Implement an optimized database for large-scale data that requires numerous aggregate queries. My choice was Clickhouse due to its low storage cost and very fast aggregate query results (based on benchmarks).

Main Challenges: The primary challenge I faced in the project was constructing complex queries on large data sets for certain requirements, such as:

• Calculating the total access time based on category, user, and time frame, ensuring that the times do not overlap (e.g., if request 1 is from 1 PM to 5 PM and request 2 is from 2 PM to 6 PM, the total time is from 1 PM to 6 PM).
• Splitting requests that span multiple time frames or days (e.g., a request from 10 PM to 4 AM is counted as two sessions, one for the night before and one for the early morning of the next day).

Docker, Clickhouse, Python Flask

Developing the automatic drawing generation tool, followed by taking over, managing, and maintaining the website.

Main Challenges: The primary challenge of the project was the short time frame (about 1-2 months) required to learn CAD knowledge, become proficient with AutoCAD tools, and familiarize myself with CAD drawing libraries in Python.

Python Flask, ezdxf, Postgres, Docker, GitlabCI

Developed an Internal Document Management Website:

• Created a web platform for managing company documents, featuring functionalities akin to Google Drive and OneDrive.
• Implemented essential features for document storage, retrieval, and sharing within the company.

Implemented Flexible User Permissions:

• Designed a permission system that provides flexible user permissions for various organizational levels, including teams, departments, and the entire company.
• Developed inheritance-based permission settings following a folder hierarchy, ensuring that permissions cascade appropriately from parent folders to subfolders.

Integrated with Internal File System:

• Seamlessly integrated data synchronization with the internal file system hosted on a Synology NAS.
• Ensured that permission information is consistently synchronized with the internal file system, maintaining security and access control across all platforms.

The main challenge I faced in the project was being the sole developer, specifically handling backend tasks, and ensuring the implementation of numerous complex business requirements such as permission control, item management, parent-child relationships between directories/files, user groups, hierarchy levels, and other emerging functions during use. To ensure stable quality and a short development timeline, I utilized JHipster, an automated code generation tool based on the ERD of the database. My tasks involved designing the database according to the business requirements, using JHipster, and making necessary adjustments to fit the project.

Java Spring Boot, Postgres, ReactJS, Redis, RabbitMQ, Docker, GitlabCI

Developed an SSO (Single Sign-On) authentication service as an intermediary to authenticate SSO tokens for other services. Implemented the service using Vert.X for API implementation and Redis for caching purposes.

Java Vert.X, Redis, Docker

Developed a Geospatial Data Management Website:

• Created a web platform specifically designed for storing and managing geospatial data captured and compiled using dedicated drones.
• Incorporated functionalities that allow users to simulate and interact with geospatial data, providing experiences similar to those offered by Google Earth.

Simulation and Interactive Features:

• Implemented tools and features that enable users to simulate various geospatial scenarios, enhancing the interactive experience.
• Developed interactive maps and visualizations that allow users to explore geospatial data with ease and precision.

Optimization for Web and Mobile Platforms:

• Ensured that the website is fully optimized for both web and mobile platforms, providing a seamless user experience across different devices.
• Utilized responsive design techniques to adapt the website layout and functionalities to various screen sizes and resolutions.

Integration with Drone Data:

• Developed mechanisms for the efficient capture and compilation of geospatial data from dedicated drones.
• Integrated this data seamlessly into the website, allowing for real-time updates and accurate geospatial representations.

Spring Boot, VueJS, Postgres, Redis, Leaflet, Jenkins,...

• Managing the database of product catalogs, including basic information such as names, details, inventory, and product options like size, weight, color, etc.
• Additionally, I am tasked with developing APIs to support product search within the database (utilizing Elastic Search) and providing automatic completion suggestions based on existing product data.

Java Spring Boot, Postgres, ReactJS, Redis, Elastic Search,...

Maintenance, bug fixing, and migrating the data storage from Cassandra to Google's BigTable.

SpringBoot, Postgres, Redis, Cassandra, BigTable (Google)