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Khepri is a tree-like replicated on-disk database library for Erlang and Elixir

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Re: Khepri is a tree-like replicated on-disk database library for Erlang and Elixir

#11

Post by dagss »

innocentoldguy wrote: post #8
detaro wrote: post #7

Earlier quoted context omitted.

"Started"? That both forms are used, somewhat depending on field, is not really a new thing.

It's relatively new to me. When I was in college, books like "The Future of Data Analysis (JW Tukey, 1962) used "data is." I believe all of my CS textbooks treated the word "data" as a singular collection back then. I've only noticed the ubiquitousness of "data are" in engineering books since the turn of the century. It could be a false memory though, which is why I'm asking.

Data is the latin plural of the latin word datum...which for some reason is out of use and we now call that "data point".

Anyway, "data" as plural is a couple of thousands years old.

Re: Khepri is a tree-like replicated on-disk database library for Erlang and Elixir

#12

Post by ramchip »

samsquire wrote: post #10

This is interesting in that it uses Raft. I had a go at implementing a toy Raft implementation and I think testing my particular implementation properly would be pretty hard to do without TLA or automated proofing algorithms. You could also use Jepsen. I maintained a clustered RabbitMQ cluster and used Chef to coordinate upgrades. Uprading Erlang AND RabbitMQ at the same time wasn't very enjoyable since it had the po…

Quorum queues already solve this problem today. They pass a "harsher" fork of Jepsen, according to the RMQ team.

Khepri is a newer project that reuses the Raft library developed for quorum queues to store metadata, as a replacement for Mnesia, Erlang's built-in distributed DB. I think that means things like vhosts, users, permissions, etc.

Re: Khepri is a tree-like replicated on-disk database library for Erlang and Elixir

#13

Post by zelphirkalt »

innocentoldguy wrote: post #6

This is only tangentially related to Khepri, but I'm curious why the STEM community started treating the word "data" like a plural noun, e.g., "Data ARE stored in a tree structure"? I know in Latin, "data" is plural and "datum" is singular, but we aren't speaking Latin, and even if we were, we're not doing so consistently. For example, we don't say, "The meeting's agenda ARE up to date," even though "agenda" is plura…

> To me, saying "Data are..." is pretentious, like when people use the word "an" before words that start with a consonant.

Afaik that is only done for words, which sound like they start with a vowels and I think it is done for easier pronunciation. Why is that pretentious?

Re: Khepri is a tree-like replicated on-disk database library for Erlang and Elixir

#14

Post by innocentoldguy »

dagss wrote: post #11
innocentoldguy wrote: post #8

Earlier quoted context omitted.

It's relatively new to me. When I was in college, books like "The Future of Data Analysis (JW Tukey, 1962) used "data is." I believe all of my CS textbooks treated the word "data" as a singular collection back then. I've only noticed the ubiquitousness of "data are" in engineering books since the turn of the century. It could be a false memory though, which is why I'm asking.

Data is the latin plural of the latin word datum...which for some reason is out of use and we now call that "data point". Anyway, "data" as plural is a couple of thousands years old.

Yes. I mentioned this (and a comparison to the way we use agenda vs. agendum) in my original post.

Re: Khepri is a tree-like replicated on-disk database library for Erlang and Elixir

#15

Post by innocentoldguy »

zelphirkalt wrote: post #13
innocentoldguy wrote: post #6

This is only tangentially related to Khepri, but I'm curious why the STEM community started treating the word "data" like a plural noun, e.g., "Data ARE stored in a tree structure"? I know in Latin, "data" is plural and "datum" is singular, but we aren't speaking Latin, and even if we were, we're not doing so consistently. For example, we don't say, "The meeting's agenda ARE up to date," even though "agenda" is plura…

> To me, saying "Data are..." is pretentious, like when people use the word "an" before words that start with a consonant. Afaik that is only done for words, which sound like they start with a vowels and I think it is done for easier pronunciation. Why is that pretentious?

That's not what I mean. The grammar rule isn't "a" before vowels and "an" before consonants, it is "a" before words that start with vowel sounds and "an" before words that begin with consonant sounds, regardless of what letter the word actually begins with (e.g., "an hour" is correct, even though "hour" starts with an "H"). This is normal.

