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Call Me Maybe: MongoDB Stale Reads

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Re: Call Me Maybe: MongoDB Stale Reads

#51
post #18

Earlier quoted context omitted.

Um, this is the postgres article: https://aphyr.com/posts/282-call-me-maybe-postgres There were no acknowledged writes lost. The only unacked-but-successful writes resulted from a connection while a commit ack was in-flight. That doesn't qualify as a data-consistency error, it means the client has to check if the data is present after reconnecting. But in no cases would the client reconnect to find that there were ac…

I was talking about data consistency more broadly. "However, two writes (215 and 218) succeeded, even though they threw an exception claiming that a failure occurred". This obviously isn't ideal behaviour from the perspective of a developer but isn't necessarily not correct. My broader point was that you need to assume the worst from your database in the application layer. Which I think you missed.

I read your post as FUD regarding Postgres.

That article has various issues, for example, calling Postgres commit protocol as a special case of two phase commit is not really correct. Postgres has 2pc: http://www.postgresql.org/docs/9.2/static/sql-prepare-transa... but that was not tested.

The described behavior is "expected" and "understood". Saying that "you should assume worst from your database" is not something I would ever use for describing DB with ACID semantics.

Re: Call Me Maybe: MongoDB Stale Reads

#52
post #44
post #34

Earlier quoted context omitted.

FoundationDB. Kyle didn't bother running Jepsen against FDB because foundationdb's internal testing was much more rigorous that Jepsen. The foundationdb team ran it themselves and it passed with flying colors: http://blog.foundationdb.com/call-me-maybe-foundationdb-vs-j... Sadly, fdb has been bought by Apple[1], and you can't download it anymore. I sincerely hope foundationdb gets opensourced or something. [1] http:/…

[deleted]

Actually, look at some of the things that @aphyr has tweeted about FoundationDB:

https://twitter.com/aphyr/status/542792308492484608

https://twitter.com/obfuscurity/status/405016890306985984

Re: Call Me Maybe: MongoDB Stale Reads

#54
post #41

Earlier quoted context omitted.

Actually, just use Riak. Those people know distributed bases. https://aphyr.com/posts/285-call-me-maybe-riak Now I hear they support consistency as well.

I think at one point the employees of Basho knew how to write distributed DBs - Riak is the most advanced AP DB from a distributed systems theory perspective. However, in recent months, their CEO, CTO and Chief Architect have left, as well as many of their prominent engineers. Worryingly, the new CTO seems content to make inane comments about "Data Gravity" [0]. [0] - http://www.kdnuggets.com/2015/03/interview-dave-m…

oooh, that is scary.

Re: Call Me Maybe: MongoDB Stale Reads

#55
post #44
post #34

Earlier quoted context omitted.

FoundationDB. Kyle didn't bother running Jepsen against FDB because foundationdb's internal testing was much more rigorous that Jepsen. The foundationdb team ran it themselves and it passed with flying colors: http://blog.foundationdb.com/call-me-maybe-foundationdb-vs-j... Sadly, fdb has been bought by Apple[1], and you can't download it anymore. I sincerely hope foundationdb gets opensourced or something. [1] http:/…

[deleted]

He has said [1] that each test takes literally months to do. I am not surprised that he picks the most popular databases, given the amount of work.

[1] https://github.com/rethinkdb/rethinkdb/issues/1493#issuecomm...

Re: Call Me Maybe: MongoDB Stale Reads

#56
post #41

Earlier quoted context omitted.

Actually, just use Riak. Those people know distributed bases. https://aphyr.com/posts/285-call-me-maybe-riak Now I hear they support consistency as well.

I think at one point the employees of Basho knew how to write distributed DBs - Riak is the most advanced AP DB from a distributed systems theory perspective. However, in recent months, their CEO, CTO and Chief Architect have left, as well as many of their prominent engineers. Worryingly, the new CTO seems content to make inane comments about "Data Gravity" [0]. [0] - http://www.kdnuggets.com/2015/03/interview-dave-m…

Indeed. We're evaluating Riak CS and Swift. In a vacuum, I'd choose Riak CS any day. Knowing all of the drama at Basho, we're in a holding pattern at best and leaning (reluctantly) towards Swift.

Basho needs to sell damn fast or just call it a day and open source the enterprise version.

Re: Call Me Maybe: MongoDB Stale Reads

#57
post #45
post #23

Question: How do I actually run Kyle's tests to see this for myself? (Not that I don't believe him, I just want to play around a bit.) When I run `lein install` and then `lein test`, I get: ╰─▶ ψ lein test Exception in thread "main" java.io.FileNotFoundException: Could not locate jepsen/db__init.class or jepsen/db.clj on classpath: , compiling:(mongodb/core.clj:1:1) at clojure.lang.Compiler.load(Compiler.java:7142) a…

Can't answer your question, but I'm curious how you managed to include an image in your comment. I didn't think embedded HTML was possible?

That's from my command prompt that I wrote -- the arrows are just Unicode characters. You can see it here if you like:

https://github.com/fj/dotfiles/blob/master/home/.config/shel...

Edit: On further reading, I think you seem to be thinking that the paste of my console is an image. It is just text. To make fixed-width text on HN, indent each line by four spaces, like this:

    This text has four spaces at the beginning of its line.

Re: Call Me Maybe: MongoDB Stale Reads

#59

Earlier quoted context omitted.

Postgres: https://aphyr.com/posts/282-call-me-maybe-postgres

Postgres can survive a network partition? I wasn't aware that master-master or sharding+replication was in the box yet?

Did you read the article? It's not about PostgreSQL in a distributed setup:

> Even though the Postgres server is always consistent, the distributed system composed of the server and client together may not be consistent. It’s possible for the client and server to disagree about whether or not a transaction took place.

Re: Call Me Maybe: MongoDB Stale Reads

#60
post #56

Earlier quoted context omitted.

I think at one point the employees of Basho knew how to write distributed DBs - Riak is the most advanced AP DB from a distributed systems theory perspective. However, in recent months, their CEO, CTO and Chief Architect have left, as well as many of their prominent engineers. Worryingly, the new CTO seems content to make inane comments about "Data Gravity" [0]. [0] - http://www.kdnuggets.com/2015/03/interview-dave-m…

Indeed. We're evaluating Riak CS and Swift. In a vacuum, I'd choose Riak CS any day. Knowing all of the drama at Basho, we're in a holding pattern at best and leaning (reluctantly) towards Swift. Basho needs to sell damn fast or just call it a day and open source the enterprise version.

Drama aside, Riak and Swift are not in the same league.
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