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ClickHouse/programs/copier/ClusterCopier.cpp

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#include "ClusterCopier.h"
#include "Internals.h"
#include "StatusAccumulator.h"
#include <Common/ZooKeeper/ZooKeeper.h>
#include <Common/ZooKeeper/KeeperException.h>
#include <Common/setThreadName.h>
#include <IO/ConnectionTimeoutsContext.h>
#include <Interpreters/InterpreterInsertQuery.h>
#include <Parsers/ASTFunction.h>
#include <Processors/Transforms/ExpressionTransform.h>
#include <QueryPipeline/QueryPipelineBuilder.h>
#include <QueryPipeline/Chain.h>
#include <Processors/Executors/PullingPipelineExecutor.h>
#include <Processors/Executors/PushingPipelineExecutor.h>
#include <Processors/Sources/RemoteSource.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NOT_IMPLEMENTED;
extern const int LOGICAL_ERROR;
extern const int UNFINISHED;
extern const int BAD_ARGUMENTS;
}
void ClusterCopier::init()
{
auto zookeeper = getContext()->getZooKeeper();
task_description_watch_callback = [this] (const Coordination::WatchResponse & response)
{
if (response.error != Coordination::Error::ZOK)
return;
UInt64 version = ++task_description_version;
LOG_INFO(log, "Task description should be updated, local version {}", version);
};
task_description_path = task_zookeeper_path + "/description";
task_cluster = std::make_unique<TaskCluster>(task_zookeeper_path, working_database_name);
reloadTaskDescription();
task_cluster->loadTasks(*task_cluster_current_config);
getContext()->setClustersConfig(task_cluster_current_config, false, task_cluster->clusters_prefix);
/// Set up shards and their priority
task_cluster->random_engine.seed(task_cluster->random_device());
for (auto & task_table : task_cluster->table_tasks)
{
task_table.cluster_pull = getContext()->getCluster(task_table.cluster_pull_name);
task_table.cluster_push = getContext()->getCluster(task_table.cluster_push_name);
task_table.initShards(task_cluster->random_engine);
}
LOG_INFO(log, "Will process {} table tasks", task_cluster->table_tasks.size());
/// Do not initialize tables, will make deferred initialization in process()
zookeeper->createAncestors(getWorkersPathVersion() + "/");
zookeeper->createAncestors(getWorkersPath() + "/");
/// Init status node
zookeeper->createIfNotExists(task_zookeeper_path + "/status", "{}");
}
template <typename T>
decltype(auto) ClusterCopier::retry(T && func, UInt64 max_tries)
{
std::exception_ptr exception;
if (max_tries == 0)
throw Exception("Cannot perform zero retries", ErrorCodes::LOGICAL_ERROR);
for (UInt64 try_number = 1; try_number <= max_tries; ++try_number)
{
try
{
return func();
}
catch (...)
{
exception = std::current_exception();
if (try_number < max_tries)
{
tryLogCurrentException(log, "Will retry");
std::this_thread::sleep_for(retry_delay_ms);
}
}
}
std::rethrow_exception(exception);
}
void ClusterCopier::discoverShardPartitions(const ConnectionTimeouts & timeouts, const TaskShardPtr & task_shard)
{
TaskTable & task_table = task_shard->task_table;
LOG_INFO(log, "Discover partitions of shard {}", task_shard->getDescription());
auto get_partitions = [&] () { return getShardPartitions(timeouts, *task_shard); };
auto existing_partitions_names = retry(get_partitions, 60);
Strings filtered_partitions_names;
Strings missing_partitions;
/// Check that user specified correct partition names
auto check_partition_format = [] (const DataTypePtr & type, const String & partition_text_quoted)
{
MutableColumnPtr column_dummy = type->createColumn();
ReadBufferFromString rb(partition_text_quoted);
try
{
type->getDefaultSerialization()->deserializeTextQuoted(*column_dummy, rb, FormatSettings());
}
catch (Exception & e)
{
throw Exception("Partition " + partition_text_quoted + " has incorrect format. " + e.displayText(), ErrorCodes::BAD_ARGUMENTS);
}
};
if (task_table.has_enabled_partitions)
{
/// Process partition in order specified by <enabled_partitions/>
for (const String & partition_name : task_table.enabled_partitions)
{
/// Check that user specified correct partition names
check_partition_format(task_shard->partition_key_column.type, partition_name);
auto it = existing_partitions_names.find(partition_name);
/// Do not process partition if it is not in enabled_partitions list
if (it == existing_partitions_names.end())
{
missing_partitions.emplace_back(partition_name);
continue;
}
filtered_partitions_names.emplace_back(*it);
}
for (const String & partition_name : existing_partitions_names)
{
if (!task_table.enabled_partitions_set.count(partition_name))
{
LOG_INFO(log, "Partition {} will not be processed, since it is not in enabled_partitions of {}", partition_name, task_table.table_id);
}
}
}
else
{
for (const String & partition_name : existing_partitions_names)
filtered_partitions_names.emplace_back(partition_name);
}
for (const String & partition_name : filtered_partitions_names)
{
const size_t number_of_splits = task_table.number_of_splits;
task_shard->partition_tasks.emplace(partition_name, ShardPartition(*task_shard, partition_name, number_of_splits));
task_shard->checked_partitions.emplace(partition_name, true);
auto shard_partition_it = task_shard->partition_tasks.find(partition_name);
PartitionPieces & shard_partition_pieces = shard_partition_it->second.pieces;
for (size_t piece_number = 0; piece_number < number_of_splits; ++piece_number)
{
bool res = checkPresentPartitionPiecesOnCurrentShard(timeouts, *task_shard, partition_name, piece_number);
shard_partition_pieces.emplace_back(shard_partition_it->second, piece_number, res);
}
}
if (!missing_partitions.empty())
{
WriteBufferFromOwnString ss;
for (const String & missing_partition : missing_partitions)
ss << " " << missing_partition;
LOG_WARNING(log, "There are no {} partitions from enabled_partitions in shard {} :{}", missing_partitions.size(), task_shard->getDescription(), ss.str());
}
LOG_INFO(log, "Will copy {} partitions from shard {}", task_shard->partition_tasks.size(), task_shard->getDescription());
}
void ClusterCopier::discoverTablePartitions(const ConnectionTimeouts & timeouts, TaskTable & task_table, UInt64 num_threads)
{
/// Fetch partitions list from a shard
{
ThreadPool thread_pool(num_threads ? num_threads : 2 * getNumberOfPhysicalCPUCores());
for (const TaskShardPtr & task_shard : task_table.all_shards)
thread_pool.scheduleOrThrowOnError([this, timeouts, task_shard]()
{
setThreadName("DiscoverPartns");
discoverShardPartitions(timeouts, task_shard);
});
LOG_INFO(log, "Waiting for {} setup jobs", thread_pool.active());
thread_pool.wait();
}
}
void ClusterCopier::uploadTaskDescription(const std::string & task_path, const std::string & task_file, const bool force)
{
auto local_task_description_path = task_path + "/description";
String task_config_str;
{
ReadBufferFromFile in(task_file);
readStringUntilEOF(task_config_str, in);
}
if (task_config_str.empty())
return;
auto zookeeper = getContext()->getZooKeeper();
zookeeper->createAncestors(local_task_description_path);
auto code = zookeeper->tryCreate(local_task_description_path, task_config_str, zkutil::CreateMode::Persistent);
if (code != Coordination::Error::ZOK && force)
zookeeper->createOrUpdate(local_task_description_path, task_config_str, zkutil::CreateMode::Persistent);
LOG_INFO(log, "Task description {} uploaded to {} with result {} ({})",
((code != Coordination::Error::ZOK && !force) ? "not " : ""), local_task_description_path, code, Coordination::errorMessage(code));
}
void ClusterCopier::reloadTaskDescription()
{
auto zookeeper = getContext()->getZooKeeper();
task_description_watch_zookeeper = zookeeper;
Coordination::Stat stat{};
/// It will throw exception if such a node doesn't exist.
