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ClickHouse/src/Databases/DatabaseReplicated.cpp
Alexey Milovidov 6a4409200e DatabaseReplicated: too much success
2024-01-01 22:01:25 +01:00

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#include <DataTypes/DataTypeString.h>
#include <utility>
#include <Backups/IRestoreCoordination.h>
#include <Backups/RestorerFromBackup.h>
#include <base/chrono_io.h>
#include <base/getFQDNOrHostName.h>
#include <Common/Exception.h>
#include <Common/Macros.h>
#include <Common/OpenTelemetryTraceContext.h>
#include <Common/ZooKeeper/KeeperException.h>
#include <Common/ZooKeeper/Types.h>
#include <Common/ZooKeeper/ZooKeeper.h>
#include <Common/PoolId.h>
#include <Databases/DatabaseFactory.h>
#include <Databases/DatabaseReplicated.h>
#include <Databases/DatabaseReplicatedWorker.h>
#include <Databases/DDLDependencyVisitor.h>
#include <Databases/TablesDependencyGraph.h>
#include <Interpreters/Cluster.h>
#include <Interpreters/Context.h>
#include <Interpreters/DDLTask.h>
#include <Interpreters/evaluateConstantExpression.h>
#include <Interpreters/executeDDLQueryOnCluster.h>
#include <Interpreters/executeQuery.h>
#include <Interpreters/InterpreterCreateQuery.h>
#include <IO/ReadBufferFromFile.h>
#include <IO/ReadBufferFromString.h>
#include <IO/ReadHelpers.h>
#include <IO/WriteHelpers.h>
#include <Parsers/ASTAlterQuery.h>
#include <Parsers/ASTDropQuery.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTDeleteQuery.h>
#include <Parsers/formatAST.h>
#include <Parsers/parseQuery.h>
#include <Parsers/ParserCreateQuery.h>
#include <Parsers/queryToString.h>
#include <Storages/StorageKeeperMap.h>
#include <Storages/AlterCommands.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NO_ZOOKEEPER;
extern const int LOGICAL_ERROR;
extern const int BAD_ARGUMENTS;
extern const int REPLICA_ALREADY_EXISTS;
extern const int DATABASE_REPLICATION_FAILED;
extern const int UNKNOWN_DATABASE;
extern const int UNKNOWN_TABLE;
extern const int NOT_IMPLEMENTED;
extern const int INCORRECT_QUERY;
extern const int ALL_CONNECTION_TRIES_FAILED;
extern const int NO_ACTIVE_REPLICAS;
extern const int CANNOT_GET_REPLICATED_DATABASE_SNAPSHOT;
extern const int CANNOT_RESTORE_TABLE;
}
static constexpr const char * REPLICATED_DATABASE_MARK = "DatabaseReplicated";
static constexpr const char * DROPPED_MARK = "DROPPED";
static constexpr const char * BROKEN_TABLES_SUFFIX = "_broken_tables";
static constexpr const char * BROKEN_REPLICATED_TABLES_SUFFIX = "_broken_replicated_tables";
static constexpr size_t METADATA_FILE_BUFFER_SIZE = 32768;
zkutil::ZooKeeperPtr DatabaseReplicated::getZooKeeper() const
{
return getContext()->getZooKeeper();
}
static inline String getHostID(ContextPtr global_context, const UUID & db_uuid)
{
return Cluster::Address::toString(getFQDNOrHostName(), global_context->getTCPPort()) + ':' + toString(db_uuid);
}
static inline UInt64 getMetadataHash(const String & table_name, const String & metadata)
{
SipHash hash;
hash.update(table_name);
hash.update(metadata);
return hash.get64();
}
DatabaseReplicated::~DatabaseReplicated() = default;
DatabaseReplicated::DatabaseReplicated(
const String & name_,
const String & metadata_path_,
UUID uuid,
const String & zookeeper_path_,
const String & shard_name_,
const String & replica_name_,
DatabaseReplicatedSettings db_settings_,
ContextPtr context_)
: DatabaseAtomic(name_, metadata_path_, uuid, "DatabaseReplicated (" + name_ + ")", context_)
, zookeeper_path(zookeeper_path_)
, shard_name(shard_name_)
, replica_name(replica_name_)
, db_settings(std::move(db_settings_))
, tables_metadata_digest(0)
{
if (zookeeper_path.empty() || shard_name.empty() || replica_name.empty())
throw Exception(ErrorCodes::BAD_ARGUMENTS, "ZooKeeper path, shard and replica names must be non-empty");
if (shard_name.find('/') != std::string::npos || replica_name.find('/') != std::string::npos)
throw Exception(ErrorCodes::BAD_ARGUMENTS, "Shard and replica names should not contain '/'");
if (shard_name.find('|') != std::string::npos || replica_name.find('|') != std::string::npos)
throw Exception(ErrorCodes::BAD_ARGUMENTS, "Shard and replica names should not contain '|'");
if (zookeeper_path.back() == '/')
zookeeper_path.resize(zookeeper_path.size() - 1);
/// If zookeeper chroot prefix is used, path should start with '/', because chroot concatenates without it.
if (zookeeper_path.front() != '/')
zookeeper_path = "/" + zookeeper_path;
if (!db_settings.collection_name.value.empty())
fillClusterAuthInfo(db_settings.collection_name.value, context_->getConfigRef());
replica_group_name = context_->getConfigRef().getString("replica_group_name", "");
}
String DatabaseReplicated::getFullReplicaName(const String & shard, const String & replica)
{
return shard + '|' + replica;
}
String DatabaseReplicated::getFullReplicaName() const
{
return getFullReplicaName(shard_name, replica_name);
}
std::pair<String, String> DatabaseReplicated::parseFullReplicaName(const String & name)
{
String shard;
String replica;
auto pos = name.find('|');
if (pos == std::string::npos || name.find('|', pos + 1) != std::string::npos)
throw Exception(ErrorCodes::LOGICAL_ERROR, "Incorrect replica identifier: {}", name);
shard = name.substr(0, pos);
replica = name.substr(pos + 1);
return {shard, replica};
}
ClusterPtr DatabaseReplicated::tryGetCluster() const
{
std::lock_guard lock{mutex};
if (cluster)
return cluster;
/// Database is probably not created or not initialized yet, it's ok to return nullptr
if (is_readonly)
return cluster;
try
{
/// A quick fix for stateless tests with DatabaseReplicated. Its ZK
/// node can be destroyed at any time. If another test lists
/// system.clusters to get client command line suggestions, it will
/// get an error when trying to get the info about DB from ZK.
/// Just ignore these inaccessible databases. A good example of a
/// failing test is `01526_client_start_and_exit`.
cluster = getClusterImpl();
}
catch (...)
