MiGration Scripts

A Simple Show and Tell Lighting Talk

Goals

Short review
Show a migration script with aggregation
Talk about Migration scripts

Migration Strategies

Feature Switches
Migration Scripts
Pay As You Go
Versioning

Aggregation Framework

A means to calculate aggregated values

without using map-reduce

The Pieces

Pipeline

Pipes objects through a unix pipe like fashion

Expressions

Similar to SQL statements - allows document manipulation and calculations

Implementations are done with the Mongo Ruby Driver

Your examples may look different or you might use

ORMs like Mongoid or MongoMapper (Ruby)

The Code

cmd = { aggregate: 'assessments',
        pipeline: [
          {
            '$project' => {
              :_id => 0,
              :user_id => 1,
              :organization_id => 1,
              :assessment_id => "$_id",
              :supplemental_question_ids => 1,
              :question_ids => 1,
              :response_count => 1,
              :date => 1,
              :end_date => 1,
              :released => 1,
              :viewing_key => 1,
            }
          }
        ]
      }