Class: Droonga::DistributedSearchPlanner::QueryTransformer

Inherits:
Object
  • Object
show all
Defined in:
lib/droonga/plugin/planner/distributed_search_planner.rb

Constant Summary collapse

ASCENDING_OPERATOR = 
"<"
DESCENDING_OPERATOR = 
">"

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(query) ⇒ QueryTransformer

Returns a new instance of QueryTransformer.



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 100

def initialize(query)
  @query = query
  @output = @query["output"]
  @reducers = {}
  @mappers = {}
  @output_records = true
  transform!
end

Instance Attribute Details

#mappers ⇒ Object (readonly)

Returns the value of attribute mappers.



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 98

def mappers
  @mappers
end

#reducers ⇒ Object (readonly)

Returns the value of attribute reducers.



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 98

def reducers
  @reducers
end

Instance Method Details

#array_style_attributes ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 303

def array_style_attributes
  attributes = @output["attributes"] || []
  if attributes.is_a?(Hash)
    attributes.keys.collect do |key|
      attribute = attributes[key]
      case attribute
      when String
        {
          "label"  => key,
          "source" => attribute,
        }
      when Hash
        attribute["label"] = key
        attribute
      end
    end
  else
    attributes
  end
end

#build_count_mapper_and_reducer! ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 234

def build_count_mapper_and_reducer!
  return unless @output["elements"].include?("count")

  @reducers["count"] = {
    "type" => "sum",
  }
  if unifiable?
    @query["sortBy"]["limit"] = -1 if @query["sortBy"].is_a?(Hash)
    @output["limit"] = -1
    mapper = {
      "target" => "records",
    }
    unless @output["elements"].include?("records")
      @records_limit = -1
      @output["elements"] << "records"
      @output["attributes"] ||= ["_key"]
      @output_records = false
    end
    @mappers["count"] = mapper
  end
end

#build_records_mapper_and_reducer! ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 256

def build_records_mapper_and_reducer!
  # Skip reducing phase for a result with no record output.
  return if !@output["elements"].include?("records") || @records_limit.zero?

  # Append sort key attributes to the list of output attributes
  # temporarily, for the reducing phase. After all extra columns
  # are removed on the gathering phase.
  final_attributes = output_attribute_names
  update_output_attributes!

  @reducers["records"] = build_records_reducer

  mapper = {}
  if @output_records
    mapper["format"]     = @records_format unless @records_format == "simple"
    mapper["attributes"] = final_attributes unless final_attributes.empty?
    mapper["offset"]     = @records_offset unless @records_offset.zero?
    mapper["limit"]      = @records_limit unless @records_limit.zero?
  else
    mapper["no_output"] = true
  end
  @mappers["records"] = mapper
end

#build_records_reducer ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 359

def build_records_reducer
  attributes = source_column_names
  key_column_index = attributes.index("_key")

  operators = @sort_keys.collect do |sort_key|
    operator = ASCENDING_OPERATOR
    if sort_key[0] == "-"
      operator = DESCENDING_OPERATOR
      sort_key = sort_key[1..-1]
    end
    {
      "operator" => operator,
      "column"   => attributes.index(sort_key),
    }
  end

  reducer = {
    "type"      => "sort",
    "operators" => operators,
  }
  if unifiable? && !key_column_index.nil?
    reducer["key_column"] = key_column_index
  end

  # On the reducing phase, we apply only "limit". We cannot apply
  # "offset" on this phase because the collector merges a pair of
  # results step by step even if there are three or more results.
  # Instead, we apply "offset" on the gathering phase.
  reducer["limit"] = @output["limit"]

  reducer
end

#calculate_offset_and_limit! ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 126

def calculate_offset_and_limit!
  @original_sort_offset = sort_offset
  @original_output_offset = output_offset
  @original_sort_limit = sort_limit
  @original_output_limit = output_limit

  calculate_sort_offset!
  calculate_output_offset!

