picture of Brice Chardin
brice.chardin at ensma.fr

Brice Chardin

I am an assistant professor at ENSMA, LIAS laboratory, Data Engineering team.

This site is mainly dedicated to software projects I am or have been working on; it provides instructions for downloading, installing and using them.


Chronos is a DBMS designed to manage time series data on flash memories with insert-heavy workloads. The original use case is the collection of sensor data in hydroelectric power stations at EDF. Tests performed in collaboration with the EDF Hydraulic Engineering Center under operational conditions showed an improvement by a factor of 9 over the solution used in production, based on MySQL.

In less specific terms, Chronos is designed to perform well when insertion sequences have strictly increasing keys. Several of such sequences can occur concurrently. Additionally, the storage device should have good random read and sequential write performance, as do most flash memories.


We defined a benchmark for historization systems, a class of DBMS designed to manage industrial process data. This benchmark is inspired by EDF use cases, and defines twelve queries representative of EDF practices. It has been used to test a data historian, InfoPlus.21; a RDBMS, MySQL; and two ordered key-value stores, Berkeley DB and Chronos.


RQL stands for Rule Query Language. It is a SQL-like pattern mining language that extends and generalizes functional dependencies to new and unexpected rules. A web-based prototype has been made available for research and educational purposes.