Slashdot Mirror

← Back to Stories (view on slashdot.org)

Cassandra Rewritten In C++, Ten Times Faster

Posted by samzenpus on from the greased-lightning dept.

urdak writes: At Cassandra Summit opening today, Avi Kivity and Dor Laor (who had previously written KVM and OSv) announced ScyllaDB — an open-source C++ rewrite of Cassandra, the popular NoSQL database. ScyllaDB claims to achieve a whopping 10 times more throughput per node than the original Java code, with sub-millisecond 99%ile latency. They even measured 1 million transactions per second on a single node. The performance of the new code is attributed to writing it in Seastar — a C++ framework for writing complex asynchronous applications with optimal performance on modern hardware.

5 of 341 comments (clear)

  1. %ile? Are We Texting? by Anonymous Coward · · Score: 5, Insightful

    Seriously. WTF?

  2. Garbage collected virtual machines! by Anonymous Coward · · Score: 5, Insightful

    Almost as fast as native! Maybe even faster for some tasks!

    sure

    1. Re:Garbage collected virtual machines! by Luke+Wilson · · Score: 5, Insightful

      Most of what they've done seems to be rearchitecting, not getting a simple speed boost from using an unmanaged language. They're bypassing the OS to get more locality and cache retention. Those problems would not be addressed by merely rewriting in C++.

      For one, they've replaced the OS network stack with an in-process one, where each thread gets its own NIC queue so they can have "zero-copy, zero-lock, and zero-context-switch[es]"

      They're also keeping more data in memory and eschewing relying on the the OS file cache. It seems like they're taking every opportunity to use the in memory representation to avoid using sstables. They try harder than Cassandra to update instead of invalidate that cache on writes.

  3. Re: Because it was written in Seastar or C++ by Anonymous Coward · · Score: 5, Insightful

    Cassandra is nothing to sneeze out since it outperforms other db-engines (which are written in C, like MySQL).

    Cassandra and MySQL are very different types of databases designed to handle different tasks. It's like saying a hammer is better than the saw without mentioning what job needs to be done with it.

  4. Re:It's a miracle! C++ makes disks spin 10x faster by garethjrowlands · · Score: 5, Insightful

    Databases used to be disk bound, sure. But these days we have huge RAM caches and SSDs - no spinning disks. It's very common for the vast majority of requests to be served entirely from cache. Read the guys' site - it looks like they know what they're doing.

    Imagine if Redis was ten times slower or ten times faster. It would matter.