Better

dbms/src/Common/ErrorCodes.cpp

@@ -483,6 +483,7 @@ namespace ErrorCodes
     extern const int INVALID_GRANT = 509;
     extern const int CACHE_DICTIONARY_UPDATE_FAIL = 510;
     extern const int CANNOT_ASSIGN_ALTER = 512;
+    extern const int CONCURRENT_ALTER_IS_PROCESSING = 513;
 
     extern const int KEEPER_EXCEPTION = 999;
     extern const int POCO_EXCEPTION = 1000;

dbms/src/Storages/MergeTree/ReplicatedMergeTreeBlockOutputStream.cpp

@@ -29,6 +29,7 @@ namespace ErrorCodes
     extern const int KEEPER_EXCEPTION;
     extern const int TIMEOUT_EXCEEDED;
     extern const int NO_ACTIVE_REPLICAS;
+    extern const int CONCURRENT_ALTER_IS_PROCESSING;
 }
 
 
@@ -255,7 +256,14 @@ void ReplicatedMergeTreeBlockOutputStream::commitPart(zkutil::ZooKeeperPtr & zoo
         log_entry.toString(),
         zkutil::CreateMode::PersistentSequential));
 
+    /// We check metadata_version has the same version as shared node.
+    /// In other case we may have parts, which nobody will alter.
+    ///
     ops.emplace_back(zkutil::makeCheckRequest(storage.zookeeper_path + "/metadata", storage.getMetadataVersion()));
+
+    /// We update version of block_number/partition node to register fact of new insert.
+    /// If we want to be sure, that no inserts happend in some period of time, than we can receive
+    /// version of all partition nodes inside block numbers and then make check requirests in zookeeper transaction.
     ops.emplace_back(zkutil::makeSetRequest(storage.zookeeper_path + "/block_numbers/" + part->info.partition_id, "", -1));
 
     /// Deletes the information that the block number is used for writing.
@@ -347,6 +355,11 @@ void ReplicatedMergeTreeBlockOutputStream::commitPart(zkutil::ZooKeeperPtr & zoo
 
             throw Exception("Another quorum insert has been already started", ErrorCodes::UNSATISFIED_QUORUM_FOR_PREVIOUS_WRITE);
         }
+        else if (multi_code == Coordination::ZBADVERSION)
+        {
+            transaction.rollback();
+            throw Exception("Current metadata version is not consistent with version in zookeeper. Concurrent alter of metadata is processing now, client must retry", ErrorCodes::CONCURRENT_ALTER_IS_PROCESSING);
+        }
         else
         {
             /// NOTE: We could be here if the node with the quorum existed, but was quickly removed.

dbms/src/Storages/MergeTree/ReplicatedMergeTreeLogEntry.h

@@ -107,12 +107,18 @@ struct ReplicatedMergeTreeLogEntryData
 
     std::shared_ptr<ReplaceRangeEntry> replace_range_entry;
 
-    //TODO(alesap)
-    int alter_version;
-    bool have_mutation;
+    /// ALTER METADATA and MUTATE PART command
 
-    String columns_str;
-    String metadata_str;
+    /// Version of metadata which will be set after this alter
+    /// Also present in MUTATE_PART command, to track mutations
+    /// required for complete alter execution.
+    int alter_version; /// May be equal to -1, if it's normal mutation, not metadata update.
+
+    /// only ALTER METADATA command
+    bool have_mutation; /// If this alter requires additional mutation step, for data update
+
+    String columns_str; /// New columns data corresponding to alter_version
+    String metadata_str; /// New metadata corresponding to alter_version
 
     /// Returns a set of parts that will appear after executing the entry + parts to block
     /// selection of merges. These parts are added to queue.virtual_parts.

dbms/src/Storages/MergeTree/ReplicatedMergeTreeMutationEntry.h

@@ -13,6 +13,11 @@ namespace DB
 class ReadBuffer;
 class WriteBuffer;
 
+/// Mutation entry in /mutations path in zookeeper. This record contains information about blocks
+/// in patitions. We will mutatate all parts with left number less than this numbers.
+///
+/// These entries processed separately from main replication /log, and produce other entries
+/// -- MUTATE_PART.
 struct ReplicatedMergeTreeMutationEntry
 {
     void writeText(WriteBuffer & out) const;
@@ -21,14 +26,24 @@ struct ReplicatedMergeTreeMutationEntry
     String toString() const;
     static ReplicatedMergeTreeMutationEntry parse(const String & str, String znode_name);
 
