SenseiDB

SenseiDB is a distributed database that supports the backend of LinkedIn homepage and LinkedIn Signal. The data is protected by replication and eventual consistency is guaranteed. SenseiDB is also a search engine for look-ups on structured metadata and unstructured contents.

History

SenseiDB was initially developed and employed by LinkedIn team in 2009. Engineers from both LinkedIn and Xiaomi were working on the project. It then became an open-source project that was contributed by many individuals. After three releases, SenseiDB has no longer updated or used since year 2013.

Checkpoints

Not Supported

Concurrency Control

Not Supported

SenseiDB does not support concurrent operations . Only a single thread can run at a time. Besides, transactions are not supported as well.

Data Model

Relational

SenseiDB is a relation database that are organized with tables. The users are able to index and retrieve the data with *Browsing Query Language* (BQL).

Indexes

Inverted Index (Full Text)

SenseiDB applies an indexing manager called [Zoie](http://javasoze.github.io/zoie/), which is an independent searching and indexing engine built on [Apache Lucene](https://pdfs.semanticscholar.org/2795/d9d165607b5ad6d8b9718373b82e55f41606.pdf) that uses inverted index to efficiently retrieve data. The biggest feature of Zoie is the support for real-time searches and updates.

Logging

Not Supported

Query Compilation

Not Supported

Query Execution

Tuple-at-a-Time Model

Query execution is fulfilled by a query engine called Bobo, which uses the tuple-at-a-time model.

Query Interface

Custom API

*Browsing Query Language* (BQL) is supported by SenseiDB, which has the similar syntax to SQL. Besides those existing clauses in SQL, BQL introduces the "BROWSE BY" clause to support faceted search and navigation. This is the biggest feature of BQL.

Storage Architecture

Disk-oriented

SenseiDB uses a disk-oriented distributed storage architecture.

Storage Model

N-ary Storage Model (Row/Record)

A SenseiDB instance is a table of data that is organized into columns. The attributes of a table is stored as metadata, and each column may belong to one of the supported types: string, int, long, short, float, double, char, date, text.

Stored Procedures

Not Supported

System Architecture

Shared-Nothing

The entire database is partitioned into a number of shards. Each shard is replicated across N nodes so that there might be more than one shards in a single node. There is not a master node in the system and each node is independent. Upcoming requests go through a separate load balancer to decide the nodes to request.

SenseiDB Logo
Website

http://senseidb.github.io/sensei/

Source Code

https://github.com/linkedin/sensei

Tech Docs

http://senseidb.github.io/sensei/overview.html

Developer

LinkedIn, Xiaomi

Country of Origin

US

Start Year

2012

End Year

2013

Project Type

Open Source

Written in

Java

Supported languages

Java, Python

Operating Systems

All OS with Java VM

Licenses

Apache v2