auto task_config_str = zookeeper->get(task_description_path, &stat);
LOG_INFO(log, "Loading task description");
task_cluster_current_config = getConfigurationFromXMLString(task_config_str);
/// Setup settings
task_cluster->reloadSettings(*task_cluster_current_config);
getContext()->setSettings(task_cluster->settings_common);
}
void ClusterCopier::updateConfigIfNeeded()
{
UInt64 version_to_update = task_description_version;
bool is_outdated_version = task_description_current_version != version_to_update;
bool is_expired_session = !task_description_watch_zookeeper || task_description_watch_zookeeper->expired();
if (!is_outdated_version && !is_expired_session)
return;
LOG_INFO(log, "Updating task description");
reloadTaskDescription();
task_description_current_version = version_to_update;
}
void ClusterCopier::process(const ConnectionTimeouts & timeouts)
{
for (TaskTable & task_table : task_cluster->table_tasks)
{
LOG_INFO(log, "Process table task {} with {} shards, {} of them are local ones", task_table.table_id, task_table.all_shards.size(), task_table.local_shards.size());
if (task_table.all_shards.empty())
continue;
/// Discover partitions of each shard and total set of partitions
if (!task_table.has_enabled_partitions)
{
/// If there are no specified enabled_partitions, we must discover them manually
discoverTablePartitions(timeouts, task_table);
/// After partitions of each shard are initialized, initialize cluster partitions
for (const TaskShardPtr & task_shard : task_table.all_shards)
{
for (const auto & partition_elem : task_shard->partition_tasks)
{
const String & partition_name = partition_elem.first;
task_table.cluster_partitions.emplace(partition_name, ClusterPartition{});
}
}
for (auto & partition_elem : task_table.cluster_partitions)
{
const String & partition_name = partition_elem.first;
for (const TaskShardPtr & task_shard : task_table.all_shards)
task_shard->checked_partitions.emplace(partition_name);
task_table.ordered_partition_names.emplace_back(partition_name);
}
}
else
{
/// If enabled_partitions are specified, assume that each shard has all partitions
/// We will refine partition set of each shard in future
for (const String & partition_name : task_table.enabled_partitions)
{
task_table.cluster_partitions.emplace(partition_name, ClusterPartition{});
task_table.ordered_partition_names.emplace_back(partition_name);
}
}
task_table.watch.restart();
/// Retry table processing
bool table_is_done = false;
for (UInt64 num_table_tries = 1; num_table_tries <= max_table_tries; ++num_table_tries)
{
if (tryProcessTable(timeouts, task_table))
{
table_is_done = true;
break;
}
}
if (!table_is_done)
{
throw Exception("Too many tries to process table " + task_table.table_id + ". Abort remaining execution",
ErrorCodes::UNFINISHED);
}
}
}
/// Protected section
/*
* Creates task worker node and checks maximum number of workers not to exceed the limit.
* To achieve this we have to check version of workers_version_path node and create current_worker_path
* node atomically.
* */
zkutil::EphemeralNodeHolder::Ptr ClusterCopier::createTaskWorkerNodeAndWaitIfNeed(
const zkutil::ZooKeeperPtr & zookeeper,
const String & description,
bool unprioritized)
{
std::chrono::milliseconds current_sleep_time = retry_delay_ms;
static constexpr std::chrono::milliseconds max_sleep_time(30000); // 30 sec
if (unprioritized)
std::this_thread::sleep_for(current_sleep_time);
String workers_version_path = getWorkersPathVersion();
String workers_path = getWorkersPath();
String current_worker_path = getCurrentWorkerNodePath();
UInt64 num_bad_version_errors = 0;
while (true)
{
updateConfigIfNeeded();
Coordination::Stat stat;
zookeeper->get(workers_version_path, &stat);
auto version = stat.version;
zookeeper->get(workers_path, &stat);
if (static_cast<UInt64>(stat.numChildren) >= task_cluster->max_workers)
{
LOG_INFO(log, "Too many workers ({}, maximum {}). Postpone processing {}", stat.numChildren, task_cluster->max_workers, description);
if (unprioritized)
current_sleep_time = std::min(max_sleep_time, current_sleep_time + retry_delay_ms);
std::this_thread::sleep_for(current_sleep_time);
num_bad_version_errors = 0;
}
else
{
Coordination::Requests ops;
ops.emplace_back(zkutil::makeSetRequest(workers_version_path, description, version));
ops.emplace_back(zkutil::makeCreateRequest(current_worker_path, description, zkutil::CreateMode::Ephemeral));
Coordination::Responses responses;
auto code = zookeeper->tryMulti(ops, responses);
if (code == Coordination::Error::ZOK || code == Coordination::Error::ZNODEEXISTS)
return std::make_shared<zkutil::EphemeralNodeHolder>(current_worker_path, *zookeeper, false, false, description);
if (code == Coordination::Error::ZBADVERSION)
{
++num_bad_version_errors;
/// Try to make fast retries
if (num_bad_version_errors > 3)
{
LOG_INFO(log, "A concurrent worker has just been added, will check free worker slots again");
std::chrono::milliseconds random_sleep_time(std::uniform_int_distribution<int>(1, 1000)(task_cluster->random_engine));
std::this_thread::sleep_for(random_sleep_time);
num_bad_version_errors = 0;
}
}
else
throw Coordination::Exception(code);
}
}
}
bool ClusterCopier::checkPartitionPieceIsClean(
const zkutil::ZooKeeperPtr & zookeeper,
const CleanStateClock & clean_state_clock,
const String & task_status_path)
{
LogicalClock task_start_clock;
Coordination::Stat stat{};
if (zookeeper->exists(task_status_path, &stat))
task_start_clock = LogicalClock(stat.mzxid);
return clean_state_clock.is_clean() && (!task_start_clock.hasHappened() || clean_state_clock.discovery_zxid <= task_start_clock);
}
bool ClusterCopier::checkAllPiecesInPartitionAreDone(const TaskTable & task_table, const String & partition_name, const TasksShard & shards_with_partition)
{
bool answer = true;
for (size_t piece_number = 0; piece_number < task_table.number_of_splits; ++piece_number)
{
bool piece_is_done = checkPartitionPieceIsDone(task_table, partition_name, piece_number, shards_with_partition);
if (!piece_is_done)
LOG_INFO(log, "Partition {} piece {} is not already done.", partition_name, piece_number);
answer &= piece_is_done;
}
return answer;
}
/* The same as function above
* Assume that we don't know on which shards do we have partition certain piece.
* We'll check them all (I mean shards that contain the whole partition)
* And shards that don't have certain piece MUST mark that piece is_done true.
* */
bool ClusterCopier::checkPartitionPieceIsDone(const TaskTable & task_table, const String & partition_name,
size_t piece_number, const TasksShard & shards_with_partition)
{
LOG_INFO(log, "Check that all shards processed partition {} piece {} successfully", partition_name, piece_number);
auto zookeeper = getContext()->getZooKeeper();
/// Collect all shards that contain partition piece number piece_number.
Strings piece_status_paths;
for (const auto & shard : shards_with_partition)
{
ShardPartition & task_shard_partition = shard->partition_tasks.find(partition_name)->second;
ShardPartitionPiece & shard_partition_piece = task_shard_partition.pieces[piece_number];
piece_status_paths.emplace_back(shard_partition_piece.getShardStatusPath());
}
std::vector<int64_t> zxid1, zxid2;
try
{
std::vector<zkutil::ZooKeeper::FutureGet> get_futures;
for (const String & path : piece_status_paths)
get_futures.emplace_back(zookeeper->asyncGet(path));
// Check that state is Finished and remember zxid
for (auto & future : get_futures)
{
auto res = future.get();
TaskStateWithOwner status = TaskStateWithOwner::fromString(res.data);
if (status.state != TaskState::Finished)
{
LOG_INFO(log, "The task {} is being rewritten by {}. Partition piece will be rechecked", res.data, status.owner);
return false;
}
zxid1.push_back(res.stat.pzxid);
}
const String piece_is_dirty_flag_path = task_table.getCertainPartitionPieceIsDirtyPath(partition_name, piece_number);
const String piece_is_dirty_cleaned_path = task_table.getCertainPartitionPieceIsCleanedPath(partition_name, piece_number);
const String piece_task_status_path = task_table.getCertainPartitionPieceTaskStatusPath(partition_name, piece_number);
CleanStateClock clean_state_clock (zookeeper, piece_is_dirty_flag_path, piece_is_dirty_cleaned_path);
const bool is_clean = checkPartitionPieceIsClean(zookeeper, clean_state_clock, piece_task_status_path);
if (!is_clean)
{
LOG_INFO(log, "Partition {} become dirty", partition_name);
return false;
}
get_futures.clear();
for (const String & path : piece_status_paths)
get_futures.emplace_back(zookeeper->asyncGet(path));
// Remember zxid of states again
for (auto & future : get_futures)
{
auto res = future.get();
zxid2.push_back(res.stat.pzxid);
}
}
catch (const Coordination::Exception & e)
{
LOG_INFO(log, "A ZooKeeper error occurred while checking partition {} piece number {}. Will recheck the partition. Error: {}", partition_name, toString(piece_number), e.displayText());
return false;
}
// If all task is finished and zxid is not changed then partition could not become dirty again
for (UInt64 shard_num = 0; shard_num < piece_status_paths.size(); ++shard_num)
{
if (zxid1[shard_num] != zxid2[shard_num])
{
LOG_INFO(log, "The task {} is being modified now. Partition piece will be rechecked", piece_status_paths[shard_num]);
return false;
}
}
LOG_INFO(log, "Partition {} piece number {} is copied successfully", partition_name, toString(piece_number));
return true;
}
TaskStatus ClusterCopier::tryMoveAllPiecesToDestinationTable(const TaskTable & task_table, const String & partition_name)
{
bool inject_fault = false;
if (move_fault_probability > 0)
{
double value = std::uniform_real_distribution<>(0, 1)(task_table.task_cluster.random_engine);
inject_fault = value < move_fault_probability;
}
LOG_INFO(log, "Try to move {} to destination table", partition_name);
auto zookeeper = getContext()->getZooKeeper();
const auto current_partition_attach_is_active = task_table.getPartitionAttachIsActivePath(partition_name);
const auto current_partition_attach_is_done = task_table.getPartitionAttachIsDonePath(partition_name);
/// Create ephemeral node to mark that we are active and process the partition
zookeeper->createAncestors(current_partition_attach_is_active);
zkutil::EphemeralNodeHolderPtr partition_attach_node_holder;
try
{
partition_attach_node_holder = zkutil::EphemeralNodeHolder::create(current_partition_attach_is_active, *zookeeper, host_id);
}
catch (const Coordination::Exception & e)
{
if (e.code == Coordination::Error::ZNODEEXISTS)
{
LOG_INFO(log, "Someone is already moving pieces {}", current_partition_attach_is_active);
return TaskStatus::Active;
}
throw;
}
/// Exit if task has been already processed;
/// create blocking node to signal cleaning up if it is abandoned
{
String status_data;
if (zookeeper->tryGet(current_partition_attach_is_done, status_data))
{
TaskStateWithOwner status = TaskStateWithOwner::fromString(status_data);
if (status.state == TaskState::Finished)
{
LOG_INFO(log, "All pieces for partition from this task {} has been successfully moved to destination table by {}", current_partition_attach_is_active, status.owner);
return TaskStatus::Finished;
}
/// Task is abandoned, because previously we created ephemeral node, possibly in other copier's process.
