zX41ZdbW

25 ms·

391.
by zX41ZdbW 3y ago
We use -Wall -Werror -Wextra -Weverything, plus we use clang-tidy with -Werror as well, plus we use ASan, TSan, MSan, UBSan, plus fuzzing (5+ different types of it), plus we update to the latest compiler on every release, so today it is cla
392.
by zX41ZdbW 3y ago
It depends on how the entire cluster gets deleted. If one out of three nodes disappears, but two out of three nodes are shut down properly and written the latest snapshot to S3, it will restore correctly. If two out of three nodes disappear
393.
by zX41ZdbW 3y ago
Thank you! The topic interests to me, and I usually don't hesitate to comment. PS. I'm the developer of ClickHouse and CTO at ClickHouse Inc.
394.
by zX41ZdbW 3y ago
There is no specific reason to start with ZooKeeper, nor with ClickHouse Keeper, if you want to use another distributed consensus system. But: every such system is slightly different in the data model and the set of available primitives. It
395.
by zX41ZdbW 3y ago
That's true - C++ libraries are typically bug-ridden and require exhaustive efforts to clean up. But the latest bugs found by ClickHouse continuous integration system in the related library were fixed about a year ago: https:/&#x
396.
by zX41ZdbW 3y ago
ZooKeeper alternative with: 1. Snapshots and logs take much less amount of space on disk due to better compression. 2. No limit on the default packet and node data size (it is 1 MB in ZooKeeper) 3. No zxid overflow issue (it forces restart
397.
by zX41ZdbW 3y ago
1. Yes, it can be used with other applications as a ZooKeeper replacement, unless some unusual ZooKeper features are used (there is no Kerberos integration in Keeper, and it does not support the TTL of persistent nodes) or the application t
398.
by zX41ZdbW 3y ago
https://github.com/ClickHouse/ClickHouse/issues/45367
399.
by zX41ZdbW 3y ago
The same library that you use for ZooKeeper - kazoo. Note: our stress tests have found a segmentation fault in Python's kazoo library. We only wanted to test Keeper, but found every bug around it :) Let me find a link.
400.
by zX41ZdbW 3y ago
Attempting to present the inability to scale out as a sort of advantage sounds strange to me. The problem with duckdb is that it does not work as a database server. Occasional data analysis may be more or less ok, but you don't need du
401.
by zX41ZdbW 3y ago
SQL could be friendlier for complex queries. We have recently made a talk on the improvements to SQL to simplify complex expressions: https://www.youtube.com/watch?v=zhrOYQpgvkk
402.
by zX41ZdbW 3y ago
It is hard (close to impossible) to write a memory-safe code in C++. In ClickHouse, we approach this with continuous fuzzing. When we tried to integrate duckdb as one of the storage engines into ClickHouse, our CI system immediately found a
403.
by zX41ZdbW 3y ago
I recommend using ClickHouse instead of DuckDB. It has been around since 2016, and it covers and extends the feature set of DuckDB with a huge margin. Worth noting that it never has breaking changes in its table format MergeTree. I'm t
404.
by zX41ZdbW 3y ago
ClickHouse was open-sourced in 2016 and moved to an independent company in 2021, with no ties remaining with Russia or Yandex. Read more: https://clickhouse.com/blog/we-stand-with-ukraine/
405.
by zX41ZdbW 3y ago
In ClickHouse, we name it ClearableHashMap: https://github.com/ClickHouse/ClickHouse/blob/master/src/Com... My colleague Michael Kolupaev, who is an ACM ICPC winner, taught me about this technique l
406.
by zX41ZdbW 3y ago
I write all my presentations in HTML. Advantages: - greater flexibility than with Markdown; - no need to decide between Markdown, ReStructuredText, Wiki markup, BBCode, etc; Disadvantages: - writing closing tags is cumbersome; The source co
407.
by zX41ZdbW 3y ago
This is the same as it's implemented in ClickHouse. In fact, it has two formats: `Protobuf` (with length-delimited messages) and `ProtobufSingle` (no delimiters, but only a single message can be read/written). And it is fairly com
408.
by zX41ZdbW 3y ago
It's hardly comparable with ClickHouse. Even loading a table with 100M rows is not an easy endeavor in Pinot: https://github.com/ClickHouse/ClickBench/blob/main/pinot/ben...
409.
by zX41ZdbW 3y ago
You can analyze this data without Snowflake: https://clickhouse.com/blog/real-world-data-noaa-climate-dat...
410.
by zX41ZdbW 3y ago
It's strange to see no comparison with ClickHouse's MergeTree format in the article.
411.
by zX41ZdbW 3y ago
How can I download the entire dataset from this service?
412.
by zX41ZdbW 3y ago
Only a few database engines have support for ASOF JOIN. Originally implemented in ClickHouse in 2019: https://clickhouse.com/docs/en/sql-reference/statements/sele... but now in a few more database engine
413.
by zX41ZdbW 3y ago
I tried Boiling Data, but the product looks dead or abandoned: https://github.com/ClickHouse/ClickBench/issues/125 It does not work at all.
414.
by zX41ZdbW 3y ago
I also recommend checking the curated collection of example datasets from ClickHouse documentation: https://clickhouse.com/docs/en/getting-started/example-datas... The difference to Kaggle, HuggingFace, and D
415.
by zX41ZdbW 3y ago
Thank you! Should work. PS. When reading about `consteval`, `constinit` you might think, "they (C++ committee) are totally crazy, how they think we can follow"
416.
by zX41ZdbW 3y ago
There is an undefined behavior in the compiler and an undefined behavior in the CPU. For example, bsr/bsf instructions (count leading or trailing bits) have undefined behavior if the argument is zero. What I observed is that the CPU le
417.
by zX41ZdbW 3y ago
It's interesting that the list reads as a recipe for ClickBench. Although I didn't read the article, so it is just a coincidence.
418.
by zX41ZdbW 3y ago
Also I recommend to read the methodology here: https://github.com/ClickHouse/ClickBench/blob/main/README.md Making an open-source, easily reproducible benchmark with clear rules allowed having more than
419.
by zX41ZdbW 3y ago
constexpr is often difficult to get right. For example, we use a wide_integer type for 128 and 256-bit integers: https://github.com/ClickHouse/ClickHouse/blob/master/base/ba... It was developed by a
420.
by zX41ZdbW 3y ago
Too little time to scroll over the list of repositories. It showed me a snippet with Python code for some observability tool, with SELECT count() ... query, so I know that it uses ClickHouse. The right answer was Sentry, but I didn

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