to create concept of a "Rex rule" that is
analogous to RelRule but works on scalar expressions (and also aggregate
functions).
> There is no way to modify the StandardConvertletTable
> -----------------------------------------------------
>
> Key: CALCITE-7227
> URL: https://issues.apache.org/jira/browse/CALCITE-7227
> Project: Calcite
> Issue Type: Wish
> Components: core
> Affects Versions: 1.40.0
> Reporter: Mihai Budiu
> Priority: Minor
>
> The convertlet table has a lot of functionality, but there is no easy way to,
> let's say, exclude one of the conversions that is undesirable. Copying and
> modifying the whole class is a solution, but it is not great. Adding new
> conversions seems possible, but excluding the existing ones seems impossible.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
