Top all-time · #1074
DBMS Musings
Personal blog · dbmsmusings.blogspot.comdatasystems
DBMS Musings is a personal blog at dbmsmusings.blogspot.com about data and systems. Since 2009, 62 different Hacker News readers have linked it 95 times, most often “Problems with CAP, and Yahoo’s little known NoSQL system”. The last post was in 2021, but the archive is still widely read.
Sometimes recommended · 5 of 32 sampled comments recommend it?
Why HN links it
HN readers link Daniel Abadi's blog for its analysis of distributed database consistency, transactions and CAP/PACELC, including comparisons of Spanner, Calvin and NewSQL systems.
- Recommended for · 5 comments
- Excellent comparison of consistency methods; interesting read clarifying CAP; enjoyed by one follower.
Summarised by Claude from a sample of 32 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
Most-linked posts?
- Problems with CAP, and Yahoo’s little known NoSQL system12 people · 13 mentions · first linked 2010-04-26
- NewSQL databases fail to guarantee consistency and I blame Spanner7 people · 8 mentions · first linked 2018-09-21
- The dangers of conditional consistency guarantees4 people · 6 mentions · first linked 2019-07-15
- Problems with CAP, and Yahoo’s Little Known NoSQL System (2010)4 people · 4 mentions · first linked 2018-02-27
- Distinguishing Column-Stores (Cassandra vs. Vertica)4 people · 4 mentions · first linked 2010-03-29
- Why some NoSQL DBs only let you perform transactions on a single data item3 people · 4 mentions · first linked 2015-10-29
- Correctness Anomalies Under Serializable Isolation3 people · 3 mentions · first linked 2019-06-28
- It’s Time to Move on from Two Phase Commit3 people · 3 mentions · first linked 2019-01-25
- Overview of Consistency Levels in Database Systems2 people · 2 mentions · first linked 2019-07-27
- Replication and the latency-consistency tradeoff2 people · 2 mentions · first linked 2011-12-08
What Hacker News says?
I don’t know why the author is surprised that Postgres offers stronger guarantees than serializability in practice. Serializability per se allows anomalies that would be disastrous in practice: http://dbmsmusings.blogspot.com/2019/06/correctness-anomalie... .
Comment linking /2019/06/correctness-anomalies-under.html
on “Jepsen: PostgreSQL 12.3”Submitted NewSQL databases fail to guarantee consistency and I blame Spanner as a story · 510 points
HN discussionHello, author here. That's a good question and something I had a hard time sorting out as I worked on this. I think those fall into a different category confusingly sometimes called column-oriented databases. They're primarily used for analytic-focused tasks and get their name from storing data by column instead of by row (all data in a single column is stored to disk together). I didn't include those as a separate…
Comment linking /2010/03/distinguishing-two-major-types-of_29.html
on “Comparing Database Types”Submitted It’s Time to Move on from Two Phase Commit as a story · 397 points
HN discussionCassandra really isn't a columnstore in the same sense that the word is used for OLAP systems. In the latter, efficient queries can be run across lots of values in a small number of columns across many rows. In Cassandra, queries spanning many rows are not particularly efficient. Sometimes wide-column tables are used for OLAP-type use cases in Cassandra, but that's something of a different approach. More info on tha…
Comment linking /2010/03/distinguishing-two-major-types-of_29.html
on “Making SQL Server run on Linux”Submitted Do we need a third Apache project for columnar data representation? as a story · 168 points
HN discussionI'm very curious about this too. I posted in another thread: "Doesn't that just sweep the latency tradeoff under the rug, or is flash making up the difference? What about the availability tradeoff? (I like the formulation here, consistency vs availability and consistency vs latency, as opposed to CAP which never made sense as a 3-way tradeoff: http://dbmsmusings.blogspot.com/2010/04/problems-with-cap-an... ) http://…
Comment linking /2010/04/problems-with-cap-an...
on “Amazon DynamoDB – a Fast and Scalable NoSQL Database Service from AWS”Submitted Overview of Consistency Levels in Database Systems as a story · 114 points
HN discussionFaunaDB uses Calvin, a transaction protocol developed by Daniel Abadi. Their blog post explains it nicely, after a bit of a slow start: https://fauna.com/blog/consistency-without-clocks-faunadb-tr... But in summary: 1. A 'transaction' is a self-contained blob of code which reads input, does deterministic logic, and writes output (so not like a traditional RDBMS transaction, where the application opens a transaction…
Comment linking /2019/01/its-time-to-move-on-from-two-phase.html
on “FaunaDB 2.5.4”Submitted The difference between isolation levels and consistency levels as a story · 110 points
HN discussion> You cannot give up partition tolerance. It'd be more accurate to say you don't want to give it up all the time. You don't want CAP; you want PACELC. http://dbmsmusings.blogspot.com/2010/04/problems-with-cap-an...
