SERVER-56515 Make mergeChunks consider the 'incrementChunkMajorVersionOnChunkSplits' parameter

2 files changed, 41 insertions, 11 deletions

diff --git a/jstests/sharding/major_version_check.js b/jstests/sharding/major_version_check.js
index 2ae32fe6cae..0626074abe2 100644
--- a/jstests/sharding/major_version_check.js
+++ b/jstests/sharding/major_version_check.js
@@ -4,8 +4,7 @@
 (function() {
     'use strict';
 
-    // Test with default value of incrementChunkMajorVersionOnChunkSplits, which is
-    // false.
+    // Test with default value of incrementChunkMajorVersionOnChunkSplits, which is false.
     (() => {
         var st = new ShardingTest({shards: 1, mongos: 2});
 
@@ -39,7 +38,6 @@
         staleMongos.getCollection(coll + "").findOne();
 
         printjson(staleMongos.getDB("admin").runCommand({getShardVersion: coll + ""}));
-
         assert.eq(Timestamp(1, 0),
                   staleMongos.getDB("admin").runCommand({getShardVersion: coll + ""}).version);
 
@@ -48,10 +46,14 @@
         staleMongos.getCollection(coll + "").findOne();
 
         printjson(staleMongos.getDB("admin").runCommand({getShardVersion: coll + ""}));
-
         assert.eq(Timestamp(1, 0),
                   staleMongos.getDB("admin").runCommand({getShardVersion: coll + ""}).version);
 
+        // Merge the just-split chunks and ensure the major version didn't go up
+        assert.commandWorked(
+            admin.runCommand({mergeChunks: coll + "", bounds: [{_id: MinKey}, {_id: MaxKey}]}));
+        assert.eq(Timestamp(1, 3), admin.runCommand({getShardVersion: coll + ""}).version);
+
         st.stop();
     })();
 
@@ -123,6 +125,11 @@
         assert.eq(Timestamp(2, 2),
                   staleMongos.getDB("admin").runCommand({getShardVersion: coll + ""}).version);
 
+        // Merge the just-split chunks and ensure the major version went up
+        assert.commandWorked(
+            admin.runCommand({mergeChunks: coll + "", bounds: [{_id: MinKey}, {_id: MaxKey}]}));
+        assert.eq(Timestamp(3, 0), admin.runCommand({getShardVersion: coll + ""}).version);
+
         st.stop();
     })();
 })();
diff --git a/src/mongo/db/s/config/sharding_catalog_manager_chunk_operations.cpp b/src/mongo/db/s/config/sharding_catalog_manager_chunk_operations.cpp
index 033a96c6a25..453ae919b72 100644
--- a/src/mongo/db/s/config/sharding_catalog_manager_chunk_operations.cpp
+++ b/src/mongo/db/s/config/sharding_catalog_manager_chunk_operations.cpp
@@ -370,13 +370,12 @@ Status ShardingCatalogManager::commitChunkSplit(OperationContext* opCtx,
     std::vector<ChunkType> newChunks;
 
     ChunkVersion currentMaxVersion = collVersion;
-    // Increment the major version only if the shard that owns the chunk being split has version ==
-    // collection version. See SERVER-41480 for details.
+    // Increment the major version only if the shard that owns the chunk being split has
+    // shardVersion == collection version. See SERVER-41480 for details.
     if (incrementChunkMajorVersionOnChunkSplits.load() && shardVersion == collVersion) {
         currentMaxVersion.incMajor();
     }
 
-
     auto startKey = range.getMin();
     auto newChunkBounds(splitPoints);
     newChunkBounds.push_back(range.getMax());
@@ -583,8 +582,7 @@ Status ShardingCatalogManager::commitChunkMerge(OperationContext* opCtx,
             1));                             // Limit 1.
 
     if (!swCollVersion.isOK()) {
-        return swCollVersion.getStatus().withContext(str::stream()
-                                                     << "mergeChunk cannot merge chunks.");
+        return swCollVersion.getStatus().withContext("mergeChunk cannot merge chunks.");
     }
 
     auto collVersion = swCollVersion.getValue();
@@ -596,6 +594,25 @@ Status ShardingCatalogManager::commitChunkMerge(OperationContext* opCtx,
                 "that the collection was dropped and re-created."};
     }
 
+    // Get the shard version (max chunk version) for the shard requesting the merge.
+    auto swShardVersion = getMaxChunkVersionFromQueryResponse(
+        nss,
+        Grid::get(opCtx)->shardRegistry()->getConfigShard()->exhaustiveFindOnConfig(
+            opCtx,
+            ReadPreferenceSetting{ReadPreference::PrimaryOnly},
+            repl::ReadConcernLevel::kLocalReadConcern,
+            ChunkType::ConfigNS,
+            BSON("ns" << nss.ns() << "shard"
+                      << shardName),         // Query all chunks for this namespace and shard.
+            BSON(ChunkType::lastmod << -1),  // Sort by version.
+            1));                             // Limit 1.
+
+    if (!swShardVersion.isOK()) {
+        return swShardVersion.getStatus().withContext("mergeChunk cannot merge chunks.");
+    }
+
+    auto shardVersion = swShardVersion.getValue();
+
     // Build chunks to be merged
     std::vector<ChunkType> chunksToMerge;
 
@@ -636,7 +653,13 @@ Status ShardingCatalogManager::commitChunkMerge(OperationContext* opCtx,
     }
 
     ChunkVersion mergeVersion = collVersion;
-    mergeVersion.incMinor();
+    // Increment the major version only if the shard that owns the chunks being merged has
+    // shardVersion == collection version. See SERVER-41480 for details.
+    if (incrementChunkMajorVersionOnChunkSplits.load() && shardVersion == collVersion) {
+        mergeVersion.incMajor();
+    } else {
+        mergeVersion.incMinor();
+    }
 
     auto updates = buildMergeChunksTransactionUpdates(chunksToMerge, mergeVersion, validAfter);
     auto preCond = buildMergeChunksTransactionPrecond(chunksToMerge, collVersion);
@@ -668,7 +691,7 @@ Status ShardingCatalogManager::commitChunkMerge(OperationContext* opCtx,
     Grid::get(opCtx)
         ->catalogClient()
         ->logChange(opCtx, "merge", nss.ns(), logDetail.obj(), WriteConcernOptions())
-        .transitional_ignore();
+        .ignore();
 
     return applyOpsStatus;
 }