Carry out empirical work that extends the research work of my honours thesis: Overleaf Link
Tasks include coding experimental harnesses, applying additional workloads to installations of MongoDB on cloud-hosted services, measuring query execution time, visualizing ties of query plan choices, analysis overhead of the FPTP approach, storage of code data and outcomes in appropriate stores, and producing reports and charts on the results.
The results and findings of this project have the following contributions towards understanding the nature of the MongoDB query optimizer:
- I made a VLDB submission
- In the above submission, I propose an innovative way to evaluate and visualize the impact on query performance of an optimizer’s choices. By using this approach, I identify places where the MongoDB query optimizer chooses sub-optimal query plans. My approach could form the basis of an automated regression testing tool to verify that the query planner in MongoDB improves over time.
- I identify causes of the preference bias of FPTP, in which index scans are systematically chosen even when a collection scan would run faster. I fix the problem. Different versions of the MongoDB source code are available for download and inspection.
- The query plan visualization tool can visualize ties (i.e. query plans with similar execution time)
Code for all experiments and results
This tool aims at evaluating the effectiveness of Mongodb query optimizer. We define query optimizer effectiveness as the capability of the query optimizer to consistently choose the best execution plan among all alternatives. This tool is capable of...
- Populate a MongoDB database with customizable workload.
- Visualize MongoDB's choices of query plan and their performance.
- Visualize ties (i.e. query plans that has similar execution time)
- Visualize the overhead of the FPTP query optimization.
Please follow the steps below to run the code. Please note that some steps cannot be skipped. It is strongly recommended to execute the code step by step according to the instructions. Otherwise, you may encounter errors.
- Deploy different versions of MongoDB on AWS instances. (Includes links to modified MongoDB source code)
> Instructions - Prerequisites and suggested settings.
> Instructions - Run the experiment which visualize query plans and their performance.
> Instructions - Visualize ties (i.e. query plans that has similar execution time).
> Instructions - Measure overhead and evaluate results.
> Instructions