Comment linking /2010/04/problems-with-cap-and-yahoos-little.html
on “Why I love databases”Submitted Scalable ACID as a story · 109 points
HN discussionI was just looking into this, and found this really interesting post about foundationdb and sql. https://www.voltactivedata.com/blog/2015/04/foundationdbs-le... Also this, excellent comparison of distributed database consistency methods, mentions cockroach, but not foundation. http://dbmsmusings.blogspot.com/2018/09/newsql-database-syst... This brings up the question, what method/protocol does foundation use for dis…
Comment linking /2018/09/newsql-database-systems-are-failing-to.html
on “FoundationDB: A distributed unbundled transactional key value store”Submitted Why are Oracle and DB2 still on top of TPC-C? A roadmap to end their dominance. as a story · 96 points
HN discussionYou are correct that they serialize cross-partition transactions. So if your workload has a reasonable percentage of write/update/delete operations it is possible that you will bottleneck on the global coordinator. From this blog https://fauna.com/blog/distributed-acid-transaction-performa... , you can get 3300 transactions/second. Daniel Abadi claims you can get to 500,000 trans/sec - http://dbmsmusings.blogspot.co…
Comment linking /2018/09/newsql-database-systems-are-failing-to.html
on “Consistency Without Clocks: FaunaDB's Distributed Transaction Protocol”Submitted Why some NoSQL DBs only let you perform transactions on a single data item as a story · 89 points
HN discussionIn CAP theorem terms, Redis has picked zero (remember CAP theorem is pick at most two). That might be true, but describing something in the CAP framework is not the only salient thing you can say about a distributed storage system. It is characterizing the failure modes. You also have to think about what happens in the normal case. In the normal case you have a consistency vs. latency tradeoff. People have written a…
Comment linking /2010/04/problems-with-cap-and-yahoos-little.html
on “The Redis criticism thread”Submitted Problems with CAP, and Yahoo’s little known NoSQL system as a story · 76 points
HN discussionPACELC[1] helps distinguish just the kind of CAP sacrifice this makes. [1] http://dbmsmusings.blogspot.com/2010/04/problems-with-cap-an...
Comment linking /2010/04/problems-with-cap-and-yahoos-little.html
on “HyperDex: A Searchable Distributed Key-Value Store”Submitted Do we really need a third Apache project for columnar data? (2017) as a story · 74 points
HN discussionThat depends on what level of book, and what you want to learn from it. On "how real distributed systems are built", there isn't a really good book available in my opinion. I liked The Datacenter as a Computer, but it's scope is fairly narrow and is more focused on global infrastructure issues than software design issues. On the math behind distributed systems, Nancy Lynch's book Distributed Algorithms ( http://www.…
Comment linking /
on “Distributed systems for fun and profit”Submitted Why I no longer trust EMC as a story · 70 points
HN discussionIs there a consensus / standard on the wording of the "consistency level" and "system guarantee"? https://dbmsmusings.blogspot.com/2019/06/correctness-anomali... Classification of serializable systems * (consistency level) READ UNCOMMITTED (ISO) READ COMMITTED (ISO) REPEATABLE READ (ISO) SNAPSHOT ISOLATION SERIALIZABLE (ISO) ONE COPY SERIALIZABLE STRONG SESSION SERIALIZABLE STRONG WRITE SERIALIZABLE STRONG PARTITION…
Comment linking /2019/06/correctness-anomalies-under.html
on “Overview of Consistency Levels in Database Systems”Submitted Slog: Cheating the low-latency vs. strict serializability tradeoff as a story · 62 points
HN discussionA version which was rejected included the following (non-Apache-affiliated [afaik]) references: https://www.xenonstack.com/insights/what-is-apache-arrow/ https://link.springer.com/chapter/10.1007%2F978-1-4842-1311-... https://www.biorxiv.org/content/biorxiv/early/2016/08/23/071... http://delivery.acm.org/10.1145/3110000/3103003/p138-Maas.pd... https://www.theregister.co.uk/2016/02/17/apache_arrow_toplev... https://w…
Comment linking /2017/10/apache-arrow-vs-parquet-and-orc-do-we.html
on “Why there isn’t an Apache Arrow article in Wikipedia”Submitted Distributed consistency at scale: Spanner vs. Calvin (2017) as a story · 62 points
HN discussionThe author basically doesn't believe CAP represents a good model of the database tradeoffs; "Over the past few weeks, in my advanced database system implementation class I teach at Yale, I’ve been covering the CAP theorem, its implications, and various scalable NoSQL systems that would appear to be influenced in their design by the constraints of CAP. Over the course of my coverage of this topic, I am convinced that…
Comment linking /2010/04/problems-with-cap-and-yahoos-little.html
on “Scalable ACID”Submitted Problems with CAP, and Yahoo’s little known NoSQL system as a story · 52 points
HN discussionAbadi has an interesting paper here about why so many NoSQL databases are missing transactions. http://dbmsmusings.blogspot.com/2015/10/why-mongodb-cassandr... The fairness, isolation, and throughput (FIT) tradeoffs seem more interesting to me than CAP.
Comment linking /2015/10/why-mongodb-cassandra-hbase-dynamodb_28.html
on “Spanner vs. Calvin: distributed consistency at scale”Submitted Partitioned consensus and its impact on Spanner’s latency as a story · 50 points
HN discussion
