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The following commit(s) were added to refs/heads/master by this push: new df5f447 [CALCITE-3981] Volcano.register should not return stale subset (Botong Huang) df5f447 is described below commit df5f4470e4257e8e7057664d4af3af3f37b6559b Author: botong.huang <botong.hu...@alibaba-inc.com> AuthorDate: Sat Apr 18 22:15:30 2020 -0700 [CALCITE-3981] Volcano.register should not return stale subset (Botong Huang) When a subset is registered, registerImpl() and registerSubset() currently simply returns the subset itself. The problem is that subset can become stale when relSets get merged (for example in ensureRegistered() and registerSubset() "merge(set, subset.set)"). As a result, a stale subset might be returned from registerImpl, and the newly registering subtree might get registered recursively on top of the stale subset (see AbstractRelNode.onRegister()). This is a leak because once a relSet is merged into others and becomes stale, it should not be used to connect new relNodes. With CALCITE-3755, subsets can now be directly matched by rules. This opens another source of stale subset leak: (1) An active subset gets matched, the RuleMatch gets queued in RuleQueue. (2) The subset becomes stale due to relSet merge. (3) The rule match in (1) is popped from queue and fired. (4) In OnMatch the rule gets the stale subset, builds new rels on top of it and regsiter the new rels. In this case, the entire new rel subtree will be registered on top of the stale subset as is. Close #1966 --- .../main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java b/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java index 90030d0..d7dcd5f 100644 --- a/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java +++ b/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java @@ -628,6 +628,7 @@ public class VolcanoPlanner extends AbstractRelOptPlanner { "equivRel rowtype", equivRel.getRowType(), Litmus.THROW); + equivRel = ensureRegistered(equivRel, null); set = getSet(equivRel); } return registerImpl(rel, set); @@ -643,7 +644,7 @@ public class VolcanoPlanner extends AbstractRelOptPlanner { merge(equivSubset.set, subset.set); } } - result = subset; + result = canonize(subset); } else { result = register(rel, equivRel); } @@ -1024,7 +1025,7 @@ public class VolcanoPlanner extends AbstractRelOptPlanner { set = set.equivalentSet; } while (set.equivalentSet != null); return set.getOrCreateSubset( - subset.getCluster(), subset.getTraitSet()); + subset.getCluster(), subset.getTraitSet(), subset.isRequired()); } /** @@ -1331,7 +1332,7 @@ public class VolcanoPlanner extends AbstractRelOptPlanner { LOGGER.trace("Register #{} {}, and merge sets", subset.getId(), subset); merge(set, subset.set); } - return subset; + return canonize(subset); } // implement RelOptPlanner