IoTDB (Internet of Things Database) is a specialized database management system for time series data generated by network of IoT devices with low computational power. It targets at workload that has high-frequency of data write, large-volume data storage, and complex analytical queries.


IotDB is a project started in 2017 by Prof. Jianmin Wang’s group in School of Software of Tsinghua University and China’s National Engineering laboratory for Big Data Software. The project entered incubation by Apache Incubator on [Nov. 18th, 2018]( The project evolves from a prior project of the same group called TsFile. TsFile is a columnar storage format optimized for storing time series data. IoTDB uses TsFile as its underlying storage format.

Query Interface

Custom API

SQL-like customized query language.

Concurrency Control

Not Supported

As IoTDB does not support transaction, it has a bare-bone concurrency control implementation with read locks and write locks. Their implementation does not follow a Two-Phase Locking protocol, as there are cases where a lock is acquired after another lock is released previously in the same function, and example is included in citation 1 of this section. IoTDB uses Java's native ReentrantReadWriteLock in the implementation. To avoid access conflict when concurrently reading or writing to user or role, IoTDB has HashLock implemented for user manager and lock manager. A HashLock lock is a wrapper around a fixed number of ReentrantReadWriteLock locks. By default, it initializes with an array of 100 ReentrantReadWriteLock locks. Each applicable database object corresponds to one lock in the array, according to hash value of the object. This avoids conflicts resulted from concurrent access of same database object, user or role in this case, while in the same time limit the amount of resource needed to managing those locks.


Logical Logging

Physical query plans are serialized and stored as logs. Write-Ahead-Logging with only REDO records.

Isolation Levels


Query Execution

Tuple-at-a-Time Model

Stored Procedures


SQL-like PREPARE statement is supported.

Storage Architecture


Foreign Keys

Not Supported

Data Model

Column Family

System Architecture


The overall IoTDB follows a client-server architecture. IoTDB client resides in the sensors(IoT devices) of the system, handling data collection and sending data to IoTDB server. Client can sync its data collected every user-configured interval with the server using Sync Tool; this allows data collected by the sensor to constantly being persisted in server, where the data can then be used for native query or shipped to other open-source platform for data analysis. Currently support single node server deployment. The group is working in progress to support shared-nothing cluster. IoTDB currently supports writing to HDFS.

Query Compilation

Code Generation

Apache Thrift

IoTDB Logo

Source Code

Tech Docs


Tsinghua University

Country of Origin


Start Year


Project Type

Academic, Open Source

Written in


Supported languages

Java, Python

Compatible With

Hive, Spark SQL

Operating Systems

Linux, OS X, Windows


Apache v2