Plurk Open Source - LightCloud - Distributed and persistent key value database
http://opensource.plurk.com/LightCloud/

aid, here is what it takes to do 10.000 gets and sets:

Redis is a key-value database. It is similar to memcached but the dataset is not volatile, and values can be strings, exactly like in memcached, but also lists and sets with atomic operations to push/pop elements.

“Redis is a key-value database. It is similar to memcached but the dataset is not volatile, and values can be strings, exactly like in memcached, but also lists and sets with atomic operations to push/pop elements. “In order to be very fast but at the same time persistent the whole dataset is taken in memory and from time to time and/or when a number of changes to the dataset are performed it is written asynchronously on disk. You may lost the last few queries that is acceptable in many applications but it is as fast as an in memory DB (beta 6 of Redis includes initial support for master-slave replication in order to solve this problem by redundancy).”

A nice fast K/V data store, with some nice list/set features.

The first one is to use an in-memory data store, and communicate using the memcached protocol. This is, of course, *exactly* comparable to Memcached — behaviorally indistinguishable! — and it does worse. The second option is to do that, except switch to an on-disk data store. It’s pretty ridiculous that that’s still the same speed — communication overhead is completely dominating the time. Fortunately, Tyrant comes with a binary protocol. Using that substantially improves performance past Memcached levels, though less than a direct in-process database. Yes, communication across processes incurs overhead. No news here, I guess.

"Tokyo Tyrant is a server implemented on top of Cabinet that implements a similar key/value API except over sockets. It’s incredibly flexible; it was very easy to run it in several different configurations. The first one is to use an in-memory data store, and communicate using the memcached protocol. This is, of course, *exactly* comparable to Memcached — behaviorally indistinguishable! — and it does worse. The second option is to do that, except switch to an on-disk data store. It’s pretty ridiculous that that’s still the same speed — communication overhead is completely dominating the time. Fortunately, Tyrant comes with a binary protocol. Using that substantially improves performance past Memcached levels, though less than a direct in-process database. Yes, communication across processes incurs overhead. No news here, I guess."

"Most of today’s up and coming key-value stores are more than just simple key-value stores. You saw this when we looked at Tokyo Cabinet which, in addition to simple key-value capabilities, adds more sophisticated abilities, such as database-like tables. In this post we’ll look at Cassandra — a modern key-value store that continues this trend. Cassandra was originally developed by Facebook and released to open source last year. The Facebook team describes Cassandra as (Google) BigTable running on top of an Amazon Dynamo-like infrastructure."

Most of today's and up and coming key-value stores are more than just simple key-value stores. Cassandra is a modern key-value store that continues this trend.

Really interesting article about mongoDB and about the installation procedure

"MongoDB can be thought of as the goodness that erupts when a traditional key-value store collides with a relational database management system, mixing their essences into something that’s not quite either, but rather something novel and fascinating. -- MongoDB support is available in many languages, making it a good choice for a system that has to work in a polyglot environment; all of the major languages have support."

キーバリューストアの解説 「CAP定理」では、分散システムで以下の3つを同時に保証することは不可能であることが示されています。 * データの整合性（Consistency） * データの可用性（Availability） * データの分散化（Partition-tolerance）

>RDBとは別の、クラウド時代のデータベースとして注目を浴びている「分散Key-Valueストア」。その本命ともいえる、Googleの数々のサービスの基盤技術「Bigtable」について徹底解説 どうかなあ…

Bigtable, SimpleDB, Tokyo Tyrant

a database implementing a dictionary, where every key is associated with a value. every single value has a type. The following types are supported: * Strings * Lists * Sets * Sorted Set (since version 1.1)

maybe the guy is not suitable to address such compare?

Persistent in-memory key value database compared to memcached

tructures and algorithms. Indeed both algorithms and data structures in Redis are properly choosed in order to obtain the best performance.

記者にとって驚きだったのは、現在日本で開発されているキー・バリュー型データストアがこの3つに留まらないことだった。しかも開発者は総じて若い。勉強会に参加する80人近くの技術者も、ほぼ同年代だった。

キー・バリュー型データストア（またはキー・バリュー型データベース）は、大量のユーザーとデータを抱え、データベースのパフォーマンス問題とコスト高に頭を悩ませるWeb企業が注目する技術である。

For those familiar with memcached, membase provides on-the-wire protocol compatibility, but adds disk persistence; hierarchical storage management; data replication; live cluster reconfiguration and rebalancing; and secure multi-tenancy with data partitioning. Like memcached, membase is simple, fast and elastic.

Persistent Key/Value Storage

Membase is an open-source (Apache 2.0 license) distributed, key-value database management system optimized for storing data behind interactive web applications. These applications must service many concurrent users; creating, storing, retrieving, aggregating, manipulating and presenting data in real-time. Supporting these requirements, membase processes data operations with quasi-deterministic low latency and high sustained throughput.

from oreilly news link

Membase is an open-source (Apache 2.0 license) distributed, key-value database management system optimized for storing data behind interactive web applications. These applications must service many concurrent users; creating, storing, retrieving, aggregating, manipulating and presenting data in real-time. Supporting these requirements, membase processes data operations with quasi-deterministic low latency and high sustained throughput. It scales linearly from a single-server deployment to a cluster of thousands of machines. And because membase does not require creation of a schema before storing data, it is a flexible, cost-effective place to Store Lots of Stuff.

Membase is an open-source (Apache 2.0 license) distributed, key-value database management system optimized for storing data behind interactive web applications. These applications must service many concurrent users; creating, storing, retrieving, aggregating, manipulating and presenting data in real-time. Supporting these requirements, membase processes data operations with quasi-deterministic low latency and high sustained throughput. It scales linearly from a single-server deployment to a cluster of thousands of machines. And because membase does not require creation of a schema before storing data, it is a flexible, cost-effective place to Store Lots of Stuff. The original membase source code was released as Open Source by NorthScale, Zynga and NHN to membase.org in June 2010.