MongoDB to MySQL the How and the Why
summary
A large Rails social project starts on MongoDB with MongoMapper, accumulates thousands of users and complex linked social graphs, then migrates to MySQL because document storage forces manual joins and slows development. The team exports with mongoexport to CSV, converts and imports with batch inserts, LOAD DATA INFILE and active_record_import, uses 10k–20k batch sizes, keeps a Legacy ID column to reconcile Mongo GUIDs, accepts about two hours downtime, and ends up with faster iteration after MongoDB → MySQL conversion.
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chapters (7)
- 0:00Introduction
- 8:28Why diaspora chose MongoDB
- 16:43Social data is relational
- 24:04Development friction with MongoDB
- 27:54Mapper problems in practice
- 28:16Migrating to MySQL
- 35:08Q&A
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