{
tryLogCurrentException(log);
}
return cluster;
}
void DatabaseReplicated::setCluster(ClusterPtr && new_cluster)
{
std::lock_guard lock{mutex};
cluster = std::move(new_cluster);
}
ClusterPtr DatabaseReplicated::getClusterImpl() const
{
Strings unfiltered_hosts;
Strings hosts;
Strings host_ids;
auto zookeeper = getContext()->getZooKeeper();
constexpr int max_retries = 10;
int iteration = 0;
bool success = false;
while (++iteration <= max_retries)
{
host_ids.resize(0);
Coordination::Stat stat;
unfiltered_hosts = zookeeper->getChildren(zookeeper_path + "/replicas", &stat);
if (unfiltered_hosts.empty())
throw Exception(ErrorCodes::NO_ACTIVE_REPLICAS, "No replicas of database {} found. "
"It's possible if the first replica is not fully created yet "
"or if the last replica was just dropped or due to logical error", zookeeper_path);
hosts.clear();
std::vector<String> paths;
for (const auto & host : unfiltered_hosts)
paths.push_back(zookeeper_path + "/replicas/" + host + "/replica_group");
auto replica_groups = zookeeper->tryGet(paths);
for (size_t i = 0; i < paths.size(); ++i)
{
if (replica_groups[i].data == replica_group_name)
hosts.push_back(unfiltered_hosts[i]);
}
Int32 cversion = stat.cversion;
::sort(hosts.begin(), hosts.end());
std::vector<zkutil::ZooKeeper::FutureGet> futures;
futures.reserve(hosts.size());
host_ids.reserve(hosts.size());
for (const auto & host : hosts)
futures.emplace_back(zookeeper->asyncTryGet(zookeeper_path + "/replicas/" + host));
success = true;
for (auto & future : futures)
{
auto res = future.get();
if (res.error != Coordination::Error::ZOK)
success = false;
host_ids.emplace_back(res.data);
}
zookeeper->get(zookeeper_path + "/replicas", &stat);
if (cversion != stat.cversion)
success = false;
if (success)
break;
}
if (!success)
throw Exception(ErrorCodes::ALL_CONNECTION_TRIES_FAILED, "Cannot get consistent cluster snapshot,"
"because replicas are created or removed concurrently");
LOG_TRACE(log, "Got a list of hosts after {} iterations. All hosts: [{}], filtered: [{}], ids: [{}]", iteration,
fmt::join(unfiltered_hosts, ", "), fmt::join(hosts, ", "), fmt::join(host_ids, ", "));
assert(!hosts.empty());
assert(hosts.size() == host_ids.size());
String current_shard = parseFullReplicaName(hosts.front()).first;
std::vector<std::vector<DatabaseReplicaInfo>> shards;
shards.emplace_back();
for (size_t i = 0; i < hosts.size(); ++i)
{
const auto & id = host_ids[i];
if (id == DROPPED_MARK)
continue;
auto [shard, replica] = parseFullReplicaName(hosts[i]);
auto pos = id.rfind(':');
String host_port = id.substr(0, pos);
if (shard != current_shard)
{
current_shard = shard;
if (!shards.back().empty())
shards.emplace_back();
}
String hostname = unescapeForFileName(host_port);
shards.back().push_back(DatabaseReplicaInfo{std::move(hostname), std::move(shard), std::move(replica)});
}
UInt16 default_port;
if (cluster_auth_info.cluster_secure_connection)
default_port = getContext()->getTCPPortSecure().value_or(DBMS_DEFAULT_SECURE_PORT);
else
default_port = getContext()->getTCPPort();
bool treat_local_as_remote = false;
bool treat_local_port_as_remote = getContext()->getApplicationType() == Context::ApplicationType::LOCAL;
ClusterConnectionParameters params{
cluster_auth_info.cluster_username,
cluster_auth_info.cluster_password,
default_port,
treat_local_as_remote,
treat_local_port_as_remote,
cluster_auth_info.cluster_secure_connection,
Priority{1},
TSA_SUPPRESS_WARNING_FOR_READ(database_name), /// FIXME
cluster_auth_info.cluster_secret};
return std::make_shared<Cluster>(getContext()->getSettingsRef(), shards, params);
}
std::vector<UInt8> DatabaseReplicated::tryGetAreReplicasActive(const ClusterPtr & cluster_) const
{
Strings paths;
const auto & addresses_with_failover = cluster_->getShardsAddresses();
const auto & shards_info = cluster_->getShardsInfo();
for (size_t shard_index = 0; shard_index < shards_info.size(); ++shard_index)
{
for (const auto & replica : addresses_with_failover[shard_index])
{
String full_name = getFullReplicaName(replica.database_shard_name, replica.database_replica_name);
paths.emplace_back(fs::path(zookeeper_path) / "replicas" / full_name / "active");
}
}
try
{
auto current_zookeeper = getZooKeeper();
auto res = current_zookeeper->exists(paths);
std::vector<UInt8> statuses;
statuses.resize(paths.size());
for (size_t i = 0; i < res.size(); ++i)
if (res[i].error == Coordination::Error::ZOK)
statuses[i] = 1;
return statuses;
}
catch (...)
{
tryLogCurrentException(log);
return {};
}
}
void DatabaseReplicated::fillClusterAuthInfo(String collection_name, const Poco::Util::AbstractConfiguration & config_ref)
{
const auto & config_prefix = fmt::format("named_collections.{}", collection_name);
if (!config_ref.has(config_prefix))
throw Exception(ErrorCodes::BAD_ARGUMENTS, "There is no collection named `{}` in config", collection_name);
cluster_auth_info.cluster_username = config_ref.getString(config_prefix + ".cluster_username", "");
cluster_auth_info.cluster_password = config_ref.getString(config_prefix + ".cluster_password", "");
cluster_auth_info.cluster_secret = config_ref.getString(config_prefix + ".cluster_secret", "");
cluster_auth_info.cluster_secure_connection = config_ref.getBool(config_prefix + ".cluster_secure_connection", false);
}
void DatabaseReplicated::tryConnectToZooKeeperAndInitDatabase(LoadingStrictnessLevel mode)
{
try
{
if (!getContext()->hasZooKeeper())
{
throw Exception(ErrorCodes::NO_ZOOKEEPER, "Can't create replicated database without ZooKeeper");
}
auto current_zookeeper = getContext()->getZooKeeper();
if (!current_zookeeper->exists(zookeeper_path))
{
/// Create new database, multiple nodes can execute it concurrently
createDatabaseNodesInZooKeeper(current_zookeeper);
}
replica_path = fs::path(zookeeper_path) / "replicas" / getFullReplicaName();
bool is_create_query = mode == LoadingStrictnessLevel::CREATE;
String replica_host_id;
if (current_zookeeper->tryGet(replica_path, replica_host_id))
{
if (replica_host_id == DROPPED_MARK && !is_create_query)
{
LOG_WARNING(log, "Database {} exists locally, but marked dropped in ZooKeeper ({}). "
"Will not try to start it up", getDatabaseName(), replica_path);
is_probably_dropped = true;
return;
}
String host_id = getHostID(getContext(), db_uuid);
if (is_create_query || replica_host_id != host_id)
{
throw Exception(
ErrorCodes::REPLICA_ALREADY_EXISTS,
"Replica {} of shard {} of replicated database at {} already exists. Replica host ID: '{}', current host ID: '{}'",
replica_name, shard_name, zookeeper_path, replica_host_id, host_id);
}
/// Check that replica_group_name in ZooKeeper matches the local one and change it if necessary.
String zk_replica_group_name;
if (!current_zookeeper->tryGet(replica_path + "/replica_group", zk_replica_group_name))
{
/// Replica groups were introduced in 23.10, so the node might not exist
current_zookeeper->create(replica_path + "/replica_group", replica_group_name, zkutil::CreateMode::Persistent);
if (!replica_group_name.empty())
createEmptyLogEntry(current_zookeeper);
}
else if (zk_replica_group_name != replica_group_name)
{
current_zookeeper->set(replica_path + "/replica_group", replica_group_name, -1);
createEmptyLogEntry(current_zookeeper);
}
}
else if (is_create_query)
{
/// Create new replica. Throws if replica with the same name already exists
createReplicaNodesInZooKeeper(current_zookeeper);
}
else
{
/// It's not CREATE query, but replica does not exist. Probably it was dropped.
/// Do not create anything, continue as readonly.
LOG_WARNING(log, "Database {} exists locally, but its replica does not exist in ZooKeeper ({}). "
"Assuming it was dropped, will not try to start it up", getDatabaseName(), replica_path);
is_probably_dropped = true;
return;
}
is_readonly = false;
}
catch (...)
{
if (mode < LoadingStrictnessLevel::FORCE_ATTACH)
throw;
/// It's server startup, ignore error.
/// Worker thread will try to setup ZooKeeper connection
tryLogCurrentException(log);
}
}
bool DatabaseReplicated::createDatabaseNodesInZooKeeper(const zkutil::ZooKeeperPtr & current_zookeeper)
{
current_zookeeper->createAncestors(zookeeper_path);
Coordination::Requests ops;
ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path, REPLICATED_DATABASE_MARK, zkutil::CreateMode::Persistent));
ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/log", "", zkutil::CreateMode::Persistent));
ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/replicas", "", zkutil::CreateMode::Persistent));
ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/counter", "", zkutil::CreateMode::Persistent));
/// We create and remove counter/cnt- node to increment sequential number of counter/ node and make log entry numbers start from 1.
/// New replicas are created with log pointer equal to 0 and log pointer is a number of the last executed entry.
/// It means that we cannot have log entry with number 0.
ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/counter/cnt-", "", zkutil::CreateMode::Persistent));
ops.emplace_back(zkutil::makeRemoveRequest(zookeeper_path + "/counter/cnt-", -1));
ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/metadata", "", zkutil::CreateMode::Persistent));
ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/max_log_ptr", "1", zkutil::CreateMode::Persistent));
ops.emplace_back(zkutil::makeCreateRequest(zookeeper_path + "/logs_to_keep", "1000", zkutil::CreateMode::Persistent));
Coordination::Responses responses;
auto res = current_zookeeper->tryMulti(ops, responses);
if (res == Coordination::Error::ZOK)
return true; /// Created new database (it's the first replica)
if (res == Coordination::Error::ZNODEEXISTS)
return false; /// Database exists, we will add new replica
/// Other codes are unexpected, will throw
zkutil::KeeperMultiException::check(res, ops, responses);
UNREACHABLE();
}
bool DatabaseReplicated::looksLikeReplicatedDatabasePath(const ZooKeeperPtr & current_zookeeper, const String & path)
{
Coordination::Stat stat;
String maybe_database_mark;
if (!current_zookeeper->tryGet(path, maybe_database_mark, &stat))
return false;
if (maybe_database_mark.starts_with(REPLICATED_DATABASE_MARK))
return true;
if (!maybe_database_mark.empty())
return false;
/// Old versions did not have REPLICATED_DATABASE_MARK. Check specific nodes exist and add mark.