/// Initialize DROP PARTITION
LOG_INFO(log, "Moving piece for partition {} has not been successfully finished by {}. Will try to move by myself.", current_partition_attach_is_active, status.owner);
/// Remove is_done marker.
zookeeper->remove(current_partition_attach_is_done);
}
}
/// Try start processing, create node about it
{
String start_state = TaskStateWithOwner::getData(TaskState::Started, host_id);
zookeeper->create(current_partition_attach_is_done, start_state, zkutil::CreateMode::Persistent);
}
/// Try to drop destination partition in original table
if (task_table.allow_to_drop_target_partitions)
{
DatabaseAndTableName original_table = task_table.table_push;
WriteBufferFromOwnString ss;
ss << "ALTER TABLE " << getQuotedTable(original_table) << ((partition_name == "'all'") ? " DROP PARTITION ID " : " DROP PARTITION ") << partition_name;
UInt64 num_shards_drop_partition = executeQueryOnCluster(task_table.cluster_push, ss.str(), task_cluster->settings_push, ClusterExecutionMode::ON_EACH_SHARD);
LOG_INFO(log, "Drop partition {} in original table {} have been executed successfully on {} shards of {}",
partition_name, getQuotedTable(original_table), num_shards_drop_partition, task_table.cluster_push->getShardCount());
}
/// Move partition to original destination table.
for (size_t current_piece_number = 0; current_piece_number < task_table.number_of_splits; ++current_piece_number)
{
LOG_INFO(log, "Trying to move partition {} piece {} to original table", partition_name, toString(current_piece_number));
ASTPtr query_alter_ast;
String query_alter_ast_string;
DatabaseAndTableName original_table = task_table.table_push;
DatabaseAndTableName helping_table = DatabaseAndTableName(original_table.first,
original_table.second + "_piece_" +
toString(current_piece_number));
Settings settings_push = task_cluster->settings_push;
ClusterExecutionMode execution_mode = ClusterExecutionMode::ON_EACH_NODE;
if (settings_push.replication_alter_partitions_sync == 1)
execution_mode = ClusterExecutionMode::ON_EACH_SHARD;
query_alter_ast_string += " ALTER TABLE " + getQuotedTable(original_table) +
((partition_name == "'all'") ? " ATTACH PARTITION ID " : " ATTACH PARTITION ") + partition_name +
" FROM " + getQuotedTable(helping_table);
LOG_INFO(log, "Executing ALTER query: {}", query_alter_ast_string);
try
{
/// Try attach partition on each shard
UInt64 num_nodes = executeQueryOnCluster(
task_table.cluster_push,
query_alter_ast_string,
task_cluster->settings_push,
execution_mode);
if (settings_push.replication_alter_partitions_sync == 1)
{
LOG_INFO(
log,
"Destination tables {} have been executed alter query successfully on {} shards of {}",
getQuotedTable(task_table.table_push),
num_nodes,
task_table.cluster_push->getShardCount());
if (num_nodes != task_table.cluster_push->getShardCount())
return TaskStatus::Error;
}
else
{
LOG_INFO(log, "Number of nodes that executed ALTER query successfully : {}", toString(num_nodes));
}
}
catch (...)
{
LOG_INFO(log, "Error while moving partition {} piece {} to original table", partition_name, toString(current_piece_number));
LOG_WARNING(log, "In case of non-replicated tables it can cause duplicates.");
throw;
}
if (inject_fault)
throw Exception("Copy fault injection is activated", ErrorCodes::UNFINISHED);
}
/// Create node to signal that we finished moving
{
String state_finished = TaskStateWithOwner::getData(TaskState::Finished, host_id);
zookeeper->set(current_partition_attach_is_done, state_finished, 0);
/// Also increment a counter of processed partitions
while (true)
{
Coordination::Stat stat;
auto status_json = zookeeper->get(task_zookeeper_path + "/status", &stat);
auto statuses = StatusAccumulator::fromJSON(status_json);
/// Increment status for table.
auto status_for_table = (*statuses)[task_table.name_in_config];
status_for_table.processed_partitions_count += 1;
(*statuses)[task_table.name_in_config] = status_for_table;
auto statuses_to_commit = StatusAccumulator::serializeToJSON(statuses);
auto error = zookeeper->trySet(task_zookeeper_path + "/status", statuses_to_commit, stat.version, &stat);
if (error == Coordination::Error::ZOK)
break;
}
}
return TaskStatus::Finished;
}
/// This is needed to create internal Distributed table
/// Removes column's TTL expression from `CREATE` query
/// Removes MATEREALIZED or ALIAS columns not to copy additional and useless data over the network.
/// Removes data skipping indices.
ASTPtr ClusterCopier::removeAliasMaterializedAndTTLColumnsFromCreateQuery(const ASTPtr & query_ast, bool allow_to_copy_alias_and_materialized_columns)
{
const ASTs & column_asts = query_ast->as<ASTCreateQuery &>().columns_list->columns->children;
auto new_columns = std::make_shared<ASTExpressionList>();
for (const ASTPtr & column_ast : column_asts)
{
const auto & column = column_ast->as<ASTColumnDeclaration &>();
/// Skip this columns
if (!column.default_specifier.empty() && !allow_to_copy_alias_and_materialized_columns)
{
ColumnDefaultKind kind = columnDefaultKindFromString(column.default_specifier);
if (kind == ColumnDefaultKind::Materialized || kind == ColumnDefaultKind::Alias)
continue;
}
/// Remove TTL on columns definition.
auto new_column_ast = column_ast->clone();
auto & new_column = new_column_ast->as<ASTColumnDeclaration &>();
if (new_column.ttl)
new_column.ttl.reset();
new_columns->children.emplace_back(new_column_ast);
}
ASTPtr new_query_ast = query_ast->clone();
auto & new_query = new_query_ast->as<ASTCreateQuery &>();
auto new_columns_list = std::make_shared<ASTColumns>();
new_columns_list->set(new_columns_list->columns, new_columns);
/// Skip indices and projections are not needed, because distributed table doesn't support it.
