Module: Switchman::ActiveRecord::Relation

Defined in:
lib/switchman/active_record/relation.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.prepended(klass) ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 6

def self.prepended(klass)
  klass::SINGLE_VALUE_METHODS.concat %i[shard shard_source]
end

Instance Method Details

#activate(unordered: false, &block) ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 103

def activate(unordered: false, &block)
  shards = all_shards
  if Array === shards && shards.length == 1
    if shards.first == DefaultShard || shards.first == Shard.current(klass.connection_class_for_self)
      yield(self, shards.first)
    else
      shards.first.activate(klass.connection_class_for_self) { yield(self, shards.first) }
    end
  else
    result_count = 0
    can_order = false
    result = Shard.with_each_shard(shards, [klass.connection_class_for_self]) do
      # don't even query other shards if we're already past the limit
      next if limit_value && result_count >= limit_value && order_values.empty?

      relation = shard(Shard.current(klass.connection_class_for_self), :to_a)
      # do a minimal query if possible
      relation = relation.limit(limit_value - result_count) if limit_value && !result_count.zero? && order_values.empty?

      shard_results = relation.activate(&block)

      if shard_results.present? && !unordered
        can_order ||= can_order_cross_shard_results? unless order_values.empty?
        raise OrderOnMultiShardQuery if !can_order && !order_values.empty? && result_count.positive?

        result_count += shard_results.is_a?(Array) ? shard_results.length : 1
      end
      shard_results
    end

    result = reorder_cross_shard_results(result) if can_order
    result.slice!(limit_value..-1) if limit_value
    result
  end
end

#can_order_cross_shard_results? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/switchman/active_record/relation.rb', line 139

def can_order_cross_shard_results?
  # we only presume to be able to post-sort the most basic of orderings
  order_values.all? { |ov| ov.is_a?(::Arel::Nodes::Ordering) && ov.expr.is_a?(::Arel::Attributes::Attribute) }
end

#clone ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 16

def clone
  result = super
  result.shard_value = Shard.current(klass ? klass.connection_class_for_self : :primary) unless shard_value
  result
end

#create(&block) ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 35

def create(*, &block)
  primary_shard.activate(klass.connection_class_for_self) { super }
end

#create!(&block) ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 39

def create!(*, &block)
  primary_shard.activate(klass.connection_class_for_self) { super }
end

#explain ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 47

def explain
  activate { |relation| relation.call_super(:explain, Relation) }
end

#find_ids_in_ranges(options = {}) ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 70

def find_ids_in_ranges(options = {})
  is_integer = columns_hash[primary_key.to_s].type == :integer
  loose_mode = options[:loose] && is_integer
  # loose_mode: if we don't care about getting exactly batch_size ids in between
  # don't get the max - just get the min and add batch_size so we get that many _at most_
  values = loose_mode ? 'MIN(id)' : 'MIN(id), MAX(id)'

  batch_size = options[:batch_size].try(:to_i) || 1000
  quoted_primary_key = "#{klass.connection.quote_local_table_name(table_name)}.#{klass.connection.quote_column_name(primary_key)}"
  as_id = ' AS id' unless primary_key == 'id'
  subquery_scope = except(:select).select("#{quoted_primary_key}#{as_id}").reorder(primary_key.to_sym).limit(loose_mode ? 1 : batch_size)
  subquery_scope = subquery_scope.where("#{quoted_primary_key} <= ?", options[:end_at]) if options[:end_at]

  first_subquery_scope = if options[:start_at]
                           subquery_scope.where("#{quoted_primary_key} >= ?",
                                                options[:start_at])
                         else
                           subquery_scope
                         end

  ids = connection.select_rows("SELECT #{values} FROM (#{first_subquery_scope.to_sql}) AS subquery").first

  while ids.first.present?
    ids.map!(&:to_i) if is_integer
    ids << (ids.first + batch_size) if loose_mode

    yield(*ids)
    last_value = ids.last
    next_subquery_scope = subquery_scope.where(["#{quoted_primary_key}>?", last_value])
    ids = connection.select_rows("SELECT #{values} FROM (#{next_subquery_scope.to_sql}) AS subquery").first
  end
end

#initialize ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 10

def initialize(*, **)
  super
  self.shard_value = Shard.current(klass ? klass.connection_class_for_self : :primary) unless shard_value
  self.shard_source_value = :implicit unless shard_source_value
end

#load(&block) ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 51

def load(&block)
  if !loaded? || (::Rails.version >= '7.0' && scheduled?)
    @records = activate { |relation| relation.send(:exec_queries, &block) }
    @loaded = true
  end

  self
end

#merge ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 22

def merge(*)
  relation = super
  if relation.shard_value != shard_value && relation.shard_source_value == :implicit
    relation.shard_value = shard_value
    relation.shard_source_value = shard_source_value
  end
  relation
end

#new(&block) ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 31

def new(*, &block)
  primary_shard.activate(klass.connection_class_for_self) { super }
end

#reorder_cross_shard_results(results) ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 144

def reorder_cross_shard_results(results)
  results.sort! do |l, r|
    result = 0
    order_values.each do |ov|
      if l.is_a?(::ActiveRecord::Base)
        a = l.attribute(ov.expr.name)
        b = r.attribute(ov.expr.name)
      else
        a, b = l, r
      end
      next if a == b

      if a.nil? || b.nil?
        result = 1 if a.nil?
        result *= -1 if ov.is_a?(::Arel::Nodes::Descending)
      else
        result = a <=> b
      end

      result *= -1 if ov.is_a?(::Arel::Nodes::Descending)
      break unless result.zero?
    end
    result
  end
end

#to_sql ⇒ Object 



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# File 'lib/switchman/active_record/relation.rb', line 43

def to_sql
  primary_shard.activate(klass.connection_class_for_self) { super }
end