Coordination::Requests ops;
ops.emplace_back(zkutil::makeCheckRequest(path + "/log", -1));
ops.emplace_back(zkutil::makeCheckRequest(path + "/replicas", -1));
ops.emplace_back(zkutil::makeCheckRequest(path + "/counter", -1));
ops.emplace_back(zkutil::makeCheckRequest(path + "/metadata", -1));
ops.emplace_back(zkutil::makeCheckRequest(path + "/max_log_ptr", -1));
ops.emplace_back(zkutil::makeCheckRequest(path + "/logs_to_keep", -1));
ops.emplace_back(zkutil::makeSetRequest(path, REPLICATED_DATABASE_MARK, stat.version));
Coordination::Responses responses;
auto res = current_zookeeper->tryMulti(ops, responses);
if (res == Coordination::Error::ZOK)
return true;
/// Recheck database mark (just in case of concurrent update).
if (!current_zookeeper->tryGet(path, maybe_database_mark, &stat))
return false;
return maybe_database_mark.starts_with(REPLICATED_DATABASE_MARK);
}
void DatabaseReplicated::createEmptyLogEntry(const ZooKeeperPtr & current_zookeeper)
{
/// On replica creation add empty entry to log. Can be used to trigger some actions on other replicas (e.g. update cluster info).
DDLLogEntry entry{};
DatabaseReplicatedDDLWorker::enqueueQueryImpl(current_zookeeper, entry, this, true);
}
bool DatabaseReplicated::waitForReplicaToProcessAllEntries(UInt64 timeout_ms)
{
if (!ddl_worker || is_probably_dropped)
return false;
return ddl_worker->waitForReplicaToProcessAllEntries(timeout_ms);
}
void DatabaseReplicated::createReplicaNodesInZooKeeper(const zkutil::ZooKeeperPtr & current_zookeeper)
{
if (!looksLikeReplicatedDatabasePath(current_zookeeper, zookeeper_path))
throw Exception(ErrorCodes::BAD_ARGUMENTS, "Cannot add new database replica: provided path {} "
"already contains some data and it does not look like Replicated database path.", zookeeper_path);
/// Write host name to replica_path, it will protect from multiple replicas with the same name
auto host_id = getHostID(getContext(), db_uuid);
for (int attempts = 10; attempts > 0; --attempts)
{
Coordination::Stat stat;
String max_log_ptr_str = current_zookeeper->get(zookeeper_path + "/max_log_ptr", &stat);
Coordination::Requests ops;
ops.emplace_back(zkutil::makeCreateRequest(replica_path, host_id, zkutil::CreateMode::Persistent));
ops.emplace_back(zkutil::makeCreateRequest(replica_path + "/log_ptr", "0", zkutil::CreateMode::Persistent));
ops.emplace_back(zkutil::makeCreateRequest(replica_path + "/digest", "0", zkutil::CreateMode::Persistent));
ops.emplace_back(zkutil::makeCreateRequest(replica_path + "/replica_group", replica_group_name, zkutil::CreateMode::Persistent));
/// In addition to creating the replica nodes, we record the max_log_ptr at the instant where
/// we declared ourself as an existing replica. We'll need this during recoverLostReplica to
/// notify other nodes that issued new queries while this node was recovering.
ops.emplace_back(zkutil::makeCheckRequest(zookeeper_path + "/max_log_ptr", stat.version));
Coordination::Responses responses;
const auto code = current_zookeeper->tryMulti(ops, responses);
if (code == Coordination::Error::ZOK)
{
max_log_ptr_at_creation = parse<UInt32>(max_log_ptr_str);
break;
}
else if (code == Coordination::Error::ZNODEEXISTS || attempts == 1)
{
/// If its our last attempt, or if the replica already exists, fail immediately.
zkutil::KeeperMultiException::check(code, ops, responses);
}
}
createEmptyLogEntry(current_zookeeper);
}
void DatabaseReplicated::beforeLoadingMetadata(ContextMutablePtr context_, LoadingStrictnessLevel mode)
{
DatabaseAtomic::beforeLoadingMetadata(context_, mode);
tryConnectToZooKeeperAndInitDatabase(mode);
}
UInt64 DatabaseReplicated::getMetadataHash(const String & table_name) const
{
return DB::getMetadataHash(table_name, readMetadataFile(table_name));
}
LoadTaskPtr DatabaseReplicated::startupDatabaseAsync(AsyncLoader & async_loader, LoadJobSet startup_after, LoadingStrictnessLevel mode)
{
auto base = DatabaseAtomic::startupDatabaseAsync(async_loader, std::move(startup_after), mode);
auto job = makeLoadJob(
base->goals(),
TablesLoaderBackgroundStartupPoolId,
fmt::format("startup Replicated database {}", getDatabaseName()),
[this] (AsyncLoader &, const LoadJobPtr &)
{
UInt64 digest = 0;
{
std::lock_guard lock{mutex};
for (const auto & table : tables)
digest += getMetadataHash(table.first);
LOG_DEBUG(log, "Calculated metadata digest of {} tables: {}", tables.size(), digest);
}
{
std::lock_guard lock{metadata_mutex};
chassert(!tables_metadata_digest);
tables_metadata_digest = digest;
}
if (is_probably_dropped)
return;
ddl_worker = std::make_unique<DatabaseReplicatedDDLWorker>(this, getContext());
ddl_worker->startup();
ddl_worker_initialized = true;
});
return startup_replicated_database_task = makeLoadTask(async_loader, {job});
}
void DatabaseReplicated::waitDatabaseStarted(bool no_throw) const
{
if (startup_replicated_database_task)
waitLoad(currentPoolOr(TablesLoaderForegroundPoolId), startup_replicated_database_task, no_throw);
}
bool DatabaseReplicated::checkDigestValid(const ContextPtr & local_context, bool debug_check /* = true */) const
{
if (debug_check)
{
/// Reduce number of debug checks
if (thread_local_rng() % 16)
return true;
}
LOG_TEST(log, "Current in-memory metadata digest: {}", tables_metadata_digest);
/// Database is probably being dropped
if (!local_context->getZooKeeperMetadataTransaction() && (!ddl_worker || !ddl_worker->isCurrentlyActive()))
return true;
UInt64 local_digest = 0;
{
std::lock_guard lock{mutex};
for (const auto & table : TSA_SUPPRESS_WARNING_FOR_READ(tables))
local_digest += getMetadataHash(table.first);
}
if (local_digest != tables_metadata_digest)
{
LOG_ERROR(log, "Digest of local metadata ({}) is not equal to in-memory digest ({})", local_digest, tables_metadata_digest);
return false;
}
/// Do not check digest in Keeper after internal subquery, it's probably not committed yet
if (local_context->isInternalSubquery())
return true;
/// Check does not make sense to check digest in Keeper during recovering
if (is_recovering)
return true;
String zk_digest = getZooKeeper()->get(replica_path + "/digest");
String local_digest_str = toString(local_digest);
if (zk_digest != local_digest_str)
{
LOG_ERROR(log, "Digest of local metadata ({}) is not equal to digest in Keeper ({})", local_digest_str, zk_digest);
return false;
}
return true;
}
void DatabaseReplicated::checkQueryValid(const ASTPtr & query, ContextPtr query_context) const
{
/// Replicas will set correct name of current database in query context (database name can be different on replicas)
if (auto * ddl_query = dynamic_cast<ASTQueryWithTableAndOutput *>(query.get()))
{
if (ddl_query->getDatabase() != getDatabaseName())
throw Exception(ErrorCodes::UNKNOWN_DATABASE, "Database was renamed");
ddl_query->database.reset();
if (auto * create = query->as<ASTCreateQuery>())
{
bool replicated_table = create->storage && create->storage->engine &&
(startsWith(create->storage->engine->name, "Replicated") || startsWith(create->storage->engine->name, "Shared"));
if (!replicated_table || !create->storage->engine->arguments)
return;
ASTs & args_ref = create->storage->engine->arguments->children;
ASTs args = args_ref;
if (args.size() < 2)
return;
/// It can be a constant expression. Try to evaluate it, ignore exception if we cannot.
bool has_expression_argument = args_ref[0]->as<ASTFunction>() || args_ref[1]->as<ASTFunction>();
if (has_expression_argument)
{
try
{
args[0] = evaluateConstantExpressionAsLiteral(args_ref[0]->clone(), query_context);
args[1] = evaluateConstantExpressionAsLiteral(args_ref[1]->clone(), query_context);
}
catch (...) // NOLINT(bugprone-empty-catch)
{
}
}
ASTLiteral * arg1 = args[0]->as<ASTLiteral>();
ASTLiteral * arg2 = args[1]->as<ASTLiteral>();
if (!arg1 || !arg2 || arg1->value.getType() != Field::Types::String || arg2->value.getType() != Field::Types::String)
return;
String maybe_path = arg1->value.get<String>();
String maybe_replica = arg2->value.get<String>();
/// Looks like it's ReplicatedMergeTree with explicit zookeeper_path and replica_name arguments.
