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ClickHouse® is a real-time analytics DBMS
b0a80af888
Otherwise you can see something like this for the following query:
```sql
WITH
arrayMap(x -> demangle(addressToSymbol(x)), s.trace) AS trace_array,
arrayStringConcat(trace_array, '\n') AS trace_string
SELECT
p.thread_id,
p.query_id,
p.query,
trace_string
FROM
(
SELECT
query_id,
query,
arrayJoin(thread_ids) AS thread_id
FROM system.processes
) AS p
INNER JOIN system.stack_trace AS s ON p.thread_id = s.thread_id
ORDER BY p.query_id ASC
SETTINGS enable_global_with_statement = 0, allow_introspection_functions = 1
FORMAT PrettyCompactNoEscapes
```
Lots of the following:
```sql
INSERT INTO buffer (...) VALUES
__lll_lock_wait
pthread_mutex_lock
std::__1::mutex::lock()
DB::StorageBuffer::reschedule()
DB::BufferBlockOutputStream::write(DB::Block const&)
```
That will wait one of this:
```
INSERT INTO buffer (...) VALUES
...
DB::PushingToViewsBlockOutputStream::write(DB::Block const&)
DB::AddingDefaultBlockOutputStream::write(DB::Block const&)
DB::SquashingBlockOutputStream::finalize()
DB::SquashingBlockOutputStream::writeSuffix()
DB::PushingToViewsBlockOutputStream::writeSuffix()
DB::StorageBuffer::writeBlockToDestination(DB::Block const&, std::__1::shared_ptr<DB::IStorage>)
DB::StorageBuffer::flushBuffer(DB::StorageBuffer::Buffer&, bool, bool, bool)
```
P.S. we cannot simply unlock the buffer during flushing, see comments in
the code
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| base | ||
| benchmark | ||
| cmake | ||
| contrib | ||
| debian | ||
| docker | ||
| docs | ||
| programs | ||
| src | ||
| tests | ||
| utils | ||
| website | ||
| .arcignore | ||
| .clang-format | ||
| .clang-tidy | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| .gitmodules | ||
| .potato.yml | ||
| .vimrc | ||
| AUTHORS | ||
| CHANGELOG.md | ||
| CMakeLists.txt | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| docker-compose.yml | ||
| format_sources | ||
| LICENSE | ||
| PreLoad.cmake | ||
| README.md | ||
| release | ||
| SECURITY.md | ||
| uncrustify.cfg | ||
| ya.make | ||
ClickHouse® is an open-source column-oriented database management system that allows generating analytical data reports in real time.
Useful Links
- Official website has quick high-level overview of ClickHouse on main page.
- Tutorial shows how to set up and query small ClickHouse cluster.
- Documentation provides more in-depth information.
- YouTube channel has a lot of content about ClickHouse in video format.
- Slack and Telegram allow to chat with ClickHouse users in real-time.
- Blog contains various ClickHouse-related articles, as well as announcements and reports about events.
- Code Browser with syntax highlight and navigation.
- Yandex.Messenger channel shares announcements and useful links in Russian.
- Contacts can help to get your questions answered if there are any.
- You can also fill this form to meet Yandex ClickHouse team in person.
Upcoming Events
- SF Bay Area ClickHouse Virtual Office Hours (online) on 20 January 2020.
- Chinese ClickHouse Meetup (online) on 6 February 2020.