SERVER-45368 Allow collection/index creation inside txns for sharding

This patch ensures unprepared transactions in a sharded cluster can
create new collections and indexes.

7 files changed, 13 insertions, 18 deletions

diff --git a/buildscripts/resmokeconfig/suites/sharded_causally_consistent_jscore_txns_passthrough.yml b/buildscripts/resmokeconfig/suites/sharded_causally_consistent_jscore_txns_passthrough.yml
index c883203614a..4ed9f139ae1 100644
--- a/buildscripts/resmokeconfig/suites/sharded_causally_consistent_jscore_txns_passthrough.yml
+++ b/buildscripts/resmokeconfig/suites/sharded_causally_consistent_jscore_txns_passthrough.yml
@@ -30,12 +30,6 @@ selector:
   # attached to statements in a transaction beyond the first one.
   - jstests/core/txns/non_transactional_operations_on_session_with_transaction.js
 
-  # TODO(SERVER-45368) re-enable once collection creation is permitted in cross-shard transactions.
-  - jstests/core/txns/create_collection.js
-  - jstests/core/txns/create_collection_parallel.js
-  - jstests/core/txns/create_indexes.js
-  - jstests/core/txns/create_indexes_parallel.js
-
   exclude_with_any_tags:
   - assumes_against_mongod_not_mongos
   - does_not_support_causal_consistency
diff --git a/buildscripts/resmokeconfig/suites/sharded_collections_causally_consistent_jscore_txns_passthrough.yml b/buildscripts/resmokeconfig/suites/sharded_collections_causally_consistent_jscore_txns_passthrough.yml
index 9debf1e661b..7c899f771ec 100644
--- a/buildscripts/resmokeconfig/suites/sharded_collections_causally_consistent_jscore_txns_passthrough.yml
+++ b/buildscripts/resmokeconfig/suites/sharded_collections_causally_consistent_jscore_txns_passthrough.yml
@@ -29,7 +29,9 @@ selector:
   # attached to statements in a transaction beyond the first one.
   - jstests/core/txns/non_transactional_operations_on_session_with_transaction.js
 
-  # TODO(SERVER-45368) re-enable once collection creation is permitted in cross-shard transactions.
+  # These workloads explicitly create collections inside multi-document transactions. These are
+  # non-idempotent operations, and the implicit collection sharding logic upon collection access
+  # results in premature collection creation, causing the workloads to fail.
   - jstests/core/txns/create_collection.js
   - jstests/core/txns/create_collection_parallel.js
   - jstests/core/txns/create_indexes.js
diff --git a/buildscripts/resmokeconfig/suites/sharded_jscore_txns.yml b/buildscripts/resmokeconfig/suites/sharded_jscore_txns.yml
index 1b5722b7eba..87ebb6eead4 100644
--- a/buildscripts/resmokeconfig/suites/sharded_jscore_txns.yml
+++ b/buildscripts/resmokeconfig/suites/sharded_jscore_txns.yml
@@ -26,13 +26,6 @@ selector:
   # Uses hangAfterCollectionInserts failpoint not available on mongos.
   - jstests/core/txns/speculative_snapshot_includes_all_writes.js
 
-  # TODO(SERVER-45368) re-enable once collection creation is permitted in cross-shard transactions.
-  - jstests/core/txns/create_collection.js
-  - jstests/core/txns/create_collection_parallel.js
-  - jstests/core/txns/create_indexes.js
-  - jstests/core/txns/create_indexes_parallel.js
-
-
   exclude_with_any_tags:
   - assumes_against_mongod_not_mongos
   # Transactions are not allowed to operate on capped collections.
diff --git a/buildscripts/resmokeconfig/suites/sharded_jscore_txns_sharded_collections.yml b/buildscripts/resmokeconfig/suites/sharded_jscore_txns_sharded_collections.yml
index d617ebc9504..f7f026c3be5 100644
--- a/buildscripts/resmokeconfig/suites/sharded_jscore_txns_sharded_collections.yml
+++ b/buildscripts/resmokeconfig/suites/sharded_jscore_txns_sharded_collections.yml
@@ -25,7 +25,9 @@ selector:
   # View tests aren't expected to work when collections are implicitly sharded.
   - jstests/core/txns/view_reads_in_transaction.js
 
