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https://issues.apache.org/jira/browse/CALCITE-5456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17652101#comment-17652101
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grandfisher commented on CALCITE-5456:
--------------------------------------
I found the reason for this issue is that myTableScan doesn't overridden
`withHints` method.
The default implementation return Relnode self directly.
{code:java}
// Hintable#withHints
default RelNode withHints(List<RelHint> hintList) {
return (RelNode) this;
} {code}
> Hints on Tablescan will lost when plannerImpl execute flattenTypes
> -------------------------------------------------------------------
>
> Key: CALCITE-5456
> URL: https://issues.apache.org/jira/browse/CALCITE-5456
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.32.0
> Reporter: grandfisher
> Priority: Major
>
> I want to use some hints on tablescan for extra processing. But hints wll
> lost after `flattenTypes`
> In PlannerImpl#rel(SqlNode sql)
> {code:java}
> // if hint apply on tablescan here
> RelRoot root =
> sqlToRelConverter.convertQuery(validatedSqlNode, false, true);
> // flattenTypes will make hints on tablescan lost
> root = root.withRel(sqlToRelConverter.flattenTypes(root.rel, true));{code}
> This is due to `RelStructuredTypeFlattener` use `ImmutableList.of()` to
> initialize context, and `RelStructuredTypeFlattener` recreate a new
> `tablescan` relnode with this context
> {code:java}
> // PlannerImpl#flattenTypes
> public RelNode flattenTypes(
> RelNode rootRel,
> boolean restructure) {
> RelStructuredTypeFlattener typeFlattener =
> new RelStructuredTypeFlattener(relBuilder,
> rexBuilder, createToRelContext(ImmutableList.of()), restructure);
> return typeFlattener.rewrite(rootRel);
> } {code}
> {code:java}
> // RelStructuredTypeFlattener#rewriteRel
> public void rewriteRel(TableScan rel) {
> RelNode newRel = rel.getTable().toRel(toRelContext);
> if (!SqlTypeUtil.isFlat(rel.getRowType())) {
> newRel = coverNewRelByFlatteningProjection(rel, newRel);
> }
> setNewForOldRel(rel, newRel);
> } {code}
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