+    /// Name of znode (mutation-xxxxxxx)
     String znode_name;
 
+    /// Create time of znode
     time_t create_time = 0;
+
+    /// Replica which initiated mutation
     String source_replica;
 
+    /// Accuired numbers of blocks
+    /// partition_id -> block_number
     std::map<String, Int64> block_numbers;
+
+    /// Mutation commands which will give to MUTATE_PART entries
     MutationCommands commands;
 
+    /// Version of metadata. Not equal to -1 only if this mutation
+    /// was created by ALTER MODIFY/DROP queries.
     int alter_version = -1;
 };
 

dbms/src/Storages/MergeTree/ReplicatedMergeTreeQueue.cpp

@@ -150,7 +150,7 @@ void ReplicatedMergeTreeQueue::insertUnlocked(
         }
     }
     if (entry->type == LogEntry::ALTER_METADATA)
-        alter_sequence.addMetadataAlter(entry->alter_version, state_lock);
+        alter_chain.addMetadataAlter(entry->alter_version, state_lock);
 }
 
 
@@ -226,7 +226,7 @@ void ReplicatedMergeTreeQueue::updateStateOnQueueEntryRemoval(
         }
 
         if (entry->type == LogEntry::ALTER_METADATA)
-            alter_sequence.finishMetadataAlter(entry->alter_version, entry->have_mutation, state_lock);
+            alter_chain.finishMetadataAlter(entry->alter_version, entry->have_mutation, state_lock);
     }
     else
     {
@@ -696,7 +696,7 @@ void ReplicatedMergeTreeQueue::updateMutations(zkutil::ZooKeeperPtr zookeeper, C
                     some_mutations_are_probably_done = true;
 
                 if (entry->alter_version != -1)
-                    alter_sequence.addMutationForAlter(entry->alter_version, state_lock);
+                    alter_chain.addMutationForAlter(entry->alter_version, state_lock);
             }
         }
 
@@ -1043,10 +1043,10 @@ bool ReplicatedMergeTreeQueue::shouldExecuteLogEntry(
 
     if (entry.type == LogEntry::ALTER_METADATA)
     {
-        if (!alter_sequence.canExecuteMetaAlter(entry.alter_version, state_lock))
+        if (!alter_chain.canExecuteMetaAlter(entry.alter_version, state_lock))
         {
-            int head_alter = alter_sequence.getHeadAlterVersion(state_lock);
-            out_postpone_reason = "Cannot execute alter data with version: " + std::to_string(entry.alter_version)
+            int head_alter = alter_chain.getHeadAlterVersion(state_lock);
+            out_postpone_reason = "Cannot execute alter metadata with version: " + std::to_string(entry.alter_version)
                 + " because another alter " + std::to_string(head_alter)
                 + " must be executed before";
             return false;
@@ -1055,9 +1055,9 @@ bool ReplicatedMergeTreeQueue::shouldExecuteLogEntry(
 
     if (entry.type == LogEntry::MUTATE_PART && entry.alter_version != -1)
     {
-        if (!alter_sequence.canExecuteDataAlter(entry.alter_version, state_lock))
+        if (!alter_chain.canExecuteDataAlter(entry.alter_version, state_lock))
         {
-            int head_alter = alter_sequence.getHeadAlterVersion(state_lock);
+            int head_alter = alter_chain.getHeadAlterVersion(state_lock);
             if (head_alter == entry.alter_version)
                 out_postpone_reason = "Cannot execute alter data with version: "
                     + std::to_string(entry.alter_version) + " because metadata still not altered";
@@ -1352,7 +1352,7 @@ bool ReplicatedMergeTreeQueue::tryFinalizeMutations(zkutil::ZooKeeperPtr zookeep
                     LOG_INFO(log, "Seems like we jumped over mutation " << znode << " when downloaded part with bigger mutation number."
                         << " It's OK, tasks for rest parts will be skipped, but probably a lot of mutations were executed concurrently on different replicas.");
                     mutation.parts_to_do.clear();
-                    alter_sequence.finishDataAlter(mutation.entry->alter_version, lock);
+                    alter_chain.finishDataAlter(mutation.entry->alter_version, lock);
                 }
             }
             else if (mutation.parts_to_do.size() == 0)
@@ -1393,7 +1393,7 @@ bool ReplicatedMergeTreeQueue::tryFinalizeMutations(zkutil::ZooKeeperPtr zookeep
                 if (entry->alter_version != -1)
                 {
                     LOG_TRACE(log, "Finishing data alter with version " << entry->alter_version << " for entry " << entry->znode_name);
-                    alter_sequence.finishDataAlter(entry->alter_version, lock);
+                    alter_chain.finishDataAlter(entry->alter_version, lock);
                 }
             }
         }