new_query.replace(new_query.columns_list, new_columns_list);
return new_query_ast;
}
/// Replaces ENGINE and table name in a create query
std::shared_ptr<ASTCreateQuery> rewriteCreateQueryStorage(const ASTPtr & create_query_ast,
const DatabaseAndTableName & new_table,
const ASTPtr & new_storage_ast)
{
const auto & create = create_query_ast->as<ASTCreateQuery &>();
auto res = std::make_shared<ASTCreateQuery>(create);
if (create.storage == nullptr || new_storage_ast == nullptr)
throw Exception("Storage is not specified", ErrorCodes::LOGICAL_ERROR);
res->setDatabase(new_table.first);
res->setTable(new_table.second);
res->children.clear();
res->set(res->columns_list, create.columns_list->clone());
res->set(res->storage, new_storage_ast->clone());
/// Just to make it better and don't store additional flag like `is_table_created` somewhere else
res->if_not_exists = true;
return res;
}
bool ClusterCopier::tryDropPartitionPiece(
ShardPartition & task_partition,
const size_t current_piece_number,
const zkutil::ZooKeeperPtr & zookeeper,
const CleanStateClock & clean_state_clock)
{
if (is_safe_mode)
throw Exception("DROP PARTITION is prohibited in safe mode", ErrorCodes::NOT_IMPLEMENTED);
TaskTable & task_table = task_partition.task_shard.task_table;
ShardPartitionPiece & partition_piece = task_partition.pieces[current_piece_number];
const String current_shards_path = partition_piece.getPartitionPieceShardsPath();
const String current_partition_active_workers_dir = partition_piece.getPartitionPieceActiveWorkersPath();
const String is_dirty_flag_path = partition_piece.getPartitionPieceIsDirtyPath();
const String dirty_cleaner_path = partition_piece.getPartitionPieceCleanerPath();
const String is_dirty_cleaned_path = partition_piece.getPartitionPieceIsCleanedPath();
zkutil::EphemeralNodeHolder::Ptr cleaner_holder;
try
{
cleaner_holder = zkutil::EphemeralNodeHolder::create(dirty_cleaner_path, *zookeeper, host_id);
}
catch (const Coordination::Exception & e)
{
if (e.code == Coordination::Error::ZNODEEXISTS)
{
LOG_INFO(log, "Partition {} piece {} is cleaning now by somebody, sleep", task_partition.name, toString(current_piece_number));
std::this_thread::sleep_for(retry_delay_ms);
return false;
}
throw;
}
Coordination::Stat stat{};
if (zookeeper->exists(current_partition_active_workers_dir, &stat))
{
if (stat.numChildren != 0)
{
LOG_INFO(log, "Partition {} contains {} active workers while trying to drop it. Going to sleep.", task_partition.name, stat.numChildren);
std::this_thread::sleep_for(retry_delay_ms);
return false;
}
else
{
zookeeper->remove(current_partition_active_workers_dir);
}
}
{
zkutil::EphemeralNodeHolder::Ptr active_workers_lock;
try
{
active_workers_lock = zkutil::EphemeralNodeHolder::create(current_partition_active_workers_dir, *zookeeper, host_id);
}
catch (const Coordination::Exception & e)
{
if (e.code == Coordination::Error::ZNODEEXISTS)
{
LOG_INFO(log, "Partition {} is being filled now by somebody, sleep", task_partition.name);
return false;
}
throw;
}
// Lock the dirty flag
zookeeper->set(is_dirty_flag_path, host_id, clean_state_clock.discovery_version.value());
zookeeper->tryRemove(partition_piece.getPartitionPieceCleanStartPath());
CleanStateClock my_clock(zookeeper, is_dirty_flag_path, is_dirty_cleaned_path);
/// Remove all status nodes
{
Strings children;
if (zookeeper->tryGetChildren(current_shards_path, children) == Coordination::Error::ZOK)
for (const auto & child : children)
{
zookeeper->removeRecursive(current_shards_path + "/" + child);
}
}
DatabaseAndTableName original_table = task_table.table_push;
DatabaseAndTableName helping_table = DatabaseAndTableName(original_table.first, original_table.second + "_piece_" + toString(current_piece_number));
String query = "ALTER TABLE " + getQuotedTable(helping_table);
query += ((task_partition.name == "'all'") ? " DROP PARTITION ID " : " DROP PARTITION ") + task_partition.name + "";
/// TODO: use this statement after servers will be updated up to 1.1.54310
// query += " DROP PARTITION ID '" + task_partition.name + "'";
ClusterPtr & cluster_push = task_table.cluster_push;
Settings settings_push = task_cluster->settings_push;
/// It is important, DROP PARTITION must be done synchronously
settings_push.replication_alter_partitions_sync = 2;
LOG_INFO(log, "Execute distributed DROP PARTITION: {}", query);
/// We have to drop partition_piece on each replica
size_t num_shards = executeQueryOnCluster(
cluster_push, query,
settings_push,
ClusterExecutionMode::ON_EACH_NODE);
LOG_INFO(log, "DROP PARTITION was successfully executed on {} nodes of a cluster.", num_shards);
/// Update the locking node
if (!my_clock.is_stale())
{
zookeeper->set(is_dirty_flag_path, host_id, my_clock.discovery_version.value());
if (my_clock.clean_state_version)
zookeeper->set(is_dirty_cleaned_path, host_id, my_clock.clean_state_version.value());
else
zookeeper->create(is_dirty_cleaned_path, host_id, zkutil::CreateMode::Persistent);
}
else
{
LOG_INFO(log, "Clean state is altered when dropping the partition, cowardly bailing");
/// clean state is stale
return false;
}
LOG_INFO(log, "Partition {} piece {} was dropped on cluster {}", task_partition.name, toString(current_piece_number), task_table.cluster_push_name);
if (zookeeper->tryCreate(current_shards_path, host_id, zkutil::CreateMode::Persistent) == Coordination::Error::ZNODEEXISTS)
zookeeper->set(current_shards_path, host_id);
}
LOG_INFO(log, "Partition {} piece {} is safe for work now.", task_partition.name, toString(current_piece_number));
return true;
}
bool ClusterCopier::tryProcessTable(const ConnectionTimeouts & timeouts, TaskTable & task_table)
{
/// Create destination table
TaskStatus task_status = TaskStatus::Error;
task_status = tryCreateDestinationTable(timeouts, task_table);
/// Exit if success
if (task_status != TaskStatus::Finished)
{
LOG_WARNING(log, "Create destination Tale Failed ");
return false;
}
/// Set all_partitions_count for table in Zookeeper
auto zookeeper = getContext()->getZooKeeper();
while (true)
{
Coordination::Stat stat;
auto status_json = zookeeper->get(task_zookeeper_path + "/status", &stat);
auto statuses = StatusAccumulator::fromJSON(status_json);
/// Exit if someone already set the initial value for this table.
if (statuses->find(task_table.name_in_config) != statuses->end())
break;
(*statuses)[task_table.name_in_config] = StatusAccumulator::TableStatus
{
/*all_partitions_count=*/task_table.ordered_partition_names.size(),
/*processed_partition_count=*/0
};
auto statuses_to_commit = StatusAccumulator::serializeToJSON(statuses);
auto error = zookeeper->trySet(task_zookeeper_path + "/status", statuses_to_commit, stat.version);
if (error == Coordination::Error::ZOK)
break;
}
/// An heuristic: if previous shard is already done, then check next one without sleeps due to max_workers constraint
bool previous_shard_is_instantly_finished = false;
/// Process each partition that is present in cluster
for (const String & partition_name : task_table.ordered_partition_names)
{
if (!task_table.cluster_partitions.count(partition_name))
throw Exception("There are no expected partition " + partition_name + ". It is a bug", ErrorCodes::LOGICAL_ERROR);
ClusterPartition & cluster_partition = task_table.cluster_partitions[partition_name];
Stopwatch watch;
/// We will check all the shards of the table and check if they contain current partition.
TasksShard expected_shards;
UInt64 num_failed_shards = 0;
++cluster_partition.total_tries;
LOG_INFO(log, "Processing partition {} for the whole cluster", partition_name);
/// Process each source shard having current partition and copy current partition
/// NOTE: shards are sorted by "distance" to current host
bool has_shard_to_process = false;
for (const TaskShardPtr & shard : task_table.all_shards)
{
/// Does shard have a node with current partition?
if (shard->partition_tasks.count(partition_name) == 0)
{
/// If not, did we check existence of that partition previously?
if (shard->checked_partitions.count(partition_name) == 0)
{
auto check_shard_has_partition = [&] () { return checkShardHasPartition(timeouts, *shard, partition_name); };
bool has_partition = retry(check_shard_has_partition);
shard->checked_partitions.emplace(partition_name);
if (has_partition)
{
const size_t number_of_splits = task_table.number_of_splits;
shard->partition_tasks.emplace(partition_name, ShardPartition(*shard, partition_name, number_of_splits));
LOG_INFO(log, "Discovered partition {} in shard {}", partition_name, shard->getDescription());
/// To save references in the future.
auto shard_partition_it = shard->partition_tasks.find(partition_name);
PartitionPieces & shard_partition_pieces = shard_partition_it->second.pieces;
for (size_t piece_number = 0; piece_number < number_of_splits; ++piece_number)
{
auto res = checkPresentPartitionPiecesOnCurrentShard(timeouts, *shard, partition_name, piece_number);
shard_partition_pieces.emplace_back(shard_partition_it->second, piece_number, res);
}
}
else
{
LOG_INFO(log, "Found that shard {} does not contain current partition {}", shard->getDescription(), partition_name);
continue;
}
}
else
{
/// We have already checked that partition, but did not discover it
previous_shard_is_instantly_finished = true;
continue;
}
}
auto it_shard_partition = shard->partition_tasks.find(partition_name);
/// Previously when we discovered that shard does not contain current partition, we skipped it.
/// At this moment partition have to be present.
if (it_shard_partition == shard->partition_tasks.end())
throw Exception("There are no such partition in a shard. This is a bug.", ErrorCodes::LOGICAL_ERROR);
auto & partition = it_shard_partition->second;
expected_shards.emplace_back(shard);
/// Do not sleep if there is a sequence of already processed shards to increase startup
bool is_unprioritized_task = !previous_shard_is_instantly_finished && shard->priority.is_remote;
task_status = TaskStatus::Error;
bool was_error = false;
has_shard_to_process = true;
for (UInt64 try_num = 1; try_num <= max_shard_partition_tries; ++try_num)
{
task_status = tryProcessPartitionTask(timeouts, partition, is_unprioritized_task);
/// Exit if success
if (task_status == TaskStatus::Finished)
break;
was_error = true;
/// Skip if the task is being processed by someone
if (task_status == TaskStatus::Active)
break;
/// Repeat on errors
std::this_thread::sleep_for(retry_delay_ms);
}
if (task_status == TaskStatus::Error)
++num_failed_shards;
previous_shard_is_instantly_finished = !was_error;
}
cluster_partition.elapsed_time_seconds += watch.elapsedSeconds();
/// Check that whole cluster partition is done
/// Firstly check the number of failed partition tasks, then look into ZooKeeper and ensure that each partition is done
bool partition_copying_is_done = num_failed_shards == 0;
try
{
partition_copying_is_done =
!has_shard_to_process
|| (partition_copying_is_done && checkAllPiecesInPartitionAreDone(task_table, partition_name, expected_shards));
}
catch (...)
{
tryLogCurrentException(log);
partition_copying_is_done = false;
}
bool partition_moving_is_done = false;
/// Try to move only if all pieces were copied.
if (partition_copying_is_done)
{
for (UInt64 try_num = 0; try_num < max_shard_partition_piece_tries_for_alter; ++try_num)
{
try
{
auto res = tryMoveAllPiecesToDestinationTable(task_table, partition_name);
/// Exit and mark current task is done.
if (res == TaskStatus::Finished)
{
partition_moving_is_done = true;
break;
}
/// Exit if this task is active.
if (res == TaskStatus::Active)
break;
/// Repeat on errors.
std::this_thread::sleep_for(retry_delay_ms);
}
catch (...)
