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Get all records from a particular collection once you're switched to a particular db
- 'db.<collection_name>.find()'
Check if a field contains a string
- db.getCollection('collection_name').find({"Party1": {$regex : ".*similarly situated.*"}})
Find records by non-existence of a field:
- db.mycollection.find({ "price" : { "$exists" : false } })
Find a record by its id:
- db.collection_name.find({"_id": ObjectId("587862a88362593254464c69")})
  - So you can find it by the id's string value, but you need to wrap the string with ObjectId()

Neo4j

Summary
- It seems like Neo4j is helpful for making join-heavy queries orders-of-magnitude faster.
Links
- http://stackoverflow.com/questions/19570654/do-graph-databases-deprecate-relational-databases
- https://groups.google.com/forum/#!topic/neo4j/mts6H9Py-2I
- https://neo4j.com/developer/graph-db-vs-rdbms/
  - "If you use many-to-many relationships, you have to introduce a JOIN table (or junction table) that holds foreign keys of both participating tables which further increases join operation costs. Those costly join operations are usually addressed by denormalising data to reduce the number of joins necessary."
  - "This ability of pre-materializing relationships into database structures allows Neo4j to provide performances of several orders of magnitude, especially for join heavy queries, the minutes to milliseconds advantage that many users leverage."

PostGIS
- This was one of the major reasons Krieger and Systrom went with Postgres over MySQL. (Source)

Get the number of rows in all tables in a database.
- SELECT schemaname,relname,n_live_tup
  FROM pg_stat_user_tables
  ORDER BY n_live_tup DESC;