dbms/src/Storages/MergeTree/ReplicatedMergeTreeQueue.h

@@ -9,7 +9,7 @@
 #include <Storages/MergeTree/MergeTreeData.h>
 #include <Storages/MergeTree/MergeTreeMutationStatus.h>
 #include <Storages/MergeTree/ReplicatedMergeTreeQuorumAddedParts.h>
-#include <Storages/MergeTree/ReplicatedQueueAlterState.h>
+#include <Storages/MergeTree/ReplicatedQueueAlterChain.h>
 
 #include <Common/ZooKeeper/ZooKeeper.h>
 #include <Core/BackgroundSchedulePool.h>
@@ -132,7 +132,7 @@ private:
     /// Provides only one simultaneous call to pullLogsToQueue.
     std::mutex pull_logs_to_queue_mutex;
 
-    AlterSequence alter_sequence;
+    ReplicatedQueueAlterChain alter_chain;
 
     /// List of subscribers
     /// A subscriber callback is called when an entry queue is deleted

dbms/src/Storages/MergeTree/ReplicatedQueueAlterChain.h

@@ -14,7 +14,7 @@ namespace ErrorCodes
     extern const int LOGICAL_ERROR;
 }
 
-class AlterSequence
+class ReplicatedQueueAlterChain
 {
 private:
     struct AlterState

dbms/src/Storages/StorageReplicatedMergeTree.cpp

@@ -3261,7 +3261,6 @@ void StorageReplicatedMergeTree::alter(
 {
     assertNotReadonly();
 
-    auto maybe_mutation_commands = params.getMutationCommands(getInMemoryMetadata());
     auto table_id = getStorageID();
 
     if (params.isSettingsAlter())
@@ -3286,78 +3285,86 @@ void StorageReplicatedMergeTree::alter(
 
     auto zookeeper = getZooKeeper();
 
-    ReplicatedMergeTreeLogEntryData entry;
-
+    std::optional<ReplicatedMergeTreeLogEntryData> alter_entry;
     std::optional<String> mutation_znode;
+
     while (true) {
 
+        /// Clear nodes from previous iteration
+        alter_entry.emplace();
+        mutation_znode.emplace();
+
         /// We can safely read structure, because we guarded with alter_intention_lock
         if (is_readonly)
             throw Exception("Can't ALTER readonly table", ErrorCodes::TABLE_IS_READ_ONLY);
 
 
-        StorageInMemoryMetadata metadata = getInMemoryMetadata();
-        params.apply(metadata);
+        StorageInMemoryMetadata current_metadata = getInMemoryMetadata();
 
+        StorageInMemoryMetadata future_metadata = current_metadata;
+        params.apply(future_metadata);
 
+        ReplicatedMergeTreeTableMetadata future_metadata_in_zk(*this);
+        if (ast_to_str(future_metadata.order_by_ast) != ast_to_str(current_metadata.order_by_ast))
+            future_metadata_in_zk.sorting_key = serializeAST(*extractKeyExpressionList(future_metadata.order_by_ast));
 
-        ReplicatedMergeTreeTableMetadata new_metadata(*this);
-        if (ast_to_str(metadata.order_by_ast) != ast_to_str(order_by_ast))
-            new_metadata.sorting_key = serializeAST(*extractKeyExpressionList(metadata.order_by_ast));
+        if (ast_to_str(future_metadata.ttl_for_table_ast) != ast_to_str(current_metadata.ttl_for_table_ast))
+            future_metadata_in_zk.ttl_table = serializeAST(*future_metadata.ttl_for_table_ast);
 
-        if (ast_to_str(metadata.ttl_for_table_ast) != ast_to_str(ttl_table_ast))
-            new_metadata.ttl_table = serializeAST(*metadata.ttl_for_table_ast);
+        String new_indices_str = future_metadata.indices.toString();
+        if (new_indices_str != current_metadata.indices.toString())
+            future_metadata_in_zk.skip_indices = new_indices_str;
 
-        String new_indices_str = metadata.indices.toString();
-        if (new_indices_str != getIndices().toString())
-            new_metadata.skip_indices = new_indices_str;
-
-        String new_constraints_str = metadata.constraints.toString();
-        if (new_constraints_str != getConstraints().toString())
-            new_metadata.constraints = new_constraints_str;
+        String new_constraints_str = future_metadata.constraints.toString();
+        if (new_constraints_str != current_metadata.indices.toString())
+            future_metadata_in_zk.constraints = new_constraints_str;
 