{
tryLogCurrentException(log, "Some error occurred while moving pieces to destination table for partition " + partition_name);
}
}
}
if (partition_copying_is_done && partition_moving_is_done)
{
task_table.finished_cluster_partitions.emplace(partition_name);
task_table.bytes_copied += cluster_partition.bytes_copied;
task_table.rows_copied += cluster_partition.rows_copied;
double elapsed = cluster_partition.elapsed_time_seconds;
LOG_INFO(log, "It took {} seconds to copy partition {}: {} uncompressed bytes, {} rows and {} source blocks are copied",
elapsed, partition_name,
formatReadableSizeWithDecimalSuffix(cluster_partition.bytes_copied),
formatReadableQuantity(cluster_partition.rows_copied),
cluster_partition.blocks_copied);
if (cluster_partition.rows_copied)
{
LOG_INFO(log, "Average partition speed: {} per second.", formatReadableSizeWithDecimalSuffix(cluster_partition.bytes_copied / elapsed));
}
if (task_table.rows_copied)
{
LOG_INFO(log, "Average table {} speed: {} per second.", task_table.table_id, formatReadableSizeWithDecimalSuffix(task_table.bytes_copied / elapsed));
}
}
}
UInt64 required_partitions = task_table.cluster_partitions.size();
UInt64 finished_partitions = task_table.finished_cluster_partitions.size();
bool table_is_done = finished_partitions >= required_partitions;
if (!table_is_done)
{
LOG_INFO(log, "Table {} is not processed yet. Copied {} of {}, will retry", task_table.table_id, finished_partitions, required_partitions);
}
else
{
/// Delete helping tables in case that whole table is done
dropHelpingTables(task_table);
}
return table_is_done;
}
TaskStatus ClusterCopier::tryCreateDestinationTable(const ConnectionTimeouts & timeouts, TaskTable & task_table)
{
/// Try create original table (if not exists) on each shard
//TaskTable & task_table = task_shard.task_table;
const TaskShardPtr task_shard = task_table.all_shards.at(0);
/// We need to update table definitions for each part, it could be changed after ALTER
task_shard->current_pull_table_create_query = getCreateTableForPullShard(timeouts, *task_shard);
try
{
auto create_query_push_ast
= rewriteCreateQueryStorage(task_shard->current_pull_table_create_query, task_table.table_push, task_table.engine_push_ast);
auto & create = create_query_push_ast->as<ASTCreateQuery &>();
create.if_not_exists = true;
InterpreterCreateQuery::prepareOnClusterQuery(create, getContext(), task_table.cluster_push_name);
String query = queryToString(create_query_push_ast);
LOG_INFO(log, "Create destination tables. Query: \n {}", query);
UInt64 shards = executeQueryOnCluster(task_table.cluster_push, query, task_cluster->settings_push, ClusterExecutionMode::ON_EACH_NODE);
LOG_INFO(
log,
"Destination tables {} have been created on {} shards of {}",
getQuotedTable(task_table.table_push),
shards,
task_table.cluster_push->getShardCount());
}
catch (...)
{
tryLogCurrentException(log, "Error while creating original table. Maybe we are not first.");
}
return TaskStatus::Finished;
}
/// Job for copying partition from particular shard.
TaskStatus ClusterCopier::tryProcessPartitionTask(const ConnectionTimeouts & timeouts, ShardPartition & task_partition, bool is_unprioritized_task)
{
TaskStatus res;
try
{
res = iterateThroughAllPiecesInPartition(timeouts, task_partition, is_unprioritized_task);
}
catch (...)
{
tryLogCurrentException(log, "An error occurred while processing partition " + task_partition.name);
res = TaskStatus::Error;
}
/// At the end of each task check if the config is updated
try
{
updateConfigIfNeeded();
}
catch (...)
{
tryLogCurrentException(log, "An error occurred while updating the config");
}
return res;
}
TaskStatus ClusterCopier::iterateThroughAllPiecesInPartition(const ConnectionTimeouts & timeouts, ShardPartition & task_partition,
bool is_unprioritized_task)
{
const size_t total_number_of_pieces = task_partition.task_shard.task_table.number_of_splits;
TaskStatus res{TaskStatus::Finished};
bool was_failed_pieces = false;
bool was_active_pieces = false;
for (size_t piece_number = 0; piece_number < total_number_of_pieces; piece_number++)
{
for (UInt64 try_num = 0; try_num < max_shard_partition_tries; ++try_num)
{
LOG_INFO(log, "Attempt number {} to process partition {} piece number {} on shard number {} with index {}.",
try_num, task_partition.name, piece_number,
task_partition.task_shard.numberInCluster(),
task_partition.task_shard.indexInCluster());
res = processPartitionPieceTaskImpl(timeouts, task_partition, piece_number, is_unprioritized_task);
/// Exit if success
if (res == TaskStatus::Finished)
break;
/// Skip if the task is being processed by someone
if (res == TaskStatus::Active)
break;
/// Repeat on errors
std::this_thread::sleep_for(retry_delay_ms);
}
was_active_pieces = (res == TaskStatus::Active);
was_failed_pieces = (res == TaskStatus::Error);
}
if (was_failed_pieces)
return TaskStatus::Error;
if (was_active_pieces)
return TaskStatus::Active;
return TaskStatus::Finished;
}
TaskStatus ClusterCopier::processPartitionPieceTaskImpl(
const ConnectionTimeouts & timeouts, ShardPartition & task_partition,
const size_t current_piece_number, bool is_unprioritized_task)
{
TaskShard & task_shard = task_partition.task_shard;
TaskTable & task_table = task_shard.task_table;
ClusterPartition & cluster_partition = task_table.getClusterPartition(task_partition.name);
ShardPartitionPiece & partition_piece = task_partition.pieces[current_piece_number];
const size_t number_of_splits = task_table.number_of_splits;
const String primary_key_comma_separated = task_table.primary_key_comma_separated;
/// We need to update table definitions for each partition, it could be changed after ALTER
createShardInternalTables(timeouts, task_shard, true);
auto split_table_for_current_piece = task_shard.list_of_split_tables_on_shard[current_piece_number];
auto zookeeper = getContext()->getZooKeeper();
const String piece_is_dirty_flag_path = partition_piece.getPartitionPieceIsDirtyPath();
const String piece_is_dirty_cleaned_path = partition_piece.getPartitionPieceIsCleanedPath();
const String current_task_piece_is_active_path = partition_piece.getActiveWorkerPath();
const String current_task_piece_status_path = partition_piece.getShardStatusPath();
/// Auxiliary functions:
/// Creates is_dirty node to initialize DROP PARTITION
auto create_is_dirty_node = [&] (const CleanStateClock & clock)
{
if (clock.is_stale())
LOG_INFO(log, "Clean state clock is stale while setting dirty flag, cowardly bailing");
else if (!clock.is_clean())
LOG_INFO(log, "Thank you, Captain Obvious");
else if (clock.discovery_version)
{
LOG_INFO(log, "Updating clean state clock");
zookeeper->set(piece_is_dirty_flag_path, host_id, clock.discovery_version.value());
}
else
{
LOG_INFO(log, "Creating clean state clock");
zookeeper->create(piece_is_dirty_flag_path, host_id, zkutil::CreateMode::Persistent);
}
};
/// Returns SELECT query filtering current partition and applying user filter
auto get_select_query = [&] (const DatabaseAndTableName & from_table, const String & fields, bool enable_splitting, String limit = "")
{
String query;
query += "WITH " + task_partition.name + " AS partition_key ";
query += "SELECT " + fields + " FROM " + getQuotedTable(from_table);
if (enable_splitting && experimental_use_sample_offset)
query += " SAMPLE 1/" + toString(number_of_splits) + " OFFSET " + toString(current_piece_number) + "/" + toString(number_of_splits);
/// TODO: Bad, it is better to rewrite with ASTLiteral(partition_key_field)
query += " WHERE (" + queryToString(task_table.engine_push_partition_key_ast) + " = partition_key)";
if (enable_splitting && !experimental_use_sample_offset)
query += " AND ( cityHash64(" + primary_key_comma_separated + ") %" + toString(number_of_splits) + " = " + toString(current_piece_number) + " )";
if (!task_table.where_condition_str.empty())
query += " AND (" + task_table.where_condition_str + ")";
if (!limit.empty())
query += " LIMIT " + limit;
query += "FORMAT Native";
ParserQuery p_query(query.data() + query.size());
const auto & settings = getContext()->getSettingsRef();
return parseQuery(p_query, query, settings.max_query_size, settings.max_parser_depth);
};
/// Load balancing
auto worker_node_holder = createTaskWorkerNodeAndWaitIfNeed(zookeeper, current_task_piece_status_path, is_unprioritized_task);
LOG_INFO(log, "Processing {}", current_task_piece_status_path);
const String piece_status_path = partition_piece.getPartitionPieceShardsPath();
CleanStateClock clean_state_clock(zookeeper, piece_is_dirty_flag_path, piece_is_dirty_cleaned_path);
const bool is_clean = checkPartitionPieceIsClean(zookeeper, clean_state_clock, piece_status_path);
/// Do not start if partition piece is dirty, try to clean it
if (is_clean)
{
LOG_INFO(log, "Partition {} piece {} appears to be clean", task_partition.name, current_piece_number);
zookeeper->createAncestors(current_task_piece_status_path);
}
else
{
LOG_INFO(log, "Partition {} piece {} is dirty, try to drop it", task_partition.name, current_piece_number);
try
{
tryDropPartitionPiece(task_partition, current_piece_number, zookeeper, clean_state_clock);
}
catch (...)
