Taming the Complexity of Database Queries in Node.js

Hi, I'm John Fawcett

  • Dev@Goodybag
  • Built Goodybag's REST API with Node + Postgres
  • Not a DB expert, but I'm alright
Ok, kids. Let's go!

Why is Mongo Great?

  • JavaScript all the way down
  • Results are already JSON
  • Mongo shell is nice
  • Fast to setup
  • Well-documented
  • Queries built with JS primitives
  • Great for flex schemas
  • Learnboost did it
Code Sample
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Why does Mongo Suck?

  • No transactions
  • No joining
  • Database locking on like EVERYTHING
  • Non-trivial use-cases can be really slow
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Enter Postgres

Take the good, drop the bad

  • Relational
  • Transactions
  • JSON Support (flexible schemas)
  • Pretty darn fast (Page 39)
  • Widely used
What does it look like in node?
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SQL Tools

Don't write SQL strings in JS - Use:

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MongoSQL: What is it good for?

  • Not for easier SQL writing
  • It's for easier SQL reasoning inside of code
  • Your query becomes a value
  • Robust helper interface - your use-case is supported
  • Makes SQL composable and extensible
  • Helps tame queries like this
  • Helps you build your own tools when rolling your own is necessary
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Closing the Gaps and the Mental Leaps

  • MoSQL brings it back to JavaScript
  • Further decreases the mental gap between database and code
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What About ORMS?

  • MoSQL && ORMs not mutually exclusive
  • Sequelize.js - great monolithic choice
    • As there are often use cases in which it is just easier to execute raw / already prepared SQL queries, you can utilize the function sequelize.query
  • The need for an ORM is partially obviated in JS
  • Often, ORMs complect a situation more than simplify it
  • MoSQL can help you build your own ORM
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Example: When SQL Attacks

  • New features need to be added
  • How do we organize monsterous queries?
    • Proper logic chunking
  • Maybe your API needs to be slightly denormalized
    • Without degrading performance
  • In Sequelize, you'd probably write batch queries (with bad performance)
    • Use-case isn't supported, so you end up writing SQL anyway
  • Use MoSQL to help
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  • In the end, I use a combination of Silly and MoSQL
  • Use Postgres and MoSQL - close the mental gap
  • MoSQL is super extensible, composable, and supports a lot of use cases
  • Database queries as a simple, reflectable data structure
  • Helps build your own tools and separate your logic
    • Recent project: generic middleware and ORM-ish tools