PERF: Active Record #pluck is twice faster

PERF: SqlBuilder bypasses AR converters and uses PG directly
This commit is contained in:
Sam 2015-05-13 16:45:59 +10:00
parent e81f122a3f
commit 51d82fc25d
4 changed files with 143 additions and 34 deletions

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@ -0,0 +1,108 @@
# Speeds up #pluck so its about 2.2x faster, importantly makes pluck avoid creation of a slew
# of AR objects
require_dependency 'sql_builder'
class ActiveRecord::Relation
# class RailsDateTimeDecoder < PG::SimpleDecoder
# def decode(string, tuple=nil, field=nil)
# if Rails.version >= "4.2.0"
# @caster ||= ActiveRecord::Type::DateTime.new
# @caster.type_cast_from_database(string)
# else
# ActiveRecord::ConnectionAdapters::Column.string_to_time string
# end
# end
# end
#
# class ActiveRecordTypeMap < PG::BasicTypeMapForResults
# def initialize(connection)
# super(connection)
# rm_coder 0, 1114
# add_coder RailsDateTimeDecoder.new(name: "timestamp", oid: 1114, format: 0)
# # we don't need deprecations
# self.default_type_map = PG::TypeMapInRuby.new
# end
# end
#
# def self.pg_type_map
# conn = ActiveRecord::Base.connection.raw_connection
# @typemap ||= ActiveRecordTypeMap.new(conn)
# end
class ::ActiveRecord::ConnectionAdapters::PostgreSQLAdapter
if Rails.version >= "4.2.0"
def select_raw(arel, name = nil, binds = [], &block)
arel, binds = binds_from_relation arel, binds
sql = to_sql(arel, binds)
execute_and_clear(sql, name, binds, &block)
end
else
def select_raw(arel, name = nil, binds = [], &block)
arel, binds = binds_from_relation arel, binds
sql = to_sql(arel, binds)
result = without_prepared_statement?(binds) ? exec_no_cache(sql, 'SQL', binds) :
exec_cache(sql, 'SQL', binds)
yield result, nil
end
end
end
def pluck(*cols)
conn = ActiveRecord::Base.connection
relation = self
cols.map! do |column_name|
if column_name.is_a?(Symbol) && attribute_alias?(column_name)
attribute_alias(column_name)
else
column_name.to_s
end
end
if has_include?(cols.first)
construct_relation_for_association_calculations.pluck(*cols)
else
relation = spawn
relation.select_values = cols.map { |cn|
columns_hash.key?(cn) ? arel_table[cn] : cn
}
conn.select_raw(relation) do |result,_|
result.type_map = SqlBuilