zX41ZdbW

18 ms·

331.
by zX41ZdbW 3y ago
https://clickhouse.com/docs/en/about-us/adopters
332.
by zX41ZdbW 3y ago
Superset is powerful, but I wonder why they don't fix "papercuts", e.g., misaligned pixels on a spinner, or inability to copy a value from a table's cell, or non-monospace font for numbers in a table, etc. There are hund
333.
by zX41ZdbW 3y ago
ClickHouse supports it for actual INSERT queries. So instead of INSERT ... VALUES, you write INSERT ... FORMAT JSONEachRow and stream your data. https://clickhouse.com/docs/en/sql-reference/statements/ins
334.
by zX41ZdbW 3y ago
ClickHouse automatically detects variations of the JSONEachRow format: - allowing optionally enclosing the data into an array; - allowing comma as an optional separator between objects; - allowing JSON objects without a newline separator; -
335.
by zX41ZdbW 3y ago
We have the same check for silent data corruption in ClickHouse. After it detects a checksum mismatch, it also tries to check if it is caused by a single bit flip. If it is, we can provide a more precise diagnostic for a user about possible
336.
by zX41ZdbW 3y ago
It reminds me of a project I've built recently: https://reversedns.space/ Although it is not guaranteed to contain every RGB color, it is very likely.
337.
by zX41ZdbW 3y ago
I found their claims exaggerated: https://github.com/siglens/siglens/issues/created_by/alexey-...
338.
by zX41ZdbW 3y ago
The LowCardinality data type does not require the whole set of values to have a low cardinality. It benefits when the values have locally low cardinality. For example, if the number of unique values in `repo_name` is a hundred million, but
339.
by zX41ZdbW 3y ago
This is an ad-hoc query. It does a full scan, processing slightly less than a billion rows per second on a single machine, and finishes in a reasonable time with over 7 billion events on GitHub from 2015. While it does not make sense to opt
340.
by zX41ZdbW 3y ago
It is still under the limit today with 362,107,148 repositories and 818,516,506 unique issues and pull requests: https://play.clickhouse.com/play?user=play#U0VMRUNUIHVuaXEoc...
341.
by zX41ZdbW 3y ago
Also fun reading: "Limitations on time zones support" at https://clickhouse.com/docs/en/sql-reference/data-types/date... > A similar issue exists for Casey Antarctic station in the year 2010
342.
by zX41ZdbW 3y ago
There are many Postgres forks for OLAP workloads, such as: - Greenplum; - Citus with cstore_fdw; - IMCS (Konstantin Knizhnik); - Hydra; - AlloyDB; For example, Greenplum is one of the earliest, fairly mature, but abandoned.
343.
by zX41ZdbW 3y ago
In the footnotes, there is an HTML injection after: "Consider the following code that calculates cosine using numerical methods:" PS. Recently, we've tried to turn on and tested the impact of `-fno-omit-frame-pointer` in Clic
344.
by zX41ZdbW 3y ago
Thompson Sampling, a.k.a. Bayesian Bandits, is a powerful method for runtime performance optimization. We use it in ClickHouse to optimize compression and to choose between different instruction sets: https://clickhouse.com/
345.
by zX41ZdbW 3y ago
I also recommend checking this: https://codisec.com/binary-data-visualization/ - visualization of binaries by mapping n-grams into n-dimensional space.
346.
by zX41ZdbW 3y ago
I recently did a very similar thing, but for visualizing DNS records on IPv4: https://reversedns.space/
347.
by zX41ZdbW 3y ago
ClickHouse has support for this as an "ANY" JOIN modifier: https://clickhouse.com/docs/en/sql-reference/statements/sele...
348.
by zX41ZdbW 3y ago
The power off button on the monitor does not work. If I type " http://yahoo.com/ " in the address bar, it does not work as expected. Clicking on the Netscape Navigator logo works, but if I type the same address, &qu
349.
by zX41ZdbW 3y ago
But I continue to find garbage in some of our CI scripts. Here is an example: https://github.com/ClickHouse/ClickHouse/pull/58794/files The right way is to: - always pin versions of all packages; - this
350.
by zX41ZdbW 3y ago
Recently, there were similar attempts (two) of supply chain attacks on the ClickHouse repository, but: - it didn't do anything because CI does not run without approval; - the user's account magically disappeared from GitHub with a
351.
by zX41ZdbW 3y ago
When I press "up" on the website opened in Firefox, it scrolls up very slowly and with a noticeable jitter. It is nice to see the display model easily rotating in 3D, but the on/off button is not clickable. The logos at the t
352.
by zX41ZdbW 3y ago
You can recreate this dataset by your own, it is fairly easy: https://github.com/ClickHouse/ClickHouse/issues/29693
353.
by zX41ZdbW 3y ago
I doubt it is novel. For example, ClickHouse has the WITH FILL modifier for ORDER BY: https://clickhouse.com/docs/en/sql-reference/statements/sele...
354.
by zX41ZdbW 3y ago
You can allow users to write direct SQL queries or use SQL as API if the database server does all of the following: 1. Access control. Table and column-level access control. Row-level restrictions by expressions. Out-of-band table filters t
355.
by zX41ZdbW 3y ago
I recommend checking the dataset of "YouTube dislikes": https://clickhouse.com/docs/en/getting-started/example-datas... (it is named this way because it was an archival effort to collect the informa
356.
by zX41ZdbW 3y ago
We've made experiments, but the usage of this tier is still being considered. One of the proposals is: - use it to simplify the cache instead of local SSDs; - it has to be in every AZ where there are replicas; the caches will work inde
357.
by zX41ZdbW 3y ago
No, updates are also synchronous. A table in ClickHouse is represented by a set of immutable data parts. SELECT query acquires a snapshot of currently active data parts and uses it for reading. INSERT query creates a new data part (or many)
358.
by zX41ZdbW 3y ago
A small correction about ClickHouse Cloud: 1. It uses a cache on local SSDs ("instance store" in AWS terms) + page cache in memory. 2. This is a write-through cache. The data is written into cache and S3. 3. Writes to S3 are synch
359.
by zX41ZdbW 3y ago
ClickHouse has always-on profiling without frame pointers. But the implementation is very hard - it required patching of LLVM's libunwind to make it 100% async-signal safe. Using frame pointers should be easier and faster.
360.
by zX41ZdbW 3y ago
It is the case when you use a default malloc, default memcpy, or default string functions from libc. In ClickHouse, we use jemalloc as a memory allocator and custom memcpy: https://github.com/ClickHouse/ClickHouse/

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