{
tryLogCurrentException(log, "An error occurred when clean partition");
}
return TaskStatus::Error;
}
/// Create ephemeral node to mark that we are active and process the partition
zookeeper->createAncestors(current_task_piece_is_active_path);
zkutil::EphemeralNodeHolderPtr partition_task_node_holder;
try
{
partition_task_node_holder = zkutil::EphemeralNodeHolder::create(current_task_piece_is_active_path, *zookeeper, host_id);
}
catch (const Coordination::Exception & e)
{
if (e.code == Coordination::Error::ZNODEEXISTS)
{
LOG_INFO(log, "Someone is already processing {}", current_task_piece_is_active_path);
return TaskStatus::Active;
}
throw;
}
/// Exit if task has been already processed;
/// create blocking node to signal cleaning up if it is abandoned
{
String status_data;
if (zookeeper->tryGet(current_task_piece_status_path, status_data))
{
TaskStateWithOwner status = TaskStateWithOwner::fromString(status_data);
if (status.state == TaskState::Finished)
{
LOG_INFO(log, "Task {} has been successfully executed by {}", current_task_piece_status_path, status.owner);
return TaskStatus::Finished;
}
/// Task is abandoned, because previously we created ephemeral node, possibly in other copier's process.
/// Initialize DROP PARTITION
LOG_INFO(log, "Task {} has not been successfully finished by {}. Partition will be dropped and refilled.", current_task_piece_status_path, status.owner);
create_is_dirty_node(clean_state_clock);
return TaskStatus::Error;
}
}
/// Try create table (if not exists) on each shard
/// We have to create this table even in case that partition piece is empty
/// This is significant, because we will have simpler code
{
/// 1) Get columns description from any replica of destination cluster
/// 2) Change ENGINE, database and table name
/// 3) Create helping table on the whole destination cluster
auto & settings_push = task_cluster->settings_push;
auto connection = task_table.cluster_push->getAnyShardInfo().pool->get(timeouts, &settings_push, true);
String create_query = getRemoteCreateTable(task_shard.task_table.table_push, *connection, settings_push);
ParserCreateQuery parser_create_query;
auto create_query_ast = parseQuery(parser_create_query, create_query, settings_push.max_query_size, settings_push.max_parser_depth);
/// Define helping table database and name for current partition piece
DatabaseAndTableName database_and_table_for_current_piece
{
task_table.table_push.first,
task_table.table_push.second + "_piece_" + toString(current_piece_number)
};
auto new_engine_push_ast = task_table.engine_push_ast;
if (task_table.isReplicatedTable())
new_engine_push_ast = task_table.rewriteReplicatedCreateQueryToPlain();
/// Take columns definition from destination table, new database and table name, and new engine (non replicated variant of MergeTree)
auto create_query_push_ast = rewriteCreateQueryStorage(create_query_ast, database_and_table_for_current_piece, new_engine_push_ast);
String query = queryToString(create_query_push_ast);
LOG_INFO(log, "Create destination tables. Query: \n {}", query);
UInt64 shards = executeQueryOnCluster(task_table.cluster_push, query, task_cluster->settings_push, ClusterExecutionMode::ON_EACH_NODE);
LOG_INFO(
log,
"Destination tables {} have been created on {} shards of {}",
getQuotedTable(task_table.table_push),
shards,
task_table.cluster_push->getShardCount());
}
/// Exit if current piece is absent on this shard. Also mark it as finished, because we will check
/// whether each shard have processed each partitition (and its pieces).
if (partition_piece.is_absent_piece)
{
String state_finished = TaskStateWithOwner::getData(TaskState::Finished, host_id);
auto res = zookeeper->tryCreate(current_task_piece_status_path, state_finished, zkutil::CreateMode::Persistent);
if (res == Coordination::Error::ZNODEEXISTS)
LOG_INFO(log, "Partition {} piece {} is absent on current replica of a shard. But other replicas have already marked it as done.", task_partition.name, current_piece_number);
if (res == Coordination::Error::ZOK)
LOG_INFO(log, "Partition {} piece {} is absent on current replica of a shard. Will mark it as done. Other replicas will do the same.", task_partition.name, current_piece_number);
return TaskStatus::Finished;
}
/// Check that destination partition is empty if we are first worker
/// NOTE: this check is incorrect if pull and push tables have different partition key!
String clean_start_status;
if (!zookeeper->tryGet(partition_piece.getPartitionPieceCleanStartPath(), clean_start_status) || clean_start_status != "ok")
{
zookeeper->createIfNotExists(partition_piece.getPartitionPieceCleanStartPath(), "");
auto checker = zkutil::EphemeralNodeHolder::create(partition_piece.getPartitionPieceCleanStartPath() + "/checker",
*zookeeper, host_id);
// Maybe we are the first worker
ASTPtr query_select_ast = get_select_query(split_table_for_current_piece, "count()", /*enable_splitting*/ true);
UInt64 count;
{
auto local_context = Context::createCopy(context);
// Use pull (i.e. readonly) settings, but fetch data from destination servers
local_context->setSettings(task_cluster->settings_pull);
local_context->setSetting("skip_unavailable_shards", true);
Block block = getBlockWithAllStreamData(InterpreterFactory::get(query_select_ast, local_context)->execute().pipeline);
count = (block) ? block.safeGetByPosition(0).column->getUInt(0) : 0;
}
if (count != 0)
{
LOG_INFO(log, "Partition {} piece {}is not empty. In contains {} rows.", task_partition.name, current_piece_number, count);
Coordination::Stat stat_shards{};
zookeeper->get(partition_piece.getPartitionPieceShardsPath(), &stat_shards);
/// NOTE: partition is still fresh if dirt discovery happens before cleaning
if (stat_shards.numChildren == 0)
{
LOG_WARNING(log, "There are no workers for partition {} piece {}, but destination table contains {} rows. Partition will be dropped and refilled.", task_partition.name, toString(current_piece_number), count);
create_is_dirty_node(clean_state_clock);
return TaskStatus::Error;
}
}
zookeeper->set(partition_piece.getPartitionPieceCleanStartPath(), "ok");
}
/// At this point, we need to sync that the destination table is clean
/// before any actual work
/// Try start processing, create node about it
{
String start_state = TaskStateWithOwner::getData(TaskState::Started, host_id);
CleanStateClock new_clean_state_clock(zookeeper, piece_is_dirty_flag_path, piece_is_dirty_cleaned_path);
if (clean_state_clock != new_clean_state_clock)
{
LOG_INFO(log, "Partition {} piece {} clean state changed, cowardly bailing", task_partition.name, toString(current_piece_number));
return TaskStatus::Error;
}
else if (!new_clean_state_clock.is_clean())
{
LOG_INFO(log, "Partition {} piece {} is dirty and will be dropped and refilled", task_partition.name, toString(current_piece_number));
create_is_dirty_node(new_clean_state_clock);
return TaskStatus::Error;
}
zookeeper->create(current_task_piece_status_path, start_state, zkutil::CreateMode::Persistent);
}
/// Do the copying
{
bool inject_fault = false;
if (copy_fault_probability > 0)
{
double value = std::uniform_real_distribution<>(0, 1)(task_table.task_cluster.random_engine);
inject_fault = value < copy_fault_probability;
}
// Select all fields
ASTPtr query_select_ast = get_select_query(task_shard.table_read_shard, "*", /*enable_splitting*/ true, inject_fault ? "1" : "");
LOG_INFO(log, "Executing SELECT query and pull from {} : {}", task_shard.getDescription(), queryToString(query_select_ast));
ASTPtr query_insert_ast;
{
String query;
query += "INSERT INTO " + getQuotedTable(split_table_for_current_piece) + " FORMAT Native ";
ParserQuery p_query(query.data() + query.size());
const auto & settings = getContext()->getSettingsRef();
query_insert_ast = parseQuery(p_query, query, settings.max_query_size, settings.max_parser_depth);
LOG_INFO(log, "Executing INSERT query: {}", query);
}
try
{
auto context_select = Context::createCopy(context);
context_select->setSettings(task_cluster->settings_pull);
auto context_insert = Context::createCopy(context);
context_insert->setSettings(task_cluster->settings_push);
/// Custom INSERT SELECT implementation
QueryPipeline input;
QueryPipeline output;
{
BlockIO io_select = InterpreterFactory::get(query_select_ast, context_select)->execute();
BlockIO io_insert = InterpreterFactory::get(query_insert_ast, context_insert)->execute();
output = std::move(io_insert.pipeline);
/// Add converting actions to make it possible to copy blocks with slightly different schema
const auto & select_block = io_select.pipeline.getHeader();
const auto & insert_block = output.getHeader();
auto actions_dag = ActionsDAG::makeConvertingActions(
select_block.getColumnsWithTypeAndName(),
insert_block.getColumnsWithTypeAndName(),
ActionsDAG::MatchColumnsMode::Position);
auto actions = std::make_shared<ExpressionActions>(actions_dag, ExpressionActionsSettings::fromContext(getContext()));
QueryPipelineBuilder builder;
builder.init(std::move(io_select.pipeline));
builder.addSimpleTransform([&](const Block & header)
{
return std::make_shared<ExpressionTransform>(header, actions);
});
input = QueryPipelineBuilder::getPipeline(std::move(builder));
}
/// Fail-fast optimization to abort copying when the current clean state expires
std::future<Coordination::ExistsResponse> future_is_dirty_checker;
Stopwatch watch(CLOCK_MONOTONIC_COARSE);
constexpr UInt64 check_period_milliseconds = 500;
/// Will asynchronously check that ZooKeeper connection and is_dirty flag appearing while copying data
auto cancel_check = [&] ()
{
if (zookeeper->expired())
throw Exception("ZooKeeper session is expired, cancel INSERT SELECT", ErrorCodes::UNFINISHED);
if (!future_is_dirty_checker.valid())
future_is_dirty_checker = zookeeper->asyncExists(piece_is_dirty_flag_path);
/// check_period_milliseconds should less than average insert time of single block
/// Otherwise, the insertion will slow a little bit
if (watch.elapsedMilliseconds() >= check_period_milliseconds)
{
Coordination::ExistsResponse status = future_is_dirty_checker.get();
if (status.error != Coordination::Error::ZNONODE)
{
LogicalClock dirt_discovery_epoch (status.stat.mzxid);
if (dirt_discovery_epoch == clean_state_clock.discovery_zxid)
return false;
throw Exception("Partition is dirty, cancel INSERT SELECT", ErrorCodes::UNFINISHED);
}
}
return false;
};
/// Update statistics
/// It is quite rough: bytes_copied don't take into account DROP PARTITION.
