From 91958f623b194a19fa50d18958b24d73726ba488 Mon Sep 17 00:00:00 2001
From: Dan Larkin-York <dan.larkin-york@mongodb.com>
Date: Tue, 7 Mar 2023 17:20:55 +0000
Subject: SERVER-74631 Log index spec when validation detects index key
 inconsistencies

(cherry picked from commit 354b3b2ff1a72bef452b0037a707ecdc6879bff1)
---
 jstests/noPassthrough/validate_memory_limit.js |  7 +++++++
 src/mongo/db/catalog/collection_validation.cpp | 15 +++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/jstests/noPassthrough/validate_memory_limit.js b/jstests/noPassthrough/validate_memory_limit.js
index 5a576743177..63f55a0ed43 100644
--- a/jstests/noPassthrough/validate_memory_limit.js
+++ b/jstests/noPassthrough/validate_memory_limit.js
@@ -37,6 +37,11 @@ function checkValidate(maxMemoryUsage, {minMissingKeys, maxMissingKeys}) {
     assert.lte(res.missingIndexEntries.length, maxMissingKeys, tojson(res));
 }
 
+function checkValidateLogs() {
+    assert(checkLog.checkContainsWithAtLeastCountJson(
+        conn, 7463100, {"spec": {"v": 2, "key": {"_id": 1}, "name": "_id_"}}, 1));
+}
+
 function checkValidateRepair() {
     const res = coll.validate({repair: true});
     assert.commandWorked(res);
@@ -50,6 +55,7 @@ const indexKey = "a".repeat(kIndexKeyLength);
 assert.commandWorked(coll.insert({_id: indexKey}));
 corruptIndex();
 checkValidate(1, {minMissingKeys: 1, maxMissingKeys: 1});
+checkValidateLogs();
 
 // Can't repair successfully if there aren't any index inconsistencies reported.
 checkValidateRepair();
@@ -69,6 +75,7 @@ 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();
 
 // Repair, but incompletely if only some inconsistencies are reported.
 checkValidateRepair();
diff --git a/src/mongo/db/catalog/collection_validation.cpp b/src/mongo/db/catalog/collection_validation.cpp
index 31ee797b02c..517c18aaeaf 100644
--- a/src/mongo/db/catalog/collection_validation.cpp
+++ b/src/mongo/db/catalog/collection_validation.cpp
@@ -242,6 +242,20 @@ 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,
                               ValidateResults* results,
@@ -262,6 +276,7 @@ void _reportValidationResults(OperationContext* opCtx,
     for (const auto& [indexName, vr] : results->indexResultsMap) {
         if (!vr.valid) {
             results->valid = false;
+            _printIndexSpec(validateState, indexName);
         }
 
         if (validateState->getSkippedIndexes().contains(indexName)) {
-- 
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