/// Let's ensure that some macros are used.
/// NOTE: we cannot check here that substituted values will be actually different on shards and replicas.
Macros::MacroExpansionInfo info;
info.table_id = {getDatabaseName(), create->getTable(), create->uuid};
info.shard = getShardName();
info.replica = getReplicaName();
query_context->getMacros()->expand(maybe_path, info);
bool maybe_shard_macros = info.expanded_other;
info.expanded_other = false;
query_context->getMacros()->expand(maybe_replica, info);
bool maybe_replica_macros = info.expanded_other;
bool enable_functional_tests_helper = getContext()->getConfigRef().has("_functional_tests_helper_database_replicated_replace_args_macros");
if (!enable_functional_tests_helper)
{
if (query_context->getSettingsRef().database_replicated_allow_replicated_engine_arguments)
LOG_WARNING(log, "It's not recommended to explicitly specify zookeeper_path and replica_name in ReplicatedMergeTree arguments");
else
throw Exception(ErrorCodes::INCORRECT_QUERY,
"It's not allowed to specify explicit zookeeper_path and replica_name "
"for ReplicatedMergeTree arguments in Replicated database. If you really want to "
"specify them explicitly, enable setting "
"database_replicated_allow_replicated_engine_arguments.");
}
if (maybe_shard_macros && maybe_replica_macros)
return;
if (enable_functional_tests_helper && !has_expression_argument)
{
if (maybe_path.empty() || maybe_path.back() != '/')
maybe_path += '/';
args_ref[0]->as<ASTLiteral>()->value = maybe_path + "auto_{shard}";
args_ref[1]->as<ASTLiteral>()->value = maybe_replica + "auto_{replica}";
return;
}
throw Exception(ErrorCodes::INCORRECT_QUERY,
"Explicit zookeeper_path and replica_name are specified in ReplicatedMergeTree arguments. "
"If you really want to specify it explicitly, then you should use some macros "
"to distinguish different shards and replicas");
}
}
if (const auto * query_alter = query->as<ASTAlterQuery>())
{
for (const auto & command : query_alter->command_list->children)
{
if (!isSupportedAlterTypeForOnClusterDDLQuery(command->as<ASTAlterCommand&>().type))
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Unsupported type of ALTER query");
}
}
if (auto * query_drop = query->as<ASTDropQuery>())
{
if (query_drop->kind == ASTDropQuery::Kind::Detach && query_context->getSettingsRef().database_replicated_always_detach_permanently)
query_drop->permanently = true;
if (query_drop->kind == ASTDropQuery::Kind::Detach && !query_drop->permanently)
throw Exception(ErrorCodes::INCORRECT_QUERY, "DETACH TABLE is not allowed for Replicated databases. "
"Use DETACH TABLE PERMANENTLY or SYSTEM RESTART REPLICA or set "
"database_replicated_always_detach_permanently to 1");
}
}
BlockIO DatabaseReplicated::tryEnqueueReplicatedDDL(const ASTPtr & query, ContextPtr query_context, QueryFlags flags)
{
waitDatabaseStarted(false);
if (query_context->getCurrentTransaction() && query_context->getSettingsRef().throw_on_unsupported_query_inside_transaction)
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Distributed DDL queries inside transactions are not supported");
if (is_readonly)
throw Exception(ErrorCodes::NO_ZOOKEEPER, "Database is in readonly mode, because it cannot connect to ZooKeeper");
if (!flags.internal && (query_context->getClientInfo().query_kind != ClientInfo::QueryKind::INITIAL_QUERY))
throw Exception(ErrorCodes::INCORRECT_QUERY, "It's not initial query. ON CLUSTER is not allowed for Replicated database.");
checkQueryValid(query, query_context);
LOG_DEBUG(log, "Proposing query: {}", queryToString(query));
DDLLogEntry entry;
entry.query = queryToString(query);
entry.initiator = ddl_worker->getCommonHostID();
entry.setSettingsIfRequired(query_context);
entry.tracing_context = OpenTelemetry::CurrentContext();
entry.is_backup_restore = flags.distributed_backup_restore;
String node_path = ddl_worker->tryEnqueueAndExecuteEntry(entry, query_context);
Strings hosts_to_wait;
Strings unfiltered_hosts = getZooKeeper()->getChildren(zookeeper_path + "/replicas");
std::vector<String> paths;
for (const auto & host : unfiltered_hosts)
paths.push_back(zookeeper_path + "/replicas/" + host + "/replica_group");
auto replica_groups = getZooKeeper()->tryGet(paths);
for (size_t i = 0; i < paths.size(); ++i)
{
if (replica_groups[i].data == replica_group_name)
hosts_to_wait.push_back(unfiltered_hosts[i]);
}
return getDistributedDDLStatus(node_path, entry, query_context, &hosts_to_wait);
}
static UUID getTableUUIDIfReplicated(const String & metadata, ContextPtr context)
{
bool looks_like_replicated = metadata.find("Replicated") != std::string::npos;
bool looks_like_shared = metadata.find("Shared") != std::string::npos;
bool looks_like_merge_tree = metadata.find("MergeTree") != std::string::npos;
if (!(looks_like_replicated || looks_like_shared) || !looks_like_merge_tree)
return UUIDHelpers::Nil;
ParserCreateQuery parser;
auto size = context->getSettingsRef().max_query_size;
auto depth = context->getSettingsRef().max_parser_depth;
ASTPtr query = parseQuery(parser, metadata, size, depth);
const ASTCreateQuery & create = query->as<const ASTCreateQuery &>();
if (!create.storage || !create.storage->engine)
return UUIDHelpers::Nil;
if (!(startsWith(create.storage->engine->name, "Replicated") || startsWith(create.storage->engine->name, "Shared"))
|| !endsWith(create.storage->engine->name, "MergeTree"))
return UUIDHelpers::Nil;
chassert(create.uuid != UUIDHelpers::Nil);
return create.uuid;
}
void DatabaseReplicated::recoverLostReplica(const ZooKeeperPtr & current_zookeeper, UInt32 our_log_ptr, UInt32 & max_log_ptr)
{
waitDatabaseStarted(false);
is_recovering = true;
SCOPE_EXIT({ is_recovering = false; });
/// Let's compare local (possibly outdated) metadata with (most actual) metadata stored in ZooKeeper
/// and try to update the set of local tables.
/// We could drop all local tables and create the new ones just like it's new replica.
/// But it will cause all ReplicatedMergeTree tables to fetch all data parts again and data in other tables will be lost.
bool new_replica = our_log_ptr == 0;
if (new_replica)
LOG_INFO(log, "Will create new replica from log pointer {}", max_log_ptr);
else
LOG_WARNING(log, "Will recover replica with staled log pointer {} from log pointer {}", our_log_ptr, max_log_ptr);
auto table_name_to_metadata = tryGetConsistentMetadataSnapshot(current_zookeeper, max_log_ptr);
/// For ReplicatedMergeTree tables we can compare only UUIDs to ensure that it's the same table.
/// Metadata can be different, it's handled on table replication level.
/// We need to handle renamed tables only.
/// TODO maybe we should also update MergeTree SETTINGS if required?
