SERVER-73365 Skip double rebuild during path lowering

2 files changed, 12 insertions, 8 deletions

diff --git a/src/mongo/db/query/optimizer/rewrites/path_lower.cpp b/src/mongo/db/query/optimizer/rewrites/path_lower.cpp
index ba906daa40b..6fcd8f273c3 100644
--- a/src/mongo/db/query/optimizer/rewrites/path_lower.cpp
+++ b/src/mongo/db/query/optimizer/rewrites/path_lower.cpp
@@ -31,7 +31,7 @@
 
 
 namespace mongo::optimizer {
-bool EvalPathLowering::optimize(ABT& n) {
+bool EvalPathLowering::optimize(ABT& n, bool rebuild) {
     _changed = false;
 
     algebra::transport<true>(n, *this);
@@ -39,7 +39,7 @@ bool EvalPathLowering::optimize(ABT& n) {
     // This is needed for cases in which EvalPathLowering is called from a context other than during
     // PathLowering. If the ABT is modified in a way that adds variable references and definitions
     // the environment must be updated.
-    if (_changed) {
+    if (_changed && rebuild) {
         _env.rebuild(n);
     }
 
@@ -223,7 +223,7 @@ void EvalPathLowering::transport(ABT& n, const EvalPath&, ABT& path, ABT& input)
     _changed = true;
 }
 
-bool EvalFilterLowering::optimize(ABT& n) {
+bool EvalFilterLowering::optimize(ABT& n, bool rebuild) {
     _changed = false;
 
     algebra::transport<true>(n, *this);
@@ -231,7 +231,7 @@ bool EvalFilterLowering::optimize(ABT& n) {
     // This is needed for cases in which EvalFilterLowering is called from a context other than
     // during PathLowering. If the ABT is modified in a way that adds variable references or
     // definitions the environment must be updated.
-    if (_changed) {
+    if (_changed && rebuild) {
         _env.rebuild(n);
     }
 
@@ -414,11 +414,11 @@ void EvalFilterLowering::transport(ABT& n, const EvalFilter&, ABT& path, ABT& in
 }
 
 void PathLowering::transport(ABT& n, const EvalPath&, ABT&, ABT&) {
-    _changed = _changed || _project.optimize(n);
+    _changed = _changed || _project.optimize(n, false /*rebuild*/);
 }
 
 void PathLowering::transport(ABT& n, const EvalFilter&, ABT&, ABT&) {
-    _changed = _changed || _filter.optimize(n);
+    _changed = _changed || _filter.optimize(n, false /*rebuild*/);
 }
 
 bool PathLowering::optimize(ABT& n) {
diff --git a/src/mongo/db/query/optimizer/rewrites/path_lower.h b/src/mongo/db/query/optimizer/rewrites/path_lower.h
index 59df0f50050..6d156f60cbf 100644
--- a/src/mongo/db/query/optimizer/rewrites/path_lower.h
+++ b/src/mongo/db/query/optimizer/rewrites/path_lower.h
@@ -71,7 +71,9 @@ public:
 
     // The tree is passed in as NON-const reference as we will be updating it.
     // Returns true if the tree changed.
-    bool optimize(ABT& n);
+    // If 'rebuild' is set to false will assume the caller will rebuild the VariableEnvironment and
+    // so will skip the rebuild on the passed in ABT.
+    bool optimize(ABT& n, bool rebuild = true);
 
 private:
     // We don't own these.
@@ -119,7 +121,9 @@ public:
 
     // The tree is passed in as NON-const reference as we will be updating it.
     // Returns true if the tree changed.
-    bool optimize(ABT& n);
+    // If 'rebuild' is set to false will assume the caller will rebuild the VariableEnvironment and
+    // so will skip the rebuild on the passed in ABT.
+    bool optimize(ABT& n, bool rebuild = true);
 
 private:
     // We don't own these.