SERVER-74631 Log index spec when validation detects index key inconsistencies

(cherry picked from commit 354b3b2ff1a72bef452b0037a707ecdc6879bff1)

2 files changed, 22 insertions, 0 deletions

diff --git a/jstests/noPassthrough/validate_memory_limit.js b/jstests/noPassthrough/validate_memory_limit.js
index f229d2848c8..40dbdd36626 100644
--- a/jstests/noPassthrough/validate_memory_limit.js
+++ b/jstests/noPassthrough/validate_memory_limit.js
@@ -34,12 +34,18 @@ function checkValidate(maxMemoryUsage, {minMissingKeys, maxMissingKeys}) {
     assert.lte(res.missingIndexEntries.length, maxMissingKeys, tojson(res));
 }
 
+function checkValidateLogs() {
+    assert(checkLog.checkContainsOnceJson(
+        conn, 7463100, {"spec": {"v": 2, "key": {"_id": 1}, "name": "_id_"}}));
+}
+
 // Insert a document with a key larger than maxValidateMemoryUsageMB and test that we still report
 // at least one inconsistency.
 const indexKey = "a".repeat(kIndexKeyLength);
 assert.commandWorked(coll.insert({_id: indexKey}));
 corruptIndex();
 checkValidate(1, {minMissingKeys: 1, maxMissingKeys: 1});
+checkValidateLogs();
 
 // Clear collection between tests.
 coll.drop();
@@ -56,6 +62,7 @@ corruptIndex();
 // each key is counted twice, so realistically we only expect to track 2 of them. However, there's
 // a small chance we could get hash collisions that would lead to us reporting only 1.
 checkValidate(1, {minMissingKeys: 1, maxMissingKeys: 2});
+checkValidateLogs();
 
 MongoRunner.stopMongod(conn, null, {skipValidation: true});
 })();
\ No newline at end of file
diff --git a/src/mongo/db/catalog/collection_validation.cpp b/src/mongo/db/catalog/collection_validation.cpp
index 0eaa4992ad6..81c92a4f46e 100644
--- a/src/mongo/db/catalog/collection_validation.cpp
+++ b/src/mongo/db/catalog/collection_validation.cpp
@@ -248,6 +248,20 @@ void _validateIndexKeyCount(OperationContext* opCtx,
     }
 }
 
+void _printIndexSpec(const ValidateState* validateState, StringData indexName) {
+    auto& indexes = validateState->getIndexes();
+    auto indexEntry =
+        std::find_if(indexes.begin(),
+                     indexes.end(),
+                     [&](const std::shared_ptr<const IndexCatalogEntry> indexEntry) -> bool {
+                         return indexEntry->descriptor()->indexName() == indexName;
+                     });
+    if (indexEntry != indexes.end()) {
+        auto indexSpec = (*indexEntry)->descriptor()->infoObj();
+        LOGV2_ERROR(7463100, "Index failed validation", "spec"_attr = indexSpec);
+    }
+}
+
 void _reportValidationResults(OperationContext* opCtx,
                               ValidateState* validateState,
                               ValidateResultsMap* indexNsResultsMap,
@@ -268,6 +282,7 @@ void _reportValidationResults(OperationContext* opCtx,
     for (const auto& [indexName, vr] : *indexNsResultsMap) {
         if (!vr.valid) {
             results->valid = false;
+            _printIndexSpec(validateState, indexName);
         }
 
         if (validateState->getSkippedIndexes().contains(indexName)) {