std::unordered_map<UUID, String> zk_replicated_id_to_name;
for (const auto & zk_table : table_name_to_metadata)
{
UUID zk_replicated_id = getTableUUIDIfReplicated(zk_table.second, getContext());
if (zk_replicated_id != UUIDHelpers::Nil)
zk_replicated_id_to_name.emplace(zk_replicated_id, zk_table.first);
}
/// We will drop or move tables which exist only in local metadata
Strings tables_to_detach;
struct RenameEdge
{
String from;
String intermediate;
String to;
};
/// This is needed to generate intermediate name
String salt = toString(thread_local_rng());
std::vector<RenameEdge> replicated_tables_to_rename;
size_t total_tables = 0;
std::vector<UUID> replicated_ids;
for (auto existing_tables_it = getTablesIterator(getContext(), {}); existing_tables_it->isValid();
existing_tables_it->next(), ++total_tables)
{
String name = existing_tables_it->name();
UUID local_replicated_id = UUIDHelpers::Nil;
if (existing_tables_it->table()->supportsReplication())
{
/// Check if replicated tables have the same UUID
local_replicated_id = existing_tables_it->table()->getStorageID().uuid;
auto it = zk_replicated_id_to_name.find(local_replicated_id);
if (it != zk_replicated_id_to_name.end())
{
if (name != it->second)
{
String intermediate_name;
/// Possibly we failed to rename it on previous iteration
/// And this table was already renamed to an intermediate name
if (startsWith(name, ".rename-") && !startsWith(it->second, ".rename-"))
intermediate_name = name;
else
intermediate_name = fmt::format(".rename-{}-{}", name, sipHash64(fmt::format("{}-{}", name, salt)));
/// Need just update table name
replicated_tables_to_rename.push_back({name, intermediate_name, it->second});
}
continue;
}
}
auto in_zk = table_name_to_metadata.find(name);
if (in_zk == table_name_to_metadata.end() || in_zk->second != readMetadataFile(name))
{
/// Local table does not exist in ZooKeeper or has different metadata
tables_to_detach.emplace_back(std::move(name));
}
}
auto make_query_context = [this, current_zookeeper]()
{
auto query_context = Context::createCopy(getContext());
query_context->makeQueryContext();
query_context->setQueryKind(ClientInfo::QueryKind::SECONDARY_QUERY);
query_context->setQueryKindReplicatedDatabaseInternal();
query_context->setCurrentDatabase(getDatabaseName());
query_context->setCurrentQueryId("");
/// We will execute some CREATE queries for recovery (not ATTACH queries),
/// so we need to allow experimental features that can be used in a CREATE query
query_context->setSetting("allow_experimental_inverted_index", 1);
query_context->setSetting("allow_experimental_codecs", 1);
query_context->setSetting("allow_experimental_live_view", 1);
query_context->setSetting("allow_experimental_window_view", 1);
query_context->setSetting("allow_experimental_funnel_functions", 1);
query_context->setSetting("allow_experimental_nlp_functions", 1);
query_context->setSetting("allow_experimental_hash_functions", 1);
query_context->setSetting("allow_experimental_object_type", 1);
query_context->setSetting("allow_experimental_annoy_index", 1);
query_context->setSetting("allow_experimental_usearch_index", 1);
query_context->setSetting("allow_experimental_bigint_types", 1);
query_context->setSetting("allow_experimental_window_functions", 1);
query_context->setSetting("allow_experimental_geo_types", 1);
query_context->setSetting("allow_experimental_map_type", 1);
query_context->setSetting("allow_suspicious_low_cardinality_types", 1);
query_context->setSetting("allow_suspicious_fixed_string_types", 1);
query_context->setSetting("allow_suspicious_indices", 1);
query_context->setSetting("allow_suspicious_codecs", 1);
query_context->setSetting("allow_hyperscan", 1);
query_context->setSetting("allow_simdjson", 1);
query_context->setSetting("allow_deprecated_syntax_for_merge_tree", 1);
auto txn = std::make_shared<ZooKeeperMetadataTransaction>(current_zookeeper, zookeeper_path, false, "");
query_context->initZooKeeperMetadataTransaction(txn);
return query_context;
};
String db_name = getDatabaseName();
String to_db_name = getDatabaseName() + BROKEN_TABLES_SUFFIX;
String to_db_name_replicated = getDatabaseName() + BROKEN_REPLICATED_TABLES_SUFFIX;
if (total_tables * db_settings.max_broken_tables_ratio < tables_to_detach.size())
throw Exception(ErrorCodes::DATABASE_REPLICATION_FAILED, "Too many tables to recreate: {} of {}", tables_to_detach.size(), total_tables);
else if (!tables_to_detach.empty())
{
LOG_WARNING(log, "Will recreate {} broken tables to recover replica", tables_to_detach.size());
/// It's too dangerous to automatically drop tables, so we will move them to special database.
/// We use Ordinary engine for destination database, because it's the only way to discard table UUID
/// and make possible creation of new table with the same UUID.
String query = fmt::format("CREATE DATABASE IF NOT EXISTS {} ENGINE=Ordinary", backQuoteIfNeed(to_db_name));
auto query_context = Context::createCopy(getContext());
query_context->setSetting("allow_deprecated_database_ordinary", 1);
executeQuery(query, query_context, QueryFlags{ .internal = true });
/// But we want to avoid discarding UUID of ReplicatedMergeTree tables, because it will not work
/// if zookeeper_path contains {uuid} macro. Replicated database do not recreate replicated tables on recovery,
/// so it's ok to save UUID of replicated table.
query = fmt::format("CREATE DATABASE IF NOT EXISTS {} ENGINE=Atomic", backQuoteIfNeed(to_db_name_replicated));
query_context = Context::createCopy(getContext());
executeQuery(query, query_context, QueryFlags{ .internal = true });
}
size_t moved_tables = 0;
std::vector<UUID> dropped_tables;
size_t dropped_dictionaries = 0;
for (const auto & table_name : tables_to_detach)
{
DDLGuardPtr table_guard = DatabaseCatalog::instance().getDDLGuard(db_name, table_name);
if (getDatabaseName() != db_name)
throw Exception(ErrorCodes::UNKNOWN_DATABASE, "Database was renamed, will retry");
auto table = tryGetTable(table_name, getContext());
auto move_table_to_database = [&](const String & broken_table_name, const String & to_database_name)
{
/// Table probably stores some data. Let's move it to another database.
String to_name = fmt::format("{}_{}_{}", broken_table_name, max_log_ptr, thread_local_rng() % 1000);
LOG_DEBUG(log, "Will RENAME TABLE {} TO {}.{}", backQuoteIfNeed(broken_table_name), backQuoteIfNeed(to_database_name), backQuoteIfNeed(to_name));
assert(db_name < to_database_name);
DDLGuardPtr to_table_guard = DatabaseCatalog::instance().getDDLGuard(to_database_name, to_name);
auto to_db_ptr = DatabaseCatalog::instance().getDatabase(to_database_name);
std::lock_guard lock{metadata_mutex};
UInt64 new_digest = tables_metadata_digest;
new_digest -= getMetadataHash(broken_table_name);
DatabaseAtomic::renameTable(make_query_context(), broken_table_name, *to_db_ptr, to_name, /* exchange */ false, /* dictionary */ false);
tables_metadata_digest = new_digest;
assert(checkDigestValid(getContext()));
++moved_tables;
};
if (!table->storesDataOnDisk())
{
LOG_DEBUG(log, "Will DROP TABLE {}, because it does not store data on disk and can be safely dropped", backQuoteIfNeed(table_name));
dropped_tables.push_back(tryGetTableUUID(table_name));
dropped_dictionaries += table->isDictionary();
table->flushAndShutdown();
if (table->getName() == "MaterializedView" || table->getName() == "WindowView")
{
/// We have to drop MV inner table, so MV will not try to do it implicitly breaking some invariants.
/// Also we have to commit metadata transaction, because it's not committed by default for inner tables of MVs.
/// Yep, I hate inner tables of materialized views.
auto mv_drop_inner_table_context = make_query_context();
table->dropInnerTableIfAny(/* sync */ true, mv_drop_inner_table_context);
mv_drop_inner_table_context->getZooKeeperMetadataTransaction()->commit();
}
std::lock_guard lock{metadata_mutex};
UInt64 new_digest = tables_metadata_digest;
new_digest -= getMetadataHash(table_name);
DatabaseAtomic::dropTableImpl(make_query_context(), table_name, /* sync */ true);
tables_metadata_digest = new_digest;
assert(checkDigestValid(getContext()));
}
else if (!table->supportsReplication())
{
move_table_to_database(table_name, to_db_name);
}
else
{
move_table_to_database(table_name, to_db_name_replicated);
}
}
if (!tables_to_detach.empty())
LOG_WARNING(log, "Cleaned {} outdated objects: dropped {} dictionaries and {} tables, moved {} tables",
tables_to_detach.size(), dropped_dictionaries, dropped_tables.size() - dropped_dictionaries, moved_tables);
/// Now database is cleared from outdated tables, let's rename ReplicatedMergeTree tables to actual names
/// We have to take into account that tables names could be changed with two general queries
/// 1) RENAME TABLE. There could be multiple pairs of tables (e.g. RENAME b TO c, a TO b, c TO d)
/// But it is equal to multiple subsequent RENAMEs each of which operates only with two tables
/// 2) EXCHANGE TABLE. This query swaps two names atomically and could not be represented with two separate RENAMEs
auto rename_table = [&](String from, String to)
{
LOG_DEBUG(log, "Will RENAME TABLE {} TO {}", backQuoteIfNeed(from), backQuoteIfNeed(to));
DDLGuardPtr table_guard = DatabaseCatalog::instance().getDDLGuard(db_name, std::min(from, to));
DDLGuardPtr to_table_guard = DatabaseCatalog::instance().getDDLGuard(db_name, std::max(from, to));
std::lock_guard lock{metadata_mutex};
UInt64 new_digest = tables_metadata_digest;
String statement = readMetadataFile(from);
new_digest -= DB::getMetadataHash(from, statement);
new_digest += DB::getMetadataHash(to, statement);
DatabaseAtomic::renameTable(make_query_context(), from, *this, to, false, false);
tables_metadata_digest = new_digest;
assert(checkDigestValid(getContext()));
};
LOG_DEBUG(log, "Starting first stage of renaming process. Will rename tables to intermediate names");
for (auto & [from, intermediate, _] : replicated_tables_to_rename)
{
/// Due to some unknown failures there could be tables
/// which are already in an intermediate state
/// For them we skip the first stage
if (from == intermediate)
continue;
rename_table(from, intermediate);
}
LOG_DEBUG(log, "Starting second stage of renaming process. Will rename tables from intermediate to desired names");
for (auto & [_, intermediate, to] : replicated_tables_to_rename)
rename_table(intermediate, to);
LOG_DEBUG(log, "Renames completed successfully");
for (const auto & id : dropped_tables)
DatabaseCatalog::instance().waitTableFinallyDropped(id);
/// Create all needed tables in a proper order
TablesDependencyGraph tables_dependencies("DatabaseReplicated (" + getDatabaseName() + ")");
for (const auto & [table_name, create_table_query] : table_name_to_metadata)
{
/// Note that table_name could contain a dot inside (e.g. .inner.1234-1234-1234-1234)
/// And QualifiedTableName::parseFromString doesn't handle this.
