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https://issues.apache.org/jira/browse/CALCITE-3972?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17101144#comment-17101144
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Xiening Dai commented on CALCITE-3972:
--------------------------------------
If convention is considered as part of the config, then it looks weird that
adoptConvention() preserves builder stack while
RelBuilder#transform(UnaryOperator<Config> transform) does not.
Furthermore, a common usage pattern like below won't work because the builder
object referenced by filter is not the one after adoptConvention() -
{code:java}
RelNode root =
builder.adoptConvention(EnumerableConvention.INSTANCE)
.scan("EMP")
.filter(
builder.equals(builder.field("DEPTNO"), builder.literal(20)))
.build();
{code}
In my view, if we'd like to support switching convention in the middle of
building nodes, we should treat convention as a mutable state - just like
stake. Or we abandon such capability, and don't preserve stake when switching
convention. In that case, we don't need adoptConvention(), modifying current
transform() should be enough.
> Allow RelBuilder to create RelNode with convention and use it for trait
> convert
> -------------------------------------------------------------------------------
>
> Key: CALCITE-3972
> URL: https://issues.apache.org/jira/browse/CALCITE-3972
> Project: Calcite
> Issue Type: Bug
> Reporter: Xiening Dai
> Assignee: Xiening Dai
> Priority: Major
> Fix For: 1.23.0
>
> Time Spent: 40m
> Remaining Estimate: 0h
>
> 1. Provide Convention.transformRelBuilder() to transform an existing
> RelBuilder into one with specific convention.
> 2. RelBuilder provides withRelFactories() method to allow caller swap the
> underlying RelFactories and create a new builder.
> 3. Use the new interface in RelCollationTraitDef for converting into
> RelCollation traits
> We can avoid ~1/3 of total rule firings in a N way join case with this change.
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