What I'm talking about is when people reverse this rule to make themselves sound smarter. For example, I have worked with a few people during my career who would say things like, "I will need an pen and an paper to take notes." When I asked why they did that, they'd parrot back the grammar rule for who vs. whom, which is entirely wrong. This is what I mean by pretentious.

Re: Khepri is a tree-like replicated on-disk database library for Erlang and Elixir

#16

Post by innocentoldguy »

detaro wrote: post #9
innocentoldguy wrote: post #8

Earlier quoted context omitted.

It's relatively new to me. When I was in college, books like "The Future of Data Analysis (JW Tukey, 1962) used "data is." I believe all of my CS textbooks treated the word "data" as a singular collection back then. I've only noticed the ubiquitousness of "data are" in engineering books since the turn of the century. It could be a false memory though, which is why I'm asking.

My impression from styleguides etc is that the singular form is the newer one, and in some cases only somewhat begrudgingly accepted. E.g. recommendations that it is acceptable to use singular when writing for a "general audience", not in "formal or scientific writing", others referring to plural as "still in common use" (but singular taking over). But maybe there's been indeed a return to it in this specific field?…

Thanks for the explanation. +1.

Re: Khepri is a tree-like replicated on-disk database library for Erlang and Elixir

#17

Post by dumbbell_fr »

innocentoldguy wrote: post #6

This is only tangentially related to Khepri, but I'm curious why the STEM community started treating the word "data" like a plural noun, e.g., "Data ARE stored in a tree structure"? I know in Latin, "data" is plural and "datum" is singular, but we aren't speaking Latin, and even if we were, we're not doing so consistently. For example, we don't say, "The meeting's agenda ARE up to date," even though "agenda" is plura…

When I wrote that documentation (and comments in the code), I searched if "data" was singular or plural in English (which is not my mother tongue), because I had no idea what it was. According to the sources I found at that time, there were no clear definition, but it looked like to me it was mostly plural.

Re: Khepri is a tree-like replicated on-disk database library for Erlang and Elixir

#18

Post by dumbbell_fr »

Dowwie wrote: post #5

My understanding after spending a few minutes reading through the project web page and stack overflow listings about RabbitMQ clustering problems is as follows. Khepri is a project intended to replace Mnesia for replicated, clustered distributed systems written in Erlang/Elixir such as RabbitMQ. The primary reason this project started was to address shortcomings of Mnesia with regards to "network partitions", where c…

As one of the authors of Khepri, I should probably clarify what we mean by "alpha" quality in the README/documentation.

The data is handled by our Raft library underneath which is production ready, so for a given version of Khepri, the data is safe.

However, the public API and internals of Khepri are unstable. Therefore, as a user of Khepri, you may have to adapt your code when upgrading Khepri to a later version. If the internals change too, you may need to work on some migration tool to export the existing data and import it in a new instance. This is not something Khepri will do for you with an upgrade before it reaches 1.0.0.

And you are right that RabbitMQ releases don't use Khepri at all for now and rely entirely on Mnesia. Future releases will introduce Khepri gradually, for vhosts and users first, and more types of records with each minor release.

Re: Khepri is a tree-like replicated on-disk database library for Erlang and Elixir

#19

Post by innocentoldguy »

dumbbell_fr wrote: post #17
innocentoldguy wrote: post #6

This is only tangentially related to Khepri, but I'm curious why the STEM community started treating the word "data" like a plural noun, e.g., "Data ARE stored in a tree structure"? I know in Latin, "data" is plural and "datum" is singular, but we aren't speaking Latin, and even if we were, we're not doing so consistently. For example, we don't say, "The meeting's agenda ARE up to date," even though "agenda" is plura…

When I wrote that documentation (and comments in the code), I searched if "data" was singular or plural in English (which is not my mother tongue), because I had no idea what it was. According to the sources I found at that time, there were no clear definition, but it looked like to me it was mostly plural.

I meant no disrespect to you and apologize if it came across that way. It's a weirdness (in my opinion) of English and how we adapt Latin words into our grammar in inconsistent ways.
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