         Coordination::Requests ops;
 
-        String new_metadata_str = new_metadata.toString();
+        String new_metadata_str = future_metadata_in_zk.toString();
         ops.emplace_back(zkutil::makeSetRequest(zookeeper_path + "/metadata", new_metadata_str, metadata_version));
 
-        String new_columns_str = metadata.columns.toString();
+        String new_columns_str = future_metadata.columns.toString();
         ops.emplace_back(zkutil::makeSetRequest(zookeeper_path + "/columns", new_columns_str, -1));
 
 
+        if (ast_to_str(current_metadata.settings_ast) != ast_to_str(future_metadata.settings_ast))
         {
             lockStructureExclusively(table_lock_holder, query_context.getCurrentQueryId());
-            auto old_metadata = getInMemoryMetadata();
-            old_metadata.settings_ast = metadata.settings_ast;
-            changeSettings(metadata.settings_ast, table_lock_holder);
-            global_context.getDatabase(table_id.database_name)->alterTable(query_context, table_id.table_name, old_metadata);
+            /// Just change settings
+            current_metadata.settings_ast = future_metadata.settings_ast;
+            changeSettings(current_metadata.settings_ast, table_lock_holder);
+            global_context.getDatabase(table_id.database_name)->alterTable(query_context, table_id.table_name, current_metadata);
         }
 
-        entry.type = LogEntry::ALTER_METADATA;
-        entry.source_replica = replica_name;
-        entry.metadata_str = new_metadata_str;
-        entry.columns_str = new_columns_str;
-        entry.alter_version = metadata_version + 1;
+        /// We can be sure, that in case of successfull commit in zookeeper our
+        /// version will increments by 1. Because we update with version check.
+        int new_metadata_version = metadata_version + 1;
 
-        entry.create_time = time(nullptr);
-        if (!maybe_mutation_commands.empty())
-            entry.have_mutation = true;
-        else
-            entry.have_mutation = false;
+        alter_entry->type = LogEntry::ALTER_METADATA;
+        alter_entry->source_replica = replica_name;
+        alter_entry->metadata_str = new_metadata_str;
+        alter_entry->columns_str = new_columns_str;
+        alter_entry->alter_version = new_metadata_version;
+        alter_entry->create_time = time(nullptr);
 
-        ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/log/log-", entry.toString(), zkutil::CreateMode::PersistentSequential));
 
+        auto maybe_mutation_commands = params.getMutationCommands(current_metadata);
+        alter_entry->have_mutation = !maybe_mutation_commands.empty();
+
+        ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/log/log-", alter_entry->toString(), zkutil::CreateMode::PersistentSequential));
 
         std::optional<EphemeralLocksInAllPartitions> lock_holder;
-        size_t partitions_count = 0;
-        if (!maybe_mutation_commands.empty())
+
+        /// No we will prepare mutations record
+        if (alter_entry->have_mutation)
         {
             String mutations_path = zookeeper_path + "/mutations";
 
             ReplicatedMergeTreeMutationEntry mutation_entry;
             mutation_entry.source_replica = replica_name;
             mutation_entry.commands = maybe_mutation_commands;
-            mutation_entry.alter_version = metadata_version + 1;
+            mutation_entry.alter_version = new_metadata_version;
             Coordination::Stat mutations_stat;
             zookeeper->get(mutations_path, &mutations_stat);
 
@@ -3382,7 +3389,6 @@ void StorageReplicatedMergeTree::alter(
             {
                 mutation_entry.block_numbers[lock.partition_id] = lock.number;
                 ops.emplace_back(zkutil::makeCheckRequest(zookeeper_path + "/block_numbers/" + lock.partition_id, partition_versions[lock.partition_id]));
-                partitions_count++;
             }
 
             mutation_entry.create_time = time(nullptr);
@@ -3390,7 +3396,6 @@ void StorageReplicatedMergeTree::alter(
             ops.emplace_back(zkutil::makeSetRequest(mutations_path, String(), mutations_stat.version));
             ops.emplace_back(
                 zkutil::makeCreateRequest(mutations_path + "/", mutation_entry.toString(), zkutil::CreateMode::PersistentSequential));
-
         }
 
