jackwener commented on code in PR #4618:
URL: https://github.com/apache/arrow-datafusion/pull/4618#discussion_r1048587713
##########
datafusion/optimizer/src/eliminate_limit.rs:
##########
@@ -40,37 +42,59 @@ impl OptimizerRule for EliminateLimit {
fn optimize(
&self,
plan: &LogicalPlan,
- optimizer_config: &mut OptimizerConfig,
+ _optimizer_config: &mut OptimizerConfig,
) -> Result<LogicalPlan> {
- if let LogicalPlan::Limit(limit) = plan {
- match limit.fetch {
- Some(fetch) => {
- if fetch == 0 {
- return Ok(LogicalPlan::EmptyRelation(EmptyRelation {
- produce_one_row: false,
- schema: limit.input.schema().clone(),
- }));
- }
+ Ok(self
+ .try_optimize(plan, _optimizer_config)?
+ .unwrap_or_else(|| plan.clone()))
+ }
+
+ fn try_optimize(
+ &self,
+ plan: &LogicalPlan,
+ _optimizer_config: &mut OptimizerConfig,
+ ) -> Result<Option<LogicalPlan>> {
+ let limit = match plan {
+ LogicalPlan::Limit(limit) => limit,
+ _ => return Ok(None),
+ };
+
+ match limit.fetch {
+ Some(fetch) => {
+ if fetch == 0 {
+ return Ok(Some(LogicalPlan::EmptyRelation(EmptyRelation {
+ produce_one_row: false,
+ schema: limit.input.schema().clone(),
+ })));
}
- None => {
- if limit.skip == 0 {
- let input = &*limit.input;
- return utils::optimize_children(self, input,
optimizer_config);
- }
+ }
+ None => {
+ if limit.skip == 0 {
+ let input = limit.input.as_ref();
+ // input also can be Limit, so we should apply again.
+ return Ok(Some(
+ self.try_optimize(input, _optimizer_config)?
+ .unwrap_or_else(|| input.clone()),
+ ));
Review Comment:
🎉we don't need to recurse optimize children inside rule.
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