auto update_stats = [&cluster_partition] (const Block & block)
{
cluster_partition.bytes_copied += block.bytes();
cluster_partition.rows_copied += block.rows();
cluster_partition.blocks_copied += 1;
};
/// Main work is here
PullingPipelineExecutor pulling_executor(input);
PushingPipelineExecutor pushing_executor(output);
Block data;
bool is_cancelled = false;
while (pulling_executor.pull(data))
{
if (cancel_check())
{
is_cancelled = true;
pushing_executor.cancel();
pushing_executor.cancel();
break;
}
pushing_executor.push(data);
update_stats(data);
}
if (!is_cancelled)
pushing_executor.finish();
// Just in case
if (future_is_dirty_checker.valid())
future_is_dirty_checker.get();
if (inject_fault)
throw Exception("Copy fault injection is activated", ErrorCodes::UNFINISHED);
}
catch (...)
{
tryLogCurrentException(log, "An error occurred during copying, partition will be marked as dirty");
create_is_dirty_node(clean_state_clock);
return TaskStatus::Error;
}
}
LOG_INFO(log, "Partition {} piece {} copied. But not moved to original destination table.", task_partition.name, toString(current_piece_number));
/// Finalize the processing, change state of current partition task (and also check is_dirty flag)
{
String state_finished = TaskStateWithOwner::getData(TaskState::Finished, host_id);
CleanStateClock new_clean_state_clock (zookeeper, piece_is_dirty_flag_path, piece_is_dirty_cleaned_path);
if (clean_state_clock != new_clean_state_clock)
{
LOG_INFO(log, "Partition {} piece {} clean state changed, cowardly bailing", task_partition.name, toString(current_piece_number));
return TaskStatus::Error;
}
else if (!new_clean_state_clock.is_clean())
{
LOG_INFO(log, "Partition {} piece {} became dirty and will be dropped and refilled", task_partition.name, toString(current_piece_number));
create_is_dirty_node(new_clean_state_clock);
return TaskStatus::Error;
}
zookeeper->set(current_task_piece_status_path, state_finished, 0);
}
return TaskStatus::Finished;
}
void ClusterCopier::dropAndCreateLocalTable(const ASTPtr & create_ast)
{
const auto & create = create_ast->as<ASTCreateQuery &>();
dropLocalTableIfExists({create.getDatabase(), create.getTable()});
auto create_context = Context::createCopy(getContext());
InterpreterCreateQuery interpreter(create_ast, create_context);
interpreter.execute();
}
void ClusterCopier::dropLocalTableIfExists(const DatabaseAndTableName & table_name) const
{
auto drop_ast = std::make_shared<ASTDropQuery>();
drop_ast->if_exists = true;
drop_ast->setDatabase(table_name.first);
drop_ast->setTable(table_name.second);
auto drop_context = Context::createCopy(getContext());
InterpreterDropQuery interpreter(drop_ast, drop_context);
interpreter.execute();
}
void ClusterCopier::dropHelpingTablesByPieceNumber(const TaskTable & task_table, size_t current_piece_number)
{
LOG_INFO(log, "Removing helping tables piece {}", current_piece_number);
DatabaseAndTableName original_table = task_table.table_push;
DatabaseAndTableName helping_table
= DatabaseAndTableName(original_table.first, original_table.second + "_piece_" + toString(current_piece_number));
String query = "DROP TABLE IF EXISTS " + getQuotedTable(helping_table);
const ClusterPtr & cluster_push = task_table.cluster_push;
Settings settings_push = task_cluster->settings_push;
LOG_INFO(log, "Execute distributed DROP TABLE: {}", query);
/// We have to drop partition_piece on each replica
UInt64 num_nodes = executeQueryOnCluster(cluster_push, query, settings_push, ClusterExecutionMode::ON_EACH_NODE);
LOG_INFO(log, "DROP TABLE query was successfully executed on {} nodes.", toString(num_nodes));
}
void ClusterCopier::dropHelpingTables(const TaskTable & task_table)
{
LOG_INFO(log, "Removing helping tables");
for (size_t current_piece_number = 0; current_piece_number < task_table.number_of_splits; ++current_piece_number)
{
dropHelpingTablesByPieceNumber(task_table, current_piece_number);
}
}
void ClusterCopier::dropParticularPartitionPieceFromAllHelpingTables(const TaskTable & task_table, const String & partition_name)
{
LOG_INFO(log, "Try drop partition partition from all helping tables.");
for (size_t current_piece_number = 0; current_piece_number < task_table.number_of_splits; ++current_piece_number)
{
DatabaseAndTableName original_table = task_table.table_push;
DatabaseAndTableName helping_table = DatabaseAndTableName(original_table.first, original_table.second + "_piece_" + toString(current_piece_number));
String query = "ALTER TABLE " + getQuotedTable(helping_table) + ((partition_name == "'all'") ? " DROP PARTITION ID " : " DROP PARTITION ") + partition_name;
const ClusterPtr & cluster_push = task_table.cluster_push;
Settings settings_push = task_cluster->settings_push;
LOG_INFO(log, "Execute distributed DROP PARTITION: {}", query);
/// We have to drop partition_piece on each replica
UInt64 num_nodes = executeQueryOnCluster(
cluster_push, query,
settings_push,
ClusterExecutionMode::ON_EACH_NODE);
LOG_INFO(log, "DROP PARTITION query was successfully executed on {} nodes.", toString(num_nodes));
}
LOG_INFO(log, "All helping tables dropped partition {}", partition_name);
}
String ClusterCopier::getRemoteCreateTable(
const DatabaseAndTableName & table, Connection & connection, const Settings & settings)
{
auto remote_context = Context::createCopy(context);
remote_context->setSettings(settings);
String query = "SHOW CREATE TABLE " + getQuotedTable(table);
Block block = getBlockWithAllStreamData(
QueryPipeline(std::make_shared<RemoteSource>(
std::make_shared<RemoteQueryExecutor>(connection, query, InterpreterShowCreateQuery::getSampleBlock(), remote_context), false, false)));
return typeid_cast<const ColumnString &>(*block.safeGetByPosition(0).column).getDataAt(0).toString();
}
ASTPtr ClusterCopier::getCreateTableForPullShard(const ConnectionTimeouts & timeouts, TaskShard & task_shard)
{
/// Fetch and parse (possibly) new definition
auto connection_entry = task_shard.info.pool->get(timeouts, &task_cluster->settings_pull, true);
String create_query_pull_str
= getRemoteCreateTable(task_shard.task_table.table_pull, *connection_entry, task_cluster->settings_pull);
ParserCreateQuery parser_create_query;
const auto & settings = getContext()->getSettingsRef();
return parseQuery(parser_create_query, create_query_pull_str, settings.max_query_size, settings.max_parser_depth);
}
/// If it is implicitly asked to create split Distributed table for certain piece on current shard, we will do it.
