Module: Picky::Backends::Redis::NonScripting

Defined in:
lib/picky/backends/redis.rb

Overview

Does not use Lua scripting, < Redis 2.6.

Instance Method Summary collapse

Instance Method Details

#ids(combinations, amount, offset) ⇒ Object 



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# File 'lib/picky/backends/redis.rb', line 262

def ids combinations, amount, offset
  identifiers = identifiers_for combinations

  result_id = generate_intermediate_result_id

  # Little optimization.
  #
  if identifiers.size > 1
    # Intersect and store.
    #
    intersected = client.zinterstore result_id, identifiers

    # Return clean and early if there has been no intersection.
    #
    if intersected.zero?
      client.del result_id
      return []
    end

    # Get the stored result.
    #
    results = client.zrange result_id, offset, (offset + amount)

    # Delete the stored result as it was only for temporary purposes.
    #
    # Note: I could also not delete it, but that
    #       would not be clean at all.
    #
    client.del result_id
  else
    results = client.zrange identifiers.first, offset, (offset + amount)
  end

  results
end