If some string literals are used in DDL, they might have `Character Set Introducers`
https://dev.mysql.com/doc/refman/8.0/en/charset-introducer.html
f.e. _utf8mb4'1' which is not parsable by current ParserStringLiteral.
Since we use utf8 by default, suggesting to automatically convert the string literals to utf8
before executing the query and avoid any charset introducers there.
Conversion from utf8 to utf8 is not needed and skipped.
Also it might convert double quotes to single quotes if any
which might solve issues with COMMENT and empty string literals "" in DEFAULT expressions.
SELECT _latin1"abc"; -- might be also valid for MySQL
... DEFAULT "",
... COMMENT "abc"
Currently no DEFAULT expressions are supported, not parsable at all,
but using this MR it allows to parse the expressions together with double quotes as string literals.
CI founds [1]:
Exception: Sanitizer assert found for instance ==================
WARNING: ThreadSanitizer: data race (pid=348)
Write of size 8 at 0x7b58000044a0 by main thread:
2 DB::DatabaseReplicated::startupTables(ThreadPoolImpl<ThreadFromGlobalPoolImpl<false>>&, DB::LoadingStrictnessLevel) build_docker/./src/Databases/DatabaseReplicated.cpp:526:16 (clickhouse+0x1ec45092)
3 DB::TablesLoader::startupTables() build_docker/./src/Databases/TablesLoader.cpp:87:26 (clickhouse+0x1f9258ab) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
4 DB::loadMetadata(std::__1::shared_ptr<DB::Context>, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&) build_docker/./src/Interpreters/loadMetadata.cpp:234:12 (clickhouse+0x1fff3834) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
5 DB::Server::main() build_docker/./programs/server/Server.cpp:1615:9 (clickhouse+0x163e7f78) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
6 Poco::Util::Application::run() build_docker/./base/poco/Util/src/Application.cpp:315:8 (clickhouse+0x257608fe) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
7 DB::Server::run() build_docker/./programs/server/Server.cpp:391:25 (clickhouse+0x163d7d7c) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
8 Poco::Util::ServerApplication::run(int, char**) build_docker/./base/poco/Util/src/ServerApplication.cpp:131:9 (clickhouse+0x25780114) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
9 mainEntryClickHouseServer(int, char**) build_docker/./programs/server/Server.cpp:196:20 (clickhouse+0x163d4c23) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
10 main build_docker/./programs/main.cpp:487:12 (clickhouse+0xdf8c877) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
Previous read of size 8 at 0x7b58000044a0 by thread T27 (mutexes: write M0, write M1):
1 DB::DatabaseReplicated::canExecuteReplicatedMetadataAlter() const build_docker/./src/Databases/DatabaseReplicated.cpp:1303:12 (clickhouse+0x1ec5c5bd)
2 DB::ReplicatedMergeTreeQueue::shouldExecuteLogEntry() const build_docker/./src/Storages/MergeTree/ReplicatedMergeTreeQueue.cpp:1471:24 (clickhouse+0x2115fb56) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
3 DB::ReplicatedMergeTreeQueue::selectEntryToProcess(DB::MergeTreeDataMergerMutator&, DB::MergeTreeData&) build_docker/./src/Storages/MergeTree/ReplicatedMergeTreeQueue.cpp:1676:13 (clickhouse+0x21163c58) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
4 DB::StorageReplicatedMergeTree::selectQueueEntry() build_docker/./src/Storages/StorageReplicatedMergeTree.cpp:3240:26 (clickhouse+0x20823db2) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
5 DB::StorageReplicatedMergeTree::scheduleDataProcessingJob(DB::BackgroundJobsAssignee&) build_docker/./src/Storages/StorageReplicatedMergeTree.cpp:3304:65 (clickhouse+0x208240fc) (BuildId: 7d4ce55d33d4c3e3df9fd39b304e67e53eb61a63)
[1]: https://s3.amazonaws.com/clickhouse-test-reports/52395/0b258dda4ee618a4d002e2b5246d68bbd2c77c7e/integration_tests__tsan__[5_6].html
Add ddl_worker_initialized flag to avoid this race.
Note, that it should be enough to check this flag only in
canExecuteReplicatedMetadataAlter() since only it can be run in parallel
with ctor before it had been finished.
v0: initialize ddl before startupTables()
v2: ddl_worker_initialized
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
Co-authored-by: Alexander Tokmakov <tavplubix@clickhouse.com>