         Coordination::Responses results;
@@ -3399,11 +3404,11 @@ void StorageReplicatedMergeTree::alter(
         if (rc == Coordination::ZOK)
         {
             queue.pullLogsToQueue(zookeeper);
-            if (entry.have_mutation)
+            if (alter_entry->have_mutation)
             {
                 /// Record in replication /log
                 String alter_path = dynamic_cast<const Coordination::CreateResponse &>(*results[2]).path_created;
-                entry.znode_name = alter_path.substr(alter_path.find_last_of('/') + 1);
+                alter_entry->znode_name = alter_path.substr(alter_path.find_last_of('/') + 1);
 
                 /// Record in /mutations
                 String mutation_path = dynamic_cast<const Coordination::CreateResponse &>(*results.back()).path_created;
@@ -3413,7 +3418,7 @@ void StorageReplicatedMergeTree::alter(
             {
                 /// Record in replication /log
                 String alter_path = dynamic_cast<const Coordination::CreateResponse &>(*results.back()).path_created;
-                entry.znode_name = alter_path.substr(alter_path.find_last_of('/') + 1);
+                alter_entry->znode_name = alter_path.substr(alter_path.find_last_of('/') + 1);
             }
             break;
         }
@@ -3437,9 +3442,9 @@ void StorageReplicatedMergeTree::alter(
 
     std::vector<String> unwaited;
     if (query_context.getSettingsRef().replication_alter_partitions_sync == 2)
-        unwaited = waitForAllReplicasToProcessLogEntry(entry, false);
+        unwaited = waitForAllReplicasToProcessLogEntry(*alter_entry, false);
     else if (query_context.getSettingsRef().replication_alter_partitions_sync == 1)
-        waitForReplicaToProcessLogEntry(replica_name, entry);
+        waitForReplicaToProcessLogEntry(replica_name, *alter_entry);
 
     if (!unwaited.empty())
         throw Exception("Some replicas doesn't finish metadata alter", ErrorCodes::UNFINISHED);
@@ -4534,111 +4539,6 @@ void StorageReplicatedMergeTree::waitMutation(const String & znode_name, size_t
     }
 }
 
