1 files changed, 19 insertions, 14 deletions

diff --git a/src/mongo/db/query/plan_cache_indexability.cpp b/src/mongo/db/query/plan_cache_indexability.cpp
index 4846cd85778..216b714dbed 100644
--- a/src/mongo/db/query/plan_cache_indexability.cpp
+++ b/src/mongo/db/query/plan_cache_indexability.cpp
@@ -119,7 +119,7 @@ void PlanCacheIndexabilityState::processWildcardIndex(const CoreIndexInfo& cii)
     invariant(cii.type == IndexType::INDEX_WILDCARD);
 
     _wildcardIndexDiscriminators.emplace_back(
-        cii.wildcardProjection->exec(), cii.identifier.catalogName, cii.filterExpr, cii.collator);
+        cii.wildcardProjection->exec(), cii.identifier.catalogName, cii.collator);
 }
 
 void PlanCacheIndexabilityState::processIndexCollation(const std::string& indexName,
@@ -159,10 +159,6 @@ IndexToDiscriminatorMap PlanCacheIndexabilityState::buildWildcardDiscriminators(
             cid.addDiscriminator(QueryPlannerIXSelect::nodeIsSupportedByWildcardIndex);
             cid.addDiscriminator(nodeIsConservativelySupportedBySparseIndex);
             cid.addDiscriminator(getCollatedIndexDiscriminator(wildcardDiscriminator.collator));
-            if (wildcardDiscriminator.filterExpr) {
-                cid.addDiscriminator(
-                    getPartialIndexDiscriminator(wildcardDiscriminator.filterExpr));
-            }
         }
     }
     return ret;
@@ -174,19 +170,28 @@ void PlanCacheIndexabilityState::updateDiscriminators(
     _wildcardIndexDiscriminators.clear();
 
     for (const auto& idx : indexCores) {
-        if (idx.type == IndexType::INDEX_WILDCARD) {
-            processWildcardIndex(idx);
-            continue;
-        }
-
-        if (idx.sparse) {
-            processSparseIndex(idx.identifier.catalogName, idx.keyPattern);
-        }
+        // If necessary, add discriminators for the paths mentioned in the partial filter
+        // expression. Unlike most of the discriminator logic, this is shared for wildcard and
+        // non-wildcard indexes.
         if (idx.filterExpr) {
             processPartialIndex(idx.identifier.catalogName, idx.filterExpr);
         }
 
-        processIndexCollation(idx.identifier.catalogName, idx.keyPattern, idx.collator);
+        if (idx.type == IndexType::INDEX_WILDCARD) {
+            // The set of paths for which we should add disciminators for wildcard indexes (outside
+            // of those paths mentioned in the partial filter expression) is not known a priori.
+            // Instead, we just record some information about the wildcard index so that the
+            // discriminators can be constructed on demand at query runtime.
+            processWildcardIndex(idx);
+        } else {
+            // If the index is not wildcard, add discriminators for fields mentioned in the key
+            // pattern.
+            if (idx.sparse) {
+                processSparseIndex(idx.identifier.catalogName, idx.keyPattern);
+            }
+
+            processIndexCollation(idx.identifier.catalogName, idx.keyPattern, idx.collator);
+        }
     }
 }