void ClusterCopier::createShardInternalTables(const ConnectionTimeouts & timeouts,
TaskShard & task_shard, bool create_split)
{
TaskTable & task_table = task_shard.task_table;
/// We need to update table definitions for each part, it could be changed after ALTER
task_shard.current_pull_table_create_query = getCreateTableForPullShard(timeouts, task_shard);
/// Create local Distributed tables:
/// a table fetching data from current shard and a table inserting data to the whole destination cluster
String read_shard_prefix = ".read_shard_" + toString(task_shard.indexInCluster()) + ".";
String split_shard_prefix = ".split.";
task_shard.table_read_shard = DatabaseAndTableName(working_database_name, read_shard_prefix + task_table.table_id);
task_shard.main_table_split_shard = DatabaseAndTableName(working_database_name, split_shard_prefix + task_table.table_id);
for (const auto & piece_number : collections::range(0, task_table.number_of_splits))
{
task_shard.list_of_split_tables_on_shard[piece_number] =
DatabaseAndTableName(working_database_name, split_shard_prefix + task_table.table_id + "_piece_" + toString(piece_number));
}
/// Create special cluster with single shard
String shard_read_cluster_name = read_shard_prefix + task_table.cluster_pull_name;
ClusterPtr cluster_pull_current_shard = task_table.cluster_pull->getClusterWithSingleShard(task_shard.indexInCluster());
getContext()->setCluster(shard_read_cluster_name, cluster_pull_current_shard);
auto storage_shard_ast = createASTStorageDistributed(shard_read_cluster_name, task_table.table_pull.first, task_table.table_pull.second);
auto create_query_ast = removeAliasMaterializedAndTTLColumnsFromCreateQuery(
task_shard.current_pull_table_create_query,
task_table.allow_to_copy_alias_and_materialized_columns);
auto create_table_pull_ast = rewriteCreateQueryStorage(create_query_ast, task_shard.table_read_shard, storage_shard_ast);
dropAndCreateLocalTable(create_table_pull_ast);
if (create_split)
{
auto create_table_split_piece_ast = rewriteCreateQueryStorage(
create_query_ast,
task_shard.main_table_split_shard,
task_table.main_engine_split_ast);
dropAndCreateLocalTable(create_table_split_piece_ast);
/// Create auxiliary split tables for each piece
for (const auto & piece_number : collections::range(0, task_table.number_of_splits))
{
const auto & storage_piece_split_ast = task_table.auxiliary_engine_split_asts[piece_number];
create_table_split_piece_ast = rewriteCreateQueryStorage(
create_query_ast,
task_shard.list_of_split_tables_on_shard[piece_number],
storage_piece_split_ast);
dropAndCreateLocalTable(create_table_split_piece_ast);
}
}
}
std::set<String> ClusterCopier::getShardPartitions(const ConnectionTimeouts & timeouts, TaskShard & task_shard)
{
std::set<String> res;
createShardInternalTables(timeouts, task_shard, false);
TaskTable & task_table = task_shard.task_table;
const String & partition_name = queryToString(task_table.engine_push_partition_key_ast);
if (partition_name == "'all'")
{
res.emplace("'all'");
return res;
}
String query;
{
WriteBufferFromOwnString wb;
wb << "SELECT DISTINCT " << partition_name << " AS partition FROM"
<< " " << getQuotedTable(task_shard.table_read_shard) << " ORDER BY partition DESC";
query = wb.str();
}
ParserQuery parser_query(query.data() + query.size());
const auto & settings = getContext()->getSettingsRef();
ASTPtr query_ast = parseQuery(parser_query, query, settings.max_query_size, settings.max_parser_depth);
LOG_INFO(log, "Computing destination partition set, executing query: \n {}", query);
auto local_context = Context::createCopy(context);
local_context->setSettings(task_cluster->settings_pull);
Block block = getBlockWithAllStreamData(InterpreterFactory::get(query_ast, local_context)->execute().pipeline);
if (block)
{
ColumnWithTypeAndName & column = block.getByPosition(0);
task_shard.partition_key_column = column;
for (size_t i = 0; i < column.column->size(); ++i)
{
WriteBufferFromOwnString wb;
column.type->getDefaultSerialization()->serializeTextQuoted(*column.column, i, wb, FormatSettings());
res.emplace(wb.str());
}
}
LOG_INFO(log, "There are {} destination partitions in shard {}", res.size(), task_shard.getDescription());
return res;
}
bool ClusterCopier::checkShardHasPartition(const ConnectionTimeouts & timeouts,
TaskShard & task_shard, const String & partition_quoted_name)
{
createShardInternalTables(timeouts, task_shard, false);
TaskTable & task_table = task_shard.task_table;
WriteBufferFromOwnString ss;
ss << "WITH " + partition_quoted_name + " AS partition_key ";
ss << "SELECT 1 FROM " << getQuotedTable(task_shard.table_read_shard);
ss << " WHERE (" << queryToString(task_table.engine_push_partition_key_ast) << " = partition_key)";
if (!task_table.where_condition_str.empty())
ss << " AND (" << task_table.where_condition_str << ")";
ss << " LIMIT 1";
auto query = ss.str();
ParserQuery parser_query(query.data() + query.size());
const auto & settings = getContext()->getSettingsRef();
ASTPtr query_ast = parseQuery(parser_query, query, settings.max_query_size, settings.max_parser_depth);
LOG_INFO(log, "Checking shard {} for partition {} existence, executing query: \n {}",
task_shard.getDescription(), partition_quoted_name, query_ast->formatForErrorMessage());
auto local_context = Context::createCopy(context);
local_context->setSettings(task_cluster->settings_pull);
auto pipeline = InterpreterFactory::get(query_ast, local_context)->execute().pipeline;
PullingPipelineExecutor executor(pipeline);
Block block;
executor.pull(block);
return block.rows() != 0;
}
bool ClusterCopier::checkPresentPartitionPiecesOnCurrentShard(const ConnectionTimeouts & timeouts,
TaskShard & task_shard, const String & partition_quoted_name, size_t current_piece_number)
{
createShardInternalTables(timeouts, task_shard, false);
TaskTable & task_table = task_shard.task_table;
const size_t number_of_splits = task_table.number_of_splits;
const String & primary_key_comma_separated = task_table.primary_key_comma_separated;
UNUSED(primary_key_comma_separated);
std::string query;
query += "WITH " + partition_quoted_name + " AS partition_key ";
query += "SELECT 1 FROM " + getQuotedTable(task_shard.table_read_shard);
if (experimental_use_sample_offset)
query += " SAMPLE 1/" + toString(number_of_splits) + " OFFSET " + toString(current_piece_number) + "/" + toString(number_of_splits);
query += " WHERE (" + queryToString(task_table.engine_push_partition_key_ast) + " = partition_key)";
if (!experimental_use_sample_offset)
query += " AND (cityHash64(" + primary_key_comma_separated + ") % "
+ std::to_string(number_of_splits) + " = " + std::to_string(current_piece_number) + " )";
if (!task_table.where_condition_str.empty())
query += " AND (" + task_table.where_condition_str + ")";
query += " LIMIT 1";
LOG_INFO(log, "Checking shard {} for partition {} piece {} existence, executing query: \n \u001b[36m {}", task_shard.getDescription(), partition_quoted_name, std::to_string(current_piece_number), query);
ParserQuery parser_query(query.data() + query.size());
const auto & settings = getContext()->getSettingsRef();
ASTPtr query_ast = parseQuery(parser_query, query, settings.max_query_size, settings.max_parser_depth);
auto local_context = Context::createCopy(context);
local_context->setSettings(task_cluster->settings_pull);
auto pipeline = InterpreterFactory::get(query_ast, local_context)->execute().pipeline;
PullingPipelineExecutor executor(pipeline);
Block result;
executor.pull(result);
if (result.rows() != 0)
LOG_INFO(log, "Partition {} piece number {} is PRESENT on shard {}", partition_quoted_name, std::to_string(current_piece_number), task_shard.getDescription());
else
LOG_INFO(log, "Partition {} piece number {} is ABSENT on shard {}", partition_quoted_name, std::to_string(current_piece_number), task_shard.getDescription());
return result.rows() != 0;
}
/** Executes simple query (without output streams, for example DDL queries) on each shard of the cluster
* Returns number of shards for which at least one replica executed query successfully
*/
UInt64 ClusterCopier::executeQueryOnCluster(
const ClusterPtr & cluster,
const String & query,
const Settings & current_settings,
ClusterExecutionMode execution_mode) const
{
ClusterPtr cluster_for_query = cluster;
if (execution_mode == ClusterExecutionMode::ON_EACH_NODE)
cluster_for_query = cluster->getClusterWithReplicasAsShards(current_settings);
std::vector<std::shared_ptr<Connection>> connections;
connections.reserve(cluster->getShardCount());
std::atomic<UInt64> successfully_executed = 0;
for (const auto & replicas : cluster_for_query->getShardsAddresses())
{
for (const auto & node : replicas)
{
try
{
connections.emplace_back(std::make_shared<Connection>(
node.host_name, node.port, node.default_database,
node.user, node.password, node.cluster, node.cluster_secret,
"ClusterCopier", node.compression, node.secure
));
/// We execute only Alter, Create and Drop queries.
const auto header = Block{};
/// For unknown reason global context is passed to IStorage::read() method
/// So, task_identifier is passed as constructor argument. It is more obvious.
auto remote_query_executor = std::make_shared<RemoteQueryExecutor>(
*connections.back(), query, header, getContext(),
/*throttler=*/nullptr, Scalars(), Tables(), QueryProcessingStage::Complete);
try
{
remote_query_executor->sendQuery();
}
catch (...)
{
LOG_WARNING(log, "Node with address {} seems to be unreachable.", node.host_name);
continue;
}
while (true)
{
auto block = remote_query_executor->read();
if (!block)
break;
}
remote_query_executor->finish();
++successfully_executed;
break;
}
catch (...)
{
LOG_WARNING(log, "An error occurred while processing query : \n {}", query);
tryLogCurrentException(log);
continue;
}
}
}
return successfully_executed.load();
}
}
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