auto qualified_name = QualifiedTableName{.database = getDatabaseName(), .table = table_name};
auto query_ast = parseQueryFromMetadataInZooKeeper(table_name, create_table_query);
tables_dependencies.addDependencies(qualified_name, getDependenciesFromCreateQuery(getContext(), qualified_name, query_ast));
}
tables_dependencies.checkNoCyclicDependencies();
auto tables_to_create = tables_dependencies.getTablesSortedByDependency();
for (const auto & table_id : tables_to_create)
{
auto table_name = table_id.getTableName();
auto metadata_it = table_name_to_metadata.find(table_name);
if (metadata_it == table_name_to_metadata.end())
{
/// getTablesSortedByDependency() may return some not existing tables or tables from other databases
LOG_WARNING(log, "Got table name {} when resolving table dependencies, "
"but database {} does not have metadata for that table. Ignoring it", table_id.getNameForLogs(), getDatabaseName());
continue;
}
const auto & create_query_string = metadata_it->second;
if (isTableExist(table_name, getContext()))
{
assert(create_query_string == readMetadataFile(table_name) || getTableUUIDIfReplicated(create_query_string, getContext()) != UUIDHelpers::Nil);
continue;
}
auto query_ast = parseQueryFromMetadataInZooKeeper(table_name, create_query_string);
LOG_INFO(log, "Executing {}", serializeAST(*query_ast));
auto create_query_context = make_query_context();
InterpreterCreateQuery(query_ast, create_query_context).execute();
}
LOG_INFO(log, "All tables are created successfully");
chassert(max_log_ptr_at_creation || our_log_ptr);
UInt32 first_entry_to_mark_finished = new_replica ? max_log_ptr_at_creation : our_log_ptr;
if (first_entry_to_mark_finished)
{
/// If the replica is new and some of the queries applied during recovery
/// where issued after the replica was created, then other nodes might be
/// waiting for this node to notify them that the query was applied.
for (UInt32 ptr = first_entry_to_mark_finished; ptr <= max_log_ptr; ++ptr)
{
auto entry_name = DDLTaskBase::getLogEntryName(ptr);
auto path = fs::path(zookeeper_path) / "log" / entry_name / "finished" / getFullReplicaName();
auto status = ExecutionStatus(0).serializeText();
auto res = current_zookeeper->tryCreate(path, status, zkutil::CreateMode::Persistent);
if (res == Coordination::Error::ZOK)
LOG_INFO(log, "Marked recovered {} as finished", entry_name);
}
}
std::lock_guard lock{metadata_mutex};
chassert(checkDigestValid(getContext()));
current_zookeeper->set(replica_path + "/digest", toString(tables_metadata_digest));
}
std::map<String, String> DatabaseReplicated::tryGetConsistentMetadataSnapshot(const ZooKeeperPtr & zookeeper, UInt32 & max_log_ptr)
{
return getConsistentMetadataSnapshotImpl(zookeeper, {}, /* max_retries= */ 10, max_log_ptr);
}
std::map<String, String> DatabaseReplicated::getConsistentMetadataSnapshotImpl(
const ZooKeeperPtr & zookeeper,
const FilterByNameFunction & filter_by_table_name,
size_t max_retries,
UInt32 & max_log_ptr) const
{
std::map<String, String> table_name_to_metadata;
size_t iteration = 0;
while (++iteration <= max_retries)
{
table_name_to_metadata.clear();
LOG_DEBUG(log, "Trying to get consistent metadata snapshot for log pointer {}", max_log_ptr);
Strings escaped_table_names;
escaped_table_names = zookeeper->getChildren(zookeeper_path + "/metadata");
if (filter_by_table_name)
std::erase_if(escaped_table_names, [&](const String & table) { return !filter_by_table_name(unescapeForFileName(table)); });
std::vector<zkutil::ZooKeeper::FutureGet> futures;
futures.reserve(escaped_table_names.size());
for (const auto & table : escaped_table_names)
futures.emplace_back(zookeeper->asyncTryGet(zookeeper_path + "/metadata/" + table));
for (size_t i = 0; i < escaped_table_names.size(); ++i)
{
auto res = futures[i].get();
if (res.error != Coordination::Error::ZOK)
break;
table_name_to_metadata.emplace(unescapeForFileName(escaped_table_names[i]), res.data);
}
UInt32 new_max_log_ptr = parse<UInt32>(zookeeper->get(zookeeper_path + "/max_log_ptr"));
if (new_max_log_ptr == max_log_ptr && escaped_table_names.size() == table_name_to_metadata.size())
break;
if (max_log_ptr < new_max_log_ptr)
{
LOG_DEBUG(log, "Log pointer moved from {} to {}, will retry", max_log_ptr, new_max_log_ptr);
max_log_ptr = new_max_log_ptr;
}
else
{
chassert(max_log_ptr == new_max_log_ptr);
chassert(escaped_table_names.size() != table_name_to_metadata.size());
LOG_DEBUG(log, "Cannot get metadata of some tables due to ZooKeeper error, will retry");
}
}
if (max_retries < iteration)
throw Exception(ErrorCodes::CANNOT_GET_REPLICATED_DATABASE_SNAPSHOT, "Cannot get consistent metadata snapshot");
LOG_DEBUG(log, "Got consistent metadata snapshot for log pointer {}", max_log_ptr);
return table_name_to_metadata;
}
ASTPtr DatabaseReplicated::parseQueryFromMetadataInZooKeeper(const String & node_name, const String & query)
{
ParserCreateQuery parser;
String description = "in ZooKeeper " + zookeeper_path + "/metadata/" + node_name;
auto ast = parseQuery(parser, query, description, 0, getContext()->getSettingsRef().max_parser_depth);
auto & create = ast->as<ASTCreateQuery &>();
if (create.uuid == UUIDHelpers::Nil || create.getTable() != TABLE_WITH_UUID_NAME_PLACEHOLDER || create.database)
throw Exception(ErrorCodes::LOGICAL_ERROR, "Got unexpected query from {}: {}", node_name, query);
bool is_materialized_view_with_inner_table = create.is_materialized_view && create.to_table_id.empty();
create.setDatabase(getDatabaseName());
create.setTable(unescapeForFileName(node_name));
create.attach = is_materialized_view_with_inner_table;
return ast;
}
void DatabaseReplicated::dropReplica(
DatabaseReplicated * database, const String & database_zookeeper_path, const String & shard, const String & replica, bool throw_if_noop)
{
assert(!database || database_zookeeper_path == database->zookeeper_path);
String full_replica_name = shard.empty() ? replica : getFullReplicaName(shard, replica);
if (full_replica_name.find('/') != std::string::npos)
throw Exception(ErrorCodes::BAD_ARGUMENTS, "Invalid replica name, '/' is not allowed: {}", full_replica_name);
auto zookeeper = Context::getGlobalContextInstance()->getZooKeeper();
String database_mark;
bool db_path_exists = zookeeper->tryGet(database_zookeeper_path, database_mark);
if (!db_path_exists && !throw_if_noop)
return;
if (database_mark != REPLICATED_DATABASE_MARK)
throw Exception(ErrorCodes::BAD_ARGUMENTS, "Path {} does not look like a path of Replicated database", database_zookeeper_path);
String database_replica_path = fs::path(database_zookeeper_path) / "replicas" / full_replica_name;
if (!zookeeper->exists(database_replica_path))
{
if (!throw_if_noop)
return;
throw Exception(ErrorCodes::BAD_ARGUMENTS, "Replica {} does not exist (database path: {})",
full_replica_name, database_zookeeper_path);
}
if (zookeeper->exists(database_replica_path + "/active"))
throw Exception(ErrorCodes::BAD_ARGUMENTS, "Replica {} is active, cannot drop it (database path: {})",
full_replica_name, database_zookeeper_path);
zookeeper->set(database_replica_path, DROPPED_MARK, -1);
/// Notify other replicas that cluster configuration was changed (if we can)
if (database)
database->createEmptyLogEntry(zookeeper);
zookeeper->tryRemoveRecursive(database_replica_path);
if (zookeeper->tryRemove(database_zookeeper_path + "/replicas") == Coordination::Error::ZOK)
{
/// It was the last replica, remove all metadata
zookeeper->tryRemoveRecursive(database_zookeeper_path);
}
}
void DatabaseReplicated::drop(ContextPtr context_)
