Comment by ysleepy | Hacker News Reader

Comment by ysleepy | Hacker News Reader

So I assume this means cockroachDB currently (probably) meets its promised consistency levels. How does it compare to the usual default settings of PostgreSQL for example? - I think you get SERIALIZABLE, so the behaviour should be very reasonable.

I understand the txn/s numbers are in a pathological scenario, but will these transactions block the whole db from moving faster or have unrelated transactions still normal throughput?

I'm just glad we get linearizable single keys, I had to switch to HBase because it was the only choice at the time. Cassandra did not even give me read-your-own-writes. HBase also had issues while testing on the same host, delete+write lead to deletes being reordered after the writes because they had the same timestamp.

I'm a bit disappointed from HN in this post, everyone only talks about the name. But 90% probably did not even read the article. Aaanyway, heres my 2cents: https://cr.yp.to/cdb.html is CDB for me :P - so better choose another acronym!

> How does it compare to the usual default settings of PostgreSQL for example? - I think you get SERIALIZABLE, so the behaviour should be very reasonable.

Not clear if you're referring to PostgreSQL or CockroachDB, but for the record, the PostgreSQL default transaction isolation level is READ COMMITTED, not SERIALIZABLE.

https://www.postgresql.org/docs/current/static/sql-set-trans...

(Cockroach Labs CTO) CockroachDB provides two transaction isolation levels: SERIALIZABLE, which is our default and the highest of the four standard SQL isolation levels, and SNAPSHOT, which is a slightly weaker mode similar to (but not quite the same as) REPEATABLE READ. Unlike most databases which default to lower isolation modes like REPEATABLE READ or READ COMMITTED, we default to our highest setting because we don't think you should have to think about which anomalies are allowed by different modes, and we don't want to trade consistency for performance unless the application opts in.

All transaction interactions are localized to particular keys, so other transactions can proceed normally while there is contention in an unrelated part of the database.

(as for the acronym, we prefer CRDB instead of CDB)

I don't believe CockroachDB provides SERIALIZABLE consistency for the entire keyspace, rather for subsets of the keyspace that reside in the same Raft cluster.

In practice this means no cross key serializability without including a serialization token in transactions.

I may be mistaken however but that is my understanding from reading CockroachDB docs and Aphyrs post.

Cockroach Labs employee here. We provide serializable consistency for the whole keyspace. It's just that it's easier when you stay in one Raft ensemble as less can go wrong.

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