-
-ReplicatedMergeTreeMutationEntry StorageReplicatedMergeTree::prepareMutationEntry(
-    zkutil::ZooKeeperPtr zookeeper, const MutationCommands & commands, Coordination::Requests & requests, int alter_version) const
-{
-    String mutations_path = zookeeper_path + "/mutations";
-
-    ReplicatedMergeTreeMutationEntry entry;
-    entry.source_replica = replica_name;
-    entry.commands = commands;
-    entry.alter_version = alter_version;
-    Coordination::Stat mutations_stat;
-    zookeeper->get(mutations_path, &mutations_stat);
-
-    EphemeralLocksInAllPartitions block_number_locks(zookeeper_path + "/block_numbers", "block-", zookeeper_path + "/temp", *zookeeper);
-
-    for (const auto & lock : block_number_locks.getLocks())
-        entry.block_numbers[lock.partition_id] = lock.number;
-
-    entry.create_time = time(nullptr);
-
-    requests.emplace_back(zkutil::makeSetRequest(mutations_path, String(), mutations_stat.version));
-    requests.emplace_back(zkutil::makeCreateRequest(mutations_path + "/", entry.toString(), zkutil::CreateMode::PersistentSequential));
-
-    return entry;
-}
-
-void StorageReplicatedMergeTree::mutateImpl(
-    zkutil::ZooKeeperPtr zookeeper,
-    const Coordination::Requests & requests,
-    ReplicatedMergeTreeMutationEntry & entry)
-{
-    /// Overview of the mutation algorithm.
-    ///
-    /// When the client executes a mutation, this method is called. It acquires block numbers in all
-    /// partitions, saves them in the mutation entry and writes the mutation entry to a new ZK node in
-    /// the /mutations folder. This block numbers are needed to determine which parts should be mutated and
-    /// which shouldn't (parts inserted after the mutation will have the block number higher than the
-    /// block number acquired by the mutation in that partition and so will not be mutatied).
-    /// This block number is called "mutation version" in that partition.
-    ///
-    /// Mutation versions are acquired atomically in all partitions, so the case when an insert in some
-    /// partition has the block number higher than the mutation version but the following insert into another
-    /// partition acquires the block number lower than the mutation version in that partition is impossible.
-    /// Another important invariant: mutation entries appear in /mutations in the order of their mutation
-    /// versions (in any partition). This means that mutations form a sequence and we can execute them in
-    /// the order of their mutation versions and not worry that some mutation with the smaller version
-    /// will suddenly appear.
-    ///
-    /// During mutations individual parts are immutable - when we want to change the contents of a part
-    /// we prepare the new part and add it to MergeTreeData (the original part gets replaced). The fact that
-    /// we have mutated the part is recorded in the part->info.mutation field of MergeTreePartInfo.
-    /// The relation with the original part is preserved because the new part covers the same block range
-    /// as the original one.
-    ///
-    /// We then can for each part determine its "mutation version": the version of the last mutation in
-    /// the mutation sequence that we regard as already applied to that part. All mutations with the greater
-    /// version number will still need to be applied to that part.
-    ///
-    /// Execution of mutations is done asynchronously. All replicas watch the /mutations directory and
-    /// load new mutation entries as they appear (see mutationsUpdatingTask()). Next we need to determine
-    /// how to mutate individual parts consistently with part merges. This is done by the leader replica
-    /// (see mergeSelectingTask() and class ReplicatedMergeTreeMergePredicate for details). Important
-    /// invariants here are that a) all source parts for a single merge must have the same mutation version
-    /// and b) any part can be mutated only once or merged only once (e.g. once we have decided to mutate
-    /// a part then we need to execute that mutation and can assign merges only to the new part and not to the
-    /// original part). Multiple consecutive mutations can be executed at once (without writing the
-    /// intermediate result to a part).
-    ///
-    /// Leader replica records its decisions to the replication log (/log directory in ZK) in the form of
-    /// MUTATE_PART entries and all replicas then execute them in the background pool
-    /// (see tryExecutePartMutation() function). When a replica encounters a MUTATE_PART command, it is
-    /// guaranteed that the corresponding mutation entry is already loaded (when we pull entries from
-    /// replication log into the replica queue, we also load mutation entries). Note that just as with merges
-    /// the replica can decide not to do the mutation locally and fetch the mutated part from another replica
-    /// instead.
-    ///
-    /// Mutations of individual parts are in fact pretty similar to merges, e.g. their assignment and execution
-    /// is governed by the same storage_settings. TODO: support a single "merge-mutation" operation when the data
-    /// read from the the source parts is first mutated on the fly to some uniform mutation version and then
-    /// merged to a resulting part.
-    ///
-    /// After all needed parts are mutated (i.e. all active parts have the mutation version greater than
-    /// the version of this mutation), the mutation is considered done and can be deleted.
-
-
-    Coordination::Responses responses;
-    int32_t rc = zookeeper->tryMulti(requests, responses);
-
-    if (rc == Coordination::ZOK)
-    {
-        const String & path_created =
-            dynamic_cast<const Coordination::CreateResponse *>(responses[1].get())->path_created;
-        entry.znode_name = path_created.substr(path_created.find_last_of('/') + 1);
-        LOG_TRACE(log, "Created mutation with ID " << entry.znode_name);
-    }
-    else if (rc == Coordination::ZBADVERSION)
-        /// This error mean, that parallel mutation is created in mutations queue (/mutations) right now.
-        /// (NOTE: concurrent mutations execution is OK, but here we have case with concurrent mutation intention from client)
-        /// We can retry this error by ourself, but mutations is not designed for highly concurrent execution.
-        /// So, if client sure that he do what he want, than he should retry.
-        throw Coordination::Exception("Parallel mutation is creating right now. Client should retry.", rc);
-    else
-        throw Coordination::Exception("Unable to create a mutation znode", rc);
-}
-
 std::vector<MergeTreeMutationStatus> StorageReplicatedMergeTree::getMutationsStatus() const
 {
     return queue.getMutationsStatus();

dbms/src/Storages/StorageReplicatedMergeTree.h

@@ -109,8 +109,6 @@ public:
     void alterPartition(const ASTPtr & query, const PartitionCommands & commands, const Context & query_context) override;
 
     void mutate(const MutationCommands & commands, const Context & context) override;
-    ReplicatedMergeTreeMutationEntry prepareMutationEntry(zkutil::ZooKeeperPtr zk,  const MutationCommands & commands, Coordination::Requests & requests, int alter_version = -1) const;
-    void mutateImpl(zkutil::ZooKeeperPtr zookeeper, const Coordination::Requests & requests, ReplicatedMergeTreeMutationEntry & entry);
     void waitMutation(const String & znode_name, size_t mutation_sync) const;
     std::vector<MergeTreeMutationStatus> getMutationsStatus() const override;
     CancellationCode killMutation(const String & mutation_id) override;