nosql db: a bit on mongo and cassandra

nosql

• has high learning curve if you're coming from sql because of its non-sql syntax
• quick when handling large sets of data
• hard to generate relational reports
• may/may not be useful for your setup

mongodb vs cassandra

• c++ vs java based
• mongodb's indexes are currently more flexible; you need to index columns before you can query by them
• cassandra has single key value columns
• write more than read = cassandra; write is more complicated with mongo
• spatial in mongo seems easier
• mongodb is better documented and has more driver support; cassandra only has pyhton and php drivers

on mongodb

• ideal for multiple servers setup
• reported to have high memory usage even if it's idle because of its caching function
• using more than one geo index per collection will produce undesirable behavior
• can use near, geoNear, bounds queries
• uses port 27017

things to try for simple comparison with sql db:

a. search - speed comparison when compared to mysql
     - speed diff during exact text search is not noticable when limited to 1 result
     - large speed diff during exact text search when not limited to 1 result
     - no full text search rather uses multikeys or tags

b. replication
     - master - slave setup can be done using 2 machines
     - restore primary failure - can set secondary as primary
     - restore secondary failure - just clear new secondary
     - *try copying data from secondary to restore primary as primary