{
if (is_probably_dropped)
{
/// Don't need to drop anything from ZooKeeper
DatabaseAtomic::drop(context_);
return;
}
waitDatabaseStarted(false);
auto current_zookeeper = getZooKeeper();
current_zookeeper->set(replica_path, DROPPED_MARK, -1);
createEmptyLogEntry(current_zookeeper);
DatabaseAtomic::drop(context_);
current_zookeeper->tryRemoveRecursive(replica_path);
/// TODO it may leave garbage in ZooKeeper if the last node lost connection here
if (current_zookeeper->tryRemove(zookeeper_path + "/replicas") == Coordination::Error::ZOK)
{
/// It was the last replica, remove all metadata
current_zookeeper->tryRemoveRecursive(zookeeper_path);
}
}
void DatabaseReplicated::stopReplication()
{
waitDatabaseStarted(/* no_throw = */ true);
if (ddl_worker)
ddl_worker->shutdown();
}
void DatabaseReplicated::shutdown()
{
stopReplication();
ddl_worker_initialized = false;
ddl_worker = nullptr;
DatabaseAtomic::shutdown();
}
void DatabaseReplicated::dropTable(ContextPtr local_context, const String & table_name, bool sync)
{
waitDatabaseStarted(false);
auto txn = local_context->getZooKeeperMetadataTransaction();
assert(!ddl_worker || !ddl_worker->isCurrentlyActive() || txn || startsWith(table_name, ".inner_id."));
if (txn && txn->isInitialQuery() && !txn->isCreateOrReplaceQuery())
{
String metadata_zk_path = zookeeper_path + "/metadata/" + escapeForFileName(table_name);
txn->addOp(zkutil::makeRemoveRequest(metadata_zk_path, -1));
}
auto table = tryGetTable(table_name, getContext());
if (table->getName() == "MaterializedView" || table->getName() == "WindowView")
{
/// Avoid recursive locking of metadata_mutex
table->dropInnerTableIfAny(sync, local_context);
}
std::lock_guard lock{metadata_mutex};
UInt64 new_digest = tables_metadata_digest;
new_digest -= getMetadataHash(table_name);
if (txn && !txn->isCreateOrReplaceQuery() && !is_recovering)
txn->addOp(zkutil::makeSetRequest(replica_path + "/digest", toString(new_digest), -1));
DatabaseAtomic::dropTableImpl(local_context, table_name, sync);
tables_metadata_digest = new_digest;
assert(checkDigestValid(local_context));
}
void DatabaseReplicated::renameTable(ContextPtr local_context, const String & table_name, IDatabase & to_database,
const String & to_table_name, bool exchange, bool dictionary)
{
auto txn = local_context->getZooKeeperMetadataTransaction();
assert(txn);
if (this != &to_database)
throw Exception(ErrorCodes::NOT_IMPLEMENTED, "Moving tables between databases is not supported for Replicated engine");
if (table_name == to_table_name)
throw Exception(ErrorCodes::INCORRECT_QUERY, "Cannot rename table to itself");
if (!isTableExist(table_name, local_context))
throw Exception(ErrorCodes::UNKNOWN_TABLE, "Table {} does not exist", table_name);
if (exchange && !to_database.isTableExist(to_table_name, local_context))
throw Exception(ErrorCodes::UNKNOWN_TABLE, "Table {} does not exist", to_table_name);
waitDatabaseStarted(false);
String statement = readMetadataFile(table_name);
String statement_to;
if (exchange)
statement_to = readMetadataFile(to_table_name);
if (txn->isInitialQuery())
{
String metadata_zk_path = zookeeper_path + "/metadata/" + escapeForFileName(table_name);
String metadata_zk_path_to = zookeeper_path + "/metadata/" + escapeForFileName(to_table_name);
if (!txn->isCreateOrReplaceQuery())
txn->addOp(zkutil::makeRemoveRequest(metadata_zk_path, -1));
if (exchange)
{
txn->addOp(zkutil::makeRemoveRequest(metadata_zk_path_to, -1));
if (!txn->isCreateOrReplaceQuery())
txn->addOp(zkutil::makeCreateRequest(metadata_zk_path, statement_to, zkutil::CreateMode::Persistent));
}
txn->addOp(zkutil::makeCreateRequest(metadata_zk_path_to, statement, zkutil::CreateMode::Persistent));
}
std::lock_guard lock{metadata_mutex};
UInt64 new_digest = tables_metadata_digest;
new_digest -= DB::getMetadataHash(table_name, statement);
new_digest += DB::getMetadataHash(to_table_name, statement);
if (exchange)
{
new_digest -= DB::getMetadataHash(to_table_name, statement_to);
new_digest += DB::getMetadataHash(table_name, statement_to);
}
if (txn && !is_recovering)
txn->addOp(zkutil::makeSetRequest(replica_path + "/digest", toString(new_digest), -1));
DatabaseAtomic::renameTable(local_context, table_name, to_database, to_table_name, exchange, dictionary);
tables_metadata_digest = new_digest;
assert(checkDigestValid(local_context));
}
void DatabaseReplicated::commitCreateTable(const ASTCreateQuery & query, const StoragePtr & table,
const String & table_metadata_tmp_path, const String & table_metadata_path,
ContextPtr query_context)
{
auto txn = query_context->getZooKeeperMetadataTransaction();
assert(!ddl_worker->isCurrentlyActive() || txn);
String statement = getObjectDefinitionFromCreateQuery(query.clone());
if (txn && txn->isInitialQuery() && !txn->isCreateOrReplaceQuery())
{
String metadata_zk_path = zookeeper_path + "/metadata/" + escapeForFileName(query.getTable());
/// zk::multi(...) will throw if `metadata_zk_path` exists
txn->addOp(zkutil::makeCreateRequest(metadata_zk_path, statement, zkutil::CreateMode::Persistent));
}
std::lock_guard lock{metadata_mutex};
UInt64 new_digest = tables_metadata_digest;
new_digest += DB::getMetadataHash(query.getTable(), statement);
if (txn && !txn->isCreateOrReplaceQuery() && !is_recovering)
txn->addOp(zkutil::makeSetRequest(replica_path + "/digest", toString(new_digest), -1));
DatabaseAtomic::commitCreateTable(query, table, table_metadata_tmp_path, table_metadata_path, query_context);
tables_metadata_digest = new_digest;
assert(checkDigestValid(query_context));
}
void DatabaseReplicated::commitAlterTable(const StorageID & table_id,
const String & table_metadata_tmp_path, const String & table_metadata_path,
const String & statement, ContextPtr query_context)
{
auto txn = query_context->getZooKeeperMetadataTransaction();
assert(!ddl_worker || !ddl_worker->isCurrentlyActive() || txn);
if (txn && txn->isInitialQuery())
{
String metadata_zk_path = zookeeper_path + "/metadata/" + escapeForFileName(table_id.table_name);
txn->addOp(zkutil::makeSetRequest(metadata_zk_path, statement, -1));
}
std::lock_guard lock{metadata_mutex};
UInt64 new_digest = tables_metadata_digest;
new_digest -= getMetadataHash(table_id.table_name);
new_digest += DB::getMetadataHash(table_id.table_name, statement);
if (txn && !is_recovering)
txn->addOp(zkutil::makeSetRequest(replica_path + "/digest", toString(new_digest), -1));
DatabaseAtomic::commitAlterTable(table_id, table_metadata_tmp_path, table_metadata_path, statement, query_context);
tables_metadata_digest = new_digest;
assert(checkDigestValid(query_context));
}
bool DatabaseReplicated::canExecuteReplicatedMetadataAlter() const
{
/// ReplicatedMergeTree may call commitAlterTable from its background threads when executing ALTER_METADATA entries.
/// It may update the metadata digest (both locally and in ZooKeeper)
/// before DatabaseReplicatedDDLWorker::initializeReplication() has finished.
/// We should not update metadata until the database is initialized.
return ddl_worker_initialized && ddl_worker->isCurrentlyActive();
}
void DatabaseReplicated::detachTablePermanently(ContextPtr local_context, const String & table_name)
{
waitDatabaseStarted(false);
auto txn = local_context->getZooKeeperMetadataTransaction();
assert(!ddl_worker->isCurrentlyActive() || txn);
if (txn && txn->isInitialQuery())
{
/// We have to remove metadata from zookeeper, because we do not distinguish permanently detached tables
/// from attached tables when recovering replica.
