MongoDB shares jump more than 30% in $192M IPO

Re:MongoDB shares jump more than 30% in $192M IPO by dsp1234 on Thursday October 19, 2017 @01:41PM (#15509904)

They even got through Jepsen just fine after wiredtiger.

With non-default settings[0].

The Jepsen tests passed with the "linearizable" read concern. The default read concern is "local", which "Provides no guarantee that the data has been written to a majority of the replica set members (i.e. may be rolled back)."[1] This is like having "READ UNCOMMITTED" be the default read level in a traditional database system.

The Jepsen tests passed with the "majority" write concern. The default write concern is "1", which means only the "primary" in a replica set needs to acknowledge the write[2]. This does not guarantee safety in the face of network partitions.

It's still not safe out of the box.

[0] - https://jepsen.io/analyses/mongodb-3-4-0-rc3

"With the v1 protocol, majority writes, and linearizable reads, MongoDB 3.4.1 (and the current development release, 3.5.1) pass all MongoDB Jepsen tests:"

[1] - https://docs.mongodb.com/manual/reference/read-concern/

[2] - https://docs.mongodb.com/manual/reference/write-concern/

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Re:MongoDB shares jump more than 30% in $192M IPO by stingraycharles on Thursday October 19, 2017 @02:23PM (#15510308)

These kind of default settings make sense, though. If you really care about lineair writes, you know how to configure it.

Same goes for example for PostgreSQL [1], that uses Read Committed rather than Serializable transaction isolation by default because for the majority of the people, this is fine, and the performance tradeoffs are worth it.

[1] https://www.postgresql.org/docs/9.5/static/transaction-iso.h...

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Re:MongoDB shares jump more than 30% in $192M IPO by bpicolo on Thursday October 19, 2017 @03:07PM (#15510692)

Yeah, and you can turn off fsync in postgres if you want a blazing fast db that loses your data. :D

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Re:MongoDB shares jump more than 30% in $192M IPO by threeseed on Thursday October 19, 2017 @04:03PM (#15511103)

This meme isn't even funny anymore.

It was a bug that was fixed many, many years ago and was only true if you didn't use any client libraries.

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Re:MongoDB shares jump more than 30% in $192M IPO by threeseed on Thursday October 19, 2017 @04:06PM (#15511123)

Not sure if you know much about databases but those are standard defaults.

Cassandra as well doesn't require a full quorum to acknowledge writes. It just relies on the closest node. Likewise for Oracle.

http://docs.datastax.com/en/archived/cassandra/2.0/cassandra...

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