Class: Dynamoid::AdapterPlugin::Query

Inherits:
Object
  • Object
show all
Defined in:
lib/dynamoid/adapter_plugin/query.rb

Constant Summary collapse

OPTIONS_KEYS = 
[
  :limit, :hash_key, :hash_value, :range_key, :consistent_read, :scan_index_forward,
  :select, :index_name, :batch_size, :exclusive_start_key, :record_limit, :scan_limit
]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(client, table, opts = {}) ⇒ Query

Returns a new instance of Query.



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# File 'lib/dynamoid/adapter_plugin/query.rb', line 11

def initialize(client, table, opts = {})
  @client = client
  @table = table

  opts = opts.symbolize_keys
  @options = opts.slice(*OPTIONS_KEYS)
  @conditions = opts.except(*OPTIONS_KEYS)
end

Instance Attribute Details

#client ⇒ Object (readonly)

Returns the value of attribute client.



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# File 'lib/dynamoid/adapter_plugin/query.rb', line 9

def client
  @client
end

#conditions ⇒ Object (readonly)

Returns the value of attribute conditions.



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# File 'lib/dynamoid/adapter_plugin/query.rb', line 9

def conditions
  @conditions
end

#options ⇒ Object (readonly)

Returns the value of attribute options.



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# File 'lib/dynamoid/adapter_plugin/query.rb', line 9

def options
  @options
end

#table ⇒ Object (readonly)

Returns the value of attribute table.



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# File 'lib/dynamoid/adapter_plugin/query.rb', line 9

def table
  @table
end

Instance Method Details

#call ⇒ Object 



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# File 'lib/dynamoid/adapter_plugin/query.rb', line 20

def call
  request = build_request

  Enumerator.new do |yielder|
    record_count = 0
    scan_count = 0

    backoff = Dynamoid.config.backoff ? Dynamoid.config.build_backoff : nil

    loop do
      # Adjust the limit down if the remaining record and/or scan limit are
      # lower to obey limits. We can assume the difference won't be
      # negative due to break statements below but choose smaller limit
      # which is why we have 2 separate if statements.
      # NOTE: Adjusting based on record_limit can cause many HTTP requests
      # being made. We may want to change this behavior, but it affects
      # filtering on data with potentially large gaps.
      # Example:
      #    User.where('created_at.gte' => 1.day.ago).record_limit(1000)
      #    Records 1-999 User's that fit criteria
      #    Records 1000-2000 Users's that do not fit criteria
      #    Record 2001 fits criteria
      # The underlying implementation will have 1 page for records 1-999
      # then will request with limit 1 for records 1000-2000 (making 1000
      # requests of limit 1) until hit record 2001.
      if request[:limit] && record_limit && record_limit - record_count < request[:limit]
        request[:limit] = record_limit - record_count
      end
      if request[:limit] && scan_limit && scan_limit - scan_count < request[:limit]
        request[:limit] = scan_limit - scan_count
      end

      response = client.query(request)

      yielder << response

      record_count += response.count
      break if record_limit && record_count >= record_limit

      scan_count += response.scanned_count
      break if scan_limit && scan_count >= scan_limit

      if response.last_evaluated_key
        request[:exclusive_start_key] = response.last_evaluated_key
      else
        break
      end

      backoff.call if backoff
    end
  end
end