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fix(optimizer): Fix infinite loop in UnaliasSymbolReferences.canonicalize() #27428

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Merged
feilong-liu merged 1 commit into from
Mar 25, 2026
Merged

fix(optimizer): Fix infinite loop in UnaliasSymbolReferences.canonicalize() #27428

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8 changes: 8 additions & 0 deletions .../src/main/java/com/facebook/presto/sql/planner/optimizations/UnaliasSymbolReferences.java
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Original file line number Diff line number Diff line change
Expand Up @@ -887,8 +887,16 @@ else if (determinismEvaluator.isDeterministic(expression)) {
private VariableReferenceExpression canonicalize(VariableReferenceExpression variable)
{
String canonical = variable.getName();
Set<String> visited = new HashSet<>();
visited.add(canonical);
while (mapping.containsKey(canonical)) {
canonical = mapping.get(canonical);
if (!visited.add(canonical)) {
// Cycle detected in alias mapping; break the cycle by removing the mapping entry
// that would close the loop and stop at the current canonical name.
mapping.remove(canonical);
break;
}
}
return new VariableReferenceExpression(variable.getSourceLocation(), canonical, types.get(new SymbolReference(getNodeLocation(variable.getSourceLocation()), canonical)));
}
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