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https://issues.apache.org/jira/browse/CALCITE-506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14240103#comment-14240103
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Vladimir Sitnikov commented on CALCITE-506:
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{quote} We don't expect the public to build classes that implement
EnumerableRel outside of the Calcite code base.{quote}
We do expect public to _use_ that class, don't we?
1) How would you implement {{MongoToEnumerableConverter}} without
{{EnumerableRelImplementor}}?
2) It is much easier to stick with enumerable convention unless you want to
implement executor from scratch. I mean there
{quote}[~vladimirsitnikov]I think the ability to "pass non-string literals to
EnumerableImplementor" is quote often requested.{quote}
Any hints on the preferred approach here?
Well, "the proper way" might be to go through {{RexBuilder.makeLiteral}}. For
instance, allow to invoke {{makeLiteral(customObject, SqlTypeName,OTHER, ...)}}
for user-defined data types.
So the end-to-end would be:
1) User passes random java object into the query via
{{RexBuilder#makeLiteral(customObject, SqlTypeName,OTHER}}
2) EnumerableImplementor detects such OTHER literals and passes it via
DataContext transparently to the user.
Would this qualify as proper usage of OTHER sql type?
> Update EnumerableRelImplementor.stash so it is suitable for all kinds of
> classes
> --------------------------------------------------------------------------------
>
> Key: CALCITE-506
> URL: https://issues.apache.org/jira/browse/CALCITE-506
> Project: Calcite
> Issue Type: Bug
> Affects Versions: 1.0.0-incubating
> Reporter: Vladimir Sitnikov
> Assignee: Julian Hyde
> Labels: newbie
>
> {code:java}
> public Expression stash(RelNode child, Class clazz) {
> final ParameterExpression x = register(child, clazz);
> final Expression e = Expressions.call(getRootExpression(),
> BuiltInMethod.DATA_CONTEXT_GET.method, Expressions.constant(x.name));
> return Expressions.convert_(e, clazz);
> }
> {code}
> I would like to make two corrections here:
> 1) I think {{public <T> Expression st(T x, Class<? super T> clazz) \{}}
> should be better signature.
> 2) It makes sense to translate {{DATA_CONTEXT_GET}} as a store to a {{final}}
> local variable at the very start of {{public
> org.apache.calcite.linq4j.Enumerable bind(final
> org.apache.calcite.DataContext root0)}} method (see {{implementRoot}}), so at
> the usage time it is just a load of local variable, not a {{map.get}}
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