-  # TODO(SERVER-45368) re-enable once collection creation is permitted in cross-shard transactions.
+  # These workloads explicitly create collections inside multi-document transactions. These are
+  # non-idempotent operations, and the implicit collection sharding logic upon collection access
+  # results in premature collection creation, causing the workloads to fail.
   - jstests/core/txns/create_collection.js
   - jstests/core/txns/create_collection_parallel.js
   - jstests/core/txns/create_indexes.js
diff --git a/jstests/core/txns/create_collection.js b/jstests/core/txns/create_collection.js
index ad1b7f14bc1..90ee9305c5e 100644
--- a/jstests/core/txns/create_collection.js
+++ b/jstests/core/txns/create_collection.js
@@ -28,6 +28,7 @@ session.commitTransaction();
 assert.eq(sessionColl.find({}).itcount(), 1);
 
 sessionColl.drop({writeConcern: {w: "majority"}});
+
 jsTest.log("Testing multiple createCollections in a transaction");
 session.startTransaction({writeConcern: {w: "majority"}});
 createCollAndCRUDInTxn(sessionDB, collName);
@@ -46,13 +47,13 @@ assert.commandWorked(session.abortTransaction_forTesting());
 
 assert.eq(sessionColl.find({}).itcount(), 0);
 
+jsTest.log("Testing createCollection on an existing collection in a transaction (SHOULD ABORT)");
 assert.commandWorked(sessionDB.runCommand({create: collName, writeConcern: {w: "majority"}}));
-jsTest.log(
-    "Testing createCollection on an existing collection in a transaction that aborts (SHOULD FAIL)");
 session.startTransaction({writeConcern: {w: "majority"}});
 createCollAndCRUDInTxn(sessionDB, secondCollName);
 assert.commandFailedWithCode(sessionDB.runCommand({create: collName}), ErrorCodes.NamespaceExists);
 assert.commandFailedWithCode(session.abortTransaction_forTesting(), ErrorCodes.NoSuchTransaction);
+
 assert.eq(sessionColl.find({}).itcount(), 0);
 assert.eq(secondSessionColl.find({}).itcount(), 0);
 
diff --git a/jstests/core/txns/create_collection_parallel.js b/jstests/core/txns/create_collection_parallel.js
index a3ee0b94087..401606ef253 100644
--- a/jstests/core/txns/create_collection_parallel.js
+++ b/jstests/core/txns/create_collection_parallel.js
@@ -36,6 +36,7 @@ assert.eq(sessionColl.find({}).itcount(), 1);
 
 assert.commandFailedWithCode(secondSessionDB.runCommand({create: collName}),
                              ErrorCodes.NamespaceExists);
+
 assert.commandFailedWithCode(secondSession.abortTransaction_forTesting(),
                              ErrorCodes.NoSuchTransaction);
 
diff --git a/src/mongo/s/commands/cluster_create_cmd.cpp b/src/mongo/s/commands/cluster_create_cmd.cpp
index d869ce626d1..d1a3fc792fc 100644
--- a/src/mongo/s/commands/cluster_create_cmd.cpp
+++ b/src/mongo/s/commands/cluster_create_cmd.cpp
@@ -138,7 +138,9 @@ public:
         uassertStatusOK(response.swResponse);
         const auto createStatus =
             mongo::getStatusFromCommandResult(response.swResponse.getValue().data);
-        if (createStatus == ErrorCodes::NamespaceExists) {
+        if (createStatus == ErrorCodes::NamespaceExists && !opCtx->inMultiDocumentTransaction()) {
+            // NamespaceExists will cause multi-document transactions to implicitly abort, so
+            // mongos should surface this error to the client.
             CollectionOptions options = uassertStatusOK(CollectionOptions::parse(cmdObj));
             checkCollectionOptions(opCtx, nss, options);
         } else {