String metadata_zk_path = zookeeper_path + "/metadata/" + escapeForFileName(table_name);
txn->addOp(zkutil::makeRemoveRequest(metadata_zk_path, -1));
}
std::lock_guard lock{metadata_mutex};
UInt64 new_digest = tables_metadata_digest;
new_digest -= getMetadataHash(table_name);
if (txn && !is_recovering)
txn->addOp(zkutil::makeSetRequest(replica_path + "/digest", toString(new_digest), -1));
DatabaseAtomic::detachTablePermanently(local_context, table_name);
tables_metadata_digest = new_digest;
assert(checkDigestValid(local_context));
}
void DatabaseReplicated::removeDetachedPermanentlyFlag(ContextPtr local_context, const String & table_name, const String & table_metadata_path, bool attach)
{
waitDatabaseStarted(false);
auto txn = local_context->getZooKeeperMetadataTransaction();
assert(!ddl_worker->isCurrentlyActive() || txn);
if (txn && txn->isInitialQuery() && attach)
{
String metadata_zk_path = zookeeper_path + "/metadata/" + escapeForFileName(table_name);
String statement = readMetadataFile(table_name);
txn->addOp(zkutil::makeCreateRequest(metadata_zk_path, statement, zkutil::CreateMode::Persistent));
}
std::lock_guard lock{metadata_mutex};
UInt64 new_digest = tables_metadata_digest;
if (attach)
{
new_digest += getMetadataHash(table_name);
if (txn && !is_recovering)
txn->addOp(zkutil::makeSetRequest(replica_path + "/digest", toString(new_digest), -1));
}
DatabaseAtomic::removeDetachedPermanentlyFlag(local_context, table_name, table_metadata_path, attach);
tables_metadata_digest = new_digest;
assert(checkDigestValid(local_context));
}
String DatabaseReplicated::readMetadataFile(const String & table_name) const
{
String statement;
ReadBufferFromFile in(getObjectMetadataPath(table_name), METADATA_FILE_BUFFER_SIZE);
readStringUntilEOF(statement, in);
return statement;
}
std::vector<std::pair<ASTPtr, StoragePtr>>
DatabaseReplicated::getTablesForBackup(const FilterByNameFunction & filter, const ContextPtr &) const
{
waitDatabaseStarted(false);
/// Here we read metadata from ZooKeeper. We could do that by simple call of DatabaseAtomic::getTablesForBackup() however
/// reading from ZooKeeper is better because thus we won't be dependent on how fast the replication queue of this database is.
auto zookeeper = getContext()->getZooKeeper();
UInt32 snapshot_version = parse<UInt32>(zookeeper->get(zookeeper_path + "/max_log_ptr"));
auto snapshot = getConsistentMetadataSnapshotImpl(zookeeper, filter, /* max_retries= */ 20, snapshot_version);
std::vector<std::pair<ASTPtr, StoragePtr>> res;
for (const auto & [table_name, metadata] : snapshot)
{
ParserCreateQuery parser;
auto create_table_query = parseQuery(parser, metadata, 0, getContext()->getSettingsRef().max_parser_depth);
auto & create = create_table_query->as<ASTCreateQuery &>();
create.attach = false;
create.setTable(table_name);
create.setDatabase(getDatabaseName());
StoragePtr storage;
if (create.uuid != UUIDHelpers::Nil)
{
storage = DatabaseCatalog::instance().tryGetByUUID(create.uuid).second;
if (storage)
storage->adjustCreateQueryForBackup(create_table_query);
}
/// `storage` is allowed to be null here. In this case it means that this storage exists on other replicas
/// but it has not been created on this replica yet.
res.emplace_back(create_table_query, storage);
}
return res;
}
void DatabaseReplicated::createTableRestoredFromBackup(
const ASTPtr & create_table_query,
ContextMutablePtr local_context,
std::shared_ptr<IRestoreCoordination> restore_coordination,
UInt64 timeout_ms)
{
waitDatabaseStarted(false);
/// Because of the replication multiple nodes can try to restore the same tables again and failed with "Table already exists"
/// because of some table could be restored already on other node and then replicated to this node.
/// To solve this problem we use the restore coordination: the first node calls
/// IRestoreCoordination::acquireCreatingTableInReplicatedDatabase() and then for other nodes this function returns false which means
/// this table is already being created by some other node.
String table_name = create_table_query->as<const ASTCreateQuery &>().getTable();
if (restore_coordination->acquireCreatingTableInReplicatedDatabase(getZooKeeperPath(), table_name))
{
DatabaseAtomic::createTableRestoredFromBackup(create_table_query, local_context, restore_coordination, timeout_ms);
}
/// Wait until the table is actually created no matter if it's created by the current or another node and replicated to the
/// current node afterwards. We have to wait because `RestorerFromBackup` is going to restore data of the table then.
/// TODO: The following code doesn't look very reliable, probably we need to rewrite it somehow.
auto timeout = std::chrono::milliseconds{timeout_ms};
auto start_time = std::chrono::steady_clock::now();
while (!isTableExist(table_name, local_context))
{
waitForReplicaToProcessAllEntries(50);
auto elapsed = std::chrono::steady_clock::now() - start_time;
if (elapsed > timeout)
throw Exception(ErrorCodes::CANNOT_RESTORE_TABLE,
"Couldn't restore table {}.{} on other node or sync it (elapsed {})",
backQuoteIfNeed(getDatabaseName()), backQuoteIfNeed(table_name), to_string(elapsed));
}
}
bool DatabaseReplicated::shouldReplicateQuery(const ContextPtr & query_context, const ASTPtr & query_ptr) const
{
if (query_context->getClientInfo().is_replicated_database_internal)
return false;
/// we never replicate KeeperMap operations for some types of queries because it doesn't make sense
const auto is_keeper_map_table = [&](const ASTPtr & ast)
{
auto table_id = query_context->resolveStorageID(ast, Context::ResolveOrdinary);
StoragePtr table = DatabaseCatalog::instance().getTable(table_id, query_context);
return table->as<StorageKeeperMap>() != nullptr;
};
const auto is_replicated_table = [&](const ASTPtr & ast)
{
auto table_id = query_context->resolveStorageID(ast, Context::ResolveOrdinary);
StoragePtr table = DatabaseCatalog::instance().getTable(table_id, query_context);
return table->supportsReplication();
};
const auto has_many_shards = [&]()
{
/// If there is only 1 shard then there is no need to replicate some queries.
auto current_cluster = tryGetCluster();
return
!current_cluster || /// Couldn't get the cluster, so we don't know how many shards there are.
current_cluster->getShardsInfo().size() > 1;
};
/// Some ALTERs are not replicated on database level
if (const auto * alter = query_ptr->as<const ASTAlterQuery>())
{
if (alter->isAttachAlter() || alter->isFetchAlter() || alter->isDropPartitionAlter() || is_keeper_map_table(query_ptr) || alter->isFreezeAlter())
return false;
if (has_many_shards() || !is_replicated_table(query_ptr))
return true;
try
{
/// Metadata alter should go through database
for (const auto & child : alter->command_list->children)
if (AlterCommand::parse(child->as<ASTAlterCommand>()))
return true;
/// It's ALTER PARTITION or mutation, doesn't involve database
return false;
}
catch (...)
{
tryLogCurrentException(log);
}
return true;
}
/// DROP DATABASE is not replicated
if (const auto * drop = query_ptr->as<const ASTDropQuery>())
{
if (drop->table.get())
return drop->kind != ASTDropQuery::Truncate || !is_keeper_map_table(query_ptr);
return false;
}
if (query_ptr->as<const ASTDeleteQuery>() != nullptr)
{
if (is_keeper_map_table(query_ptr))
return false;
return has_many_shards() || !is_replicated_table(query_ptr);
}
return true;
}
void registerDatabaseReplicated(DatabaseFactory & factory)
{
auto create_fn = [](const DatabaseFactory::Arguments & args)
{
auto * engine_define = args.create_query.storage;
const ASTFunction * engine = engine_define->engine;
if (!engine->arguments || engine->arguments->children.size() != 3)
throw Exception(ErrorCodes::BAD_ARGUMENTS, "Replicated database requires 3 arguments: zookeeper path, shard name and replica name");
auto & arguments = engine->arguments->children;
for (auto & engine_arg : arguments)
engine_arg = evaluateConstantExpressionOrIdentifierAsLiteral(engine_arg, args.context);
String zookeeper_path = safeGetLiteralValue<String>(arguments[0], "Replicated");
String shard_name = safeGetLiteralValue<String>(arguments[1], "Replicated");
String replica_name = safeGetLiteralValue<String>(arguments[2], "Replicated");
zookeeper_path = args.context->getMacros()->expand(zookeeper_path);
shard_name = args.context->getMacros()->expand(shard_name);
replica_name = args.context->getMacros()->expand(replica_name);
DatabaseReplicatedSettings database_replicated_settings{};
if (engine_define->settings)
database_replicated_settings.loadFromQuery(*engine_define);
return std::make_shared<DatabaseReplicated>(
args.database_name,
args.metadata_path,
args.uuid,
zookeeper_path,
shard_name,
replica_name,
std::move(database_replicated_settings), args.context);
};
factory.registerDatabase("Replicated", create_fn);
}
}
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