SERVER-57057 Reduce routing info refreshes on the mergeChunks path (BACKPORT-9358)

4 files changed, 36 insertions, 8 deletions

diff --git a/src/mongo/db/s/merge_chunks_command.cpp b/src/mongo/db/s/merge_chunks_command.cpp
index 0853213a910..615b2bdac9d 100644
--- a/src/mongo/db/s/merge_chunks_command.cpp
+++ b/src/mongo/db/s/merge_chunks_command.cpp
@@ -40,6 +40,7 @@
 #include "mongo/db/logical_clock.h"
 #include "mongo/db/namespace_string.h"
 #include "mongo/db/s/collection_sharding_state.h"
+#include "mongo/db/s/operation_sharding_state.h"
 #include "mongo/db/s/shard_filtering_metadata_refresh.h"
 #include "mongo/db/s/sharding_state.h"
 #include "mongo/logv2/log.h"
@@ -92,11 +93,19 @@ void mergeChunks(OperationContext* opCtx,
 
     // We now have the collection distributed lock, refresh metadata to latest version and sanity
     // check
-    forceShardFilteringMetadataRefresh(opCtx, nss, true /* forceRefreshFromThisThread */);
+    const bool isVersioned = OperationShardingState::isOperationVersioned(opCtx);
+    if (!isVersioned) {
+        forceShardFilteringMetadataRefresh(opCtx, nss, true /* forceRefreshFromThisThread */);
+    }
 
     const auto collDesc = [&] {
         AutoGetCollection autoColl(opCtx, nss, MODE_IS);
-        return CollectionShardingState::get(opCtx, nss)->getCollectionDescription();
+        auto css = CollectionShardingState::get(opCtx, nss);
+        // If there is a version attached to the OperationContext, validate it
+        if (isVersioned) {
+            css->checkShardVersionOrThrow(opCtx);
+        }
+        return css->getCollectionDescription();
     }();
 
     uassert(ErrorCodes::StaleEpoch,
diff --git a/src/mongo/s/catalog_cache.cpp b/src/mongo/s/catalog_cache.cpp
index 74d481b7b8b..e8ce4063e80 100644
--- a/src/mongo/s/catalog_cache.cpp
+++ b/src/mongo/s/catalog_cache.cpp
@@ -339,6 +339,17 @@ StatusWith<CachedCollectionRoutingInfo> CatalogCache::getShardedCollectionRoutin
     return routingInfoStatus;
 }
 
+StatusWith<CachedCollectionRoutingInfo> CatalogCache::getShardedCollectionRoutingInfo(
+    OperationContext* opCtx, const NamespaceString& nss) {
+    auto routingInfoStatus = _getCollectionRoutingInfoAt(opCtx, nss, boost::none).statusWithInfo;
+    if (routingInfoStatus.isOK() && !routingInfoStatus.getValue().cm()) {
+        return {ErrorCodes::NamespaceNotSharded,
+                str::stream() << "Collection " << nss.ns() << " is not sharded."};
+    }
+
+    return routingInfoStatus;
+}
+
 void CatalogCache::onStaleDatabaseVersion(const StringData dbName,
                                           const DatabaseVersion& databaseVersion) {
     stdx::lock_guard<Latch> lg(_mutex);
diff --git a/src/mongo/s/catalog_cache.h b/src/mongo/s/catalog_cache.h
index 616fb8312be..78ded1c4016 100644
--- a/src/mongo/s/catalog_cache.h
+++ b/src/mongo/s/catalog_cache.h
@@ -196,6 +196,13 @@ public:
         OperationContext* opCtx, const NamespaceString& nss);
 
     /**
+     * Same as getCollectionRoutingInfoWithRefresh above, but in addition returns a
+     * NamespaceNotSharded error if the collection is not sharded.
+     */
+    StatusWith<CachedCollectionRoutingInfo> getShardedCollectionRoutingInfo(
+        OperationContext* opCtx, const NamespaceString& nss);
+
+    /**
      * Non-blocking method that marks the current cached database entry as needing refresh if the
      * entry's databaseVersion matches 'databaseVersion'.
      *
diff --git a/src/mongo/s/commands/cluster_merge_chunks_cmd.cpp b/src/mongo/s/commands/cluster_merge_chunks_cmd.cpp
index 26b9435f91a..a9deb4c4a9d 100644
--- a/src/mongo/s/commands/cluster_merge_chunks_cmd.cpp
+++ b/src/mongo/s/commands/cluster_merge_chunks_cmd.cpp
@@ -103,11 +103,6 @@ public:
                    BSONObjBuilder& result) override {
         const NamespaceString nss(parseNs(dbname, cmdObj));
 
-        auto routingInfo = uassertStatusOK(
-            Grid::get(opCtx)->catalogCache()->getShardedCollectionRoutingInfoWithRefresh(opCtx,
-                                                                                         nss));
-        const auto cm = routingInfo.cm();
-
         vector<BSONObj> bounds;
         if (!FieldParser::extract(cmdObj, boundsField, &bounds, &errmsg)) {
             return false;
@@ -136,6 +131,10 @@ public:
             return false;
         }
 
+        auto routingInfo = uassertStatusOK(
+            Grid::get(opCtx)->catalogCache()->getShardedCollectionRoutingInfo(opCtx, nss));
+        const auto cm = routingInfo.cm();
+
         if (!cm->getShardKeyPattern().isShardKey(minKey) ||
             !cm->getShardKeyPattern().isShardKey(maxKey)) {
             errmsg = str::stream()
@@ -149,6 +148,7 @@ public:
         maxKey = cm->getShardKeyPattern().normalizeShardKey(maxKey);
 
         const auto firstChunk = cm->findIntersectingChunkWithSimpleCollation(minKey);
+        ChunkVersion shardVersion = cm->getVersion(firstChunk.getShardId());
 
         BSONObjBuilder remoteCmdObjB;
         remoteCmdObjB.append(cmdObj[ClusterMergeChunksCommand::nsField()]);
@@ -158,7 +158,8 @@ public:
             Grid::get(opCtx)->shardRegistry()->getConfigServerConnectionString().toString());
         remoteCmdObjB.append(ClusterMergeChunksCommand::shardNameField(),
                              firstChunk.getShardId().toString());
-        remoteCmdObjB.append("epoch", cm->getVersion().epoch());
+        remoteCmdObjB.append("epoch", shardVersion.epoch());
+        shardVersion.appendToCommand(&remoteCmdObjB);
 
         BSONObj remoteResult;