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Research on Sharding, Reading Octopus

Reference

• If you have HashWithIndifferentAccess, just use it?
• ActiveRecord::VERSION::MAJOR and MINOR is a thing to check versions.
• Logger method:

def self.logger
  if defined?(Rails.logger)
    @logger ||= Rails.logger
  else
    @logger ||= Logger.new($stderr)
  end
end

• Hooks into ActiveRecord::Base.connection, creates an Octopus::Proxy
• Inclusion method:

def self.included(base)
  base.extend(ClassMethods)
end

How would I implement separate databases for reading and writing operations?

Reference

• Read/write master databases and read-only slaves are a common pattern, especially for big applications doing mostly read accesses/data warehouses.
• It allows you to scale and to tune the databases differently, for either efficient reads or efficient writes.
• It really depends on what you are trying to achieve by having two databases.
  • If it is for performance reasons (which i suspect it may be) i would suggest you look into denormalizing the read-only database as needed for performance.
  • If performance isn’t an issue then I wouldn’t mess with the read-only schema.
• I’ve worked on similar systems where there would be a read/write database that was only lightly used by administrative users. That database would then be replicated to the read only database during a nightly process.

Slow Rails Queries

Reference

• New Relic, PgHero to track down query bottlenecks in the applications.
• Seq Scans: Means PG needs to scan a table row by row to find matching entries.
• Seed local database to mimic production. Perform benchmarks on a local computer, with settings resembling a real production site.
• Siege for local benchmarks.

Musings/Links

• Bootstrap 4 File Input: I fixed this with JQuery.
• Capybara upload file: Use File.absolute_path.
• You need type: feature to enable Capybara methods (RSpec).
• When creating an index over multiple columns, put the column with least variance first.
• Getting a file’s MIME type using Rack. Rack::Mime.mime_type(File.extname(filename))
• Apparently you shouldn’t offset when using an index?