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The write last, read first rule

tigerbeetle.com

11–20 of 32 posts

Re: The write last, read first rule

#12
I found the article interesting, but I don't think I understand what is meant by 'Write Last, Read first' rule - even after reading it a few times. It seems to be too ambiguous a statement to be helpful.

Under the section 'Order of Operations':

> "Since the system of reference doesn’t determine existence, we can safely write to it first without committing anything. [...]"

Then the next paragraph

> "This principle—Write Last, Read First—ensures that we maintain application level consistency."

What I think it means is, 'writing-last to the system-of-record' and 'a read-first from the system of record' yields authoritative results, but I don't get that just from the title. Is my understanding correct?

Re: The write last, read first rule

#13

I found the article interesting, but I don't think I understand what is meant by 'Write Last, Read first' rule - even after reading it a few times. It seems to be too ambiguous a statement to be helpful. Under the section 'Order of Operations': > "Since the system of reference doesn’t determine existence, we can safely write to it first without committing anything. [...]" Then the next paragraph > "This principle—Wri…

I think they just reinvented 2-phase commit? I'm not sure either tbh.

Re: The write last, read first rule

#14

Joran from TigerBeetle! Happy to answer any questions. And thanks to Dominik Tornow of Resonate for writing this up as a guest post! It was a little rule we had coined, to help people remember how to preserve consistency across different DBMS's, and I think Dominik gave (beautiful) voice to it.

IMO the example about checkpointing is not that demonstrative because creating entities is easy to make idempotent. What about transactions? Do they need idempotency and if so, how does it work?

Re: The write last, read first rule

#16
post #2

[flagged]

But it's not an AI generated image, it has the artist's signature in the bottom right corner. Tigerbeetle has a lot of custom artwork designed for their stuff that's high quality. I don't even see why you would think it was AI generated even without the artist signature, it's using the Tigerbeetle mascot and it looks drawn for the particular theme the blog is talking about.

[deleted]

Re: The write last, read first rule

#17

I found the article interesting, but I don't think I understand what is meant by 'Write Last, Read first' rule - even after reading it a few times. It seems to be too ambiguous a statement to be helpful. Under the section 'Order of Operations': > "Since the system of reference doesn’t determine existence, we can safely write to it first without committing anything. [...]" Then the next paragraph > "This principle—Wri…

Yes, write last to the system of record, read first from the system of record. Or in other words, commit to the system of record, and then read from the system of record to see what's committed.

(This is similar also to how chain replication preserves consistency.)

Re: The write last, read first rule

#18

I found the article interesting, but I don't think I understand what is meant by 'Write Last, Read first' rule - even after reading it a few times. It seems to be too ambiguous a statement to be helpful. Under the section 'Order of Operations': > "Since the system of reference doesn’t determine existence, we can safely write to it first without committing anything. [...]" Then the next paragraph > "This principle—Wri…

Not sure why this was downvoted, the comment is completely right.

Re: The write last, read first rule

#19

Joran from TigerBeetle! Happy to answer any questions. And thanks to Dominik Tornow of Resonate for writing this up as a guest post! It was a little rule we had coined, to help people remember how to preserve consistency across different DBMS's, and I think Dominik gave (beautiful) voice to it.

I concur with https://news.ycombinator.com/item?id=45886850, the article doesn’t actually spell out what the “Write Last, Read First” rule is supposed to say. The name of the rule also isn’t great, because it leaves open what to write to/read from, and doesn’t even suggest that there might be several systems to write to/read from, which however is essential to the rule.

Re: The write last, read first rule

#20

I found the article interesting, but I don't think I understand what is meant by 'Write Last, Read first' rule - even after reading it a few times. It seems to be too ambiguous a statement to be helpful. Under the section 'Order of Operations': > "Since the system of reference doesn’t determine existence, we can safely write to it first without committing anything. [...]" Then the next paragraph > "This principle—Wri…

I think they just reinvented 2-phase commit? I'm not sure either tbh.

No, in two-phase commit all target systems perform two phases (staging the commit, which may fail, and then actually committing it in a failsafe way), which isn’t the case here.
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