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@jwhiting
jwhiting / warmup.rb
Created May 14, 2018 22:00
Warming up EBS volumes on RDS replicas/snapshots (ruby script)
#!/usr/bin/env ruby
require 'pg'
=begin
when creating a postgres db replica in RDS, or restoring from a snapshot, the
underlying EBS volume of the new instance must be initialized by reading every
block, otherwise the blocks will be lazy-initialized by production queries
which will be extremely latent. (i've seen normally 50ms queries take 30s in