  # We have to calculate limit based on offset.
  # <A, B = limited integer (0...MAXINT)>
  # | sort limit | output limit | => | worker's sort limit      | worker's output limit   | final limit |
  # =============================    ====================================================================
  # | UNLIMITED  | UNLIMITED    | => | UNLIMITED                | UNLIMITED               | UNLIMITED   |
  # | UNLIMITED  | B            | => | final_offset + B         | final_offset + B        | B           |
  # | A          | UNLIMITED    | => | final_offset + A         | final_offset + A        | A           |
  # | A          | B            | => | final_offset + max(A, B) | final_offset + min(A, B)| min(A, B)   |

  # XXX final_limit and final_offset calculated in many times

  @records_offset = final_offset
  @records_limit = final_limit

  updated_sort_limit = nil
  updated_output_limit = nil
  if final_limit == UNLIMITED
    updated_output_limit = UNLIMITED
  else
    if rich_sort?
      updated_sort_limit = final_offset + [sort_limit, output_limit].max
    end
    updated_output_limit = final_offset + final_limit
  end

  if updated_sort_limit && updated_sort_limit != @query["sortBy"]["limit"]
    @query["sortBy"]["limit"] = updated_sort_limit
  end
  if updated_output_limit && @output["limit"] && updated_output_limit != @output["limit"]
    @output["limit"] = updated_output_limit
  end
end

#calculate_output_offset! ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 200

def calculate_output_offset!
  @output["offset"] = 0 if have_records? && @output["offset"]
end

#calculate_sort_offset! ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 168

def calculate_sort_offset!
  # Offset for workers must be zero, because we have to apply "limit" and
  # "offset" on the last gathering phase instead of each reducing phase.
  if rich_sort?
    @query["sortBy"]["offset"] = 0
  end
end

#final_limit ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 208

def final_limit
  if @original_sort_limit == UNLIMITED && @original_output_limit == UNLIMITED
    UNLIMITED
  else
    if @original_sort_limit == UNLIMITED
      @original_output_limit
    elsif @original_output_limit == UNLIMITED
      @original_sort_limit
    else
      [@original_sort_limit, @original_output_limit].min
    end
  end
end

#final_offset ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 204

def final_offset
  @original_sort_offset + @original_output_offset
end

#have_records? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 222

def have_records?
  @output["elements"].include?("records")
end

#output_attribute_names ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 280

def output_attribute_names
  attributes = @output["attributes"] || []
  if attributes.is_a?(Hash)
    attributes.keys
  else
    attributes.collect do |attribute|
      if attribute.is_a?(Hash)
        attribute["label"] || attribute["source"]
      else
        attribute
      end
    end
  end
end

#output_limit ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 196

def output_limit
  @output["limit"] || 0
end

#output_offset ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 184

def output_offset
  @output["offset"] || 0
end

#rich_sort? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 226

def rich_sort?
  @query["sortBy"].is_a?(Hash)
end

#sort_attribute_names ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 344

def sort_attribute_names
  sort_attributes = @sort_keys.collect do |key|
    key = key[1..-1] if key[0] == "-"
    key
  end
  attributes = source_column_names
  sort_attributes.reject! do |attribute|
    attributes.include?(attribute)
  end
  sort_attributes
end

#sort_limit ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 188

def sort_limit
  if rich_sort?
    @query["sortBy"]["limit"] || UNLIMITED
  else
    UNLIMITED
  end
end

#sort_offset ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 176

def sort_offset
  if rich_sort?
    @query["sortBy"]["offset"] || 0
  else
    0
  end
end

#source_column_names ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 324

def source_column_names
  attributes = @output["attributes"] || []
  if attributes.is_a?(Hash)
    attributes_hash = attributes
    attributes = []
    attributes_hash.each do |key, attribute|
      attributes << attribute["source"] || key
    end
    attributes
  else
    attributes.collect do |attribute|
      if attribute.is_a?(Hash)
        attribute["source"] || attribute["label"]
      else
        attribute
      end
    end
  end
end

#transform! ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 109

def transform!
  # The collector module supports only "simple" format search results.
  # So we have to override the format and restore it on the gathering
  # phase.
  @records_format = @output["format"] || "simple"
  if @output["format"] && @output["format"] != "simple"
    @output["format"] = "simple"
  end

  @sort_keys = @query["sortBy"] || []
  @sort_keys = @sort_keys["keys"] || [] if @sort_keys.is_a?(Hash)

  calculate_offset_and_limit!
  build_count_mapper_and_reducer!
  build_records_mapper_and_reducer!
end

#unifiable? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 230

def unifiable?
  @output["unifiable"]
end

#update_output_attributes! ⇒ Object 



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# File 'lib/droonga/plugin/planner/distributed_search_planner.rb', line 295

def update_output_attributes!
  @output["attributes"] = array_style_attributes
  @output["attributes"] += sort_attribute_names
  if unifiable? && !source_column_names.include?("_key")
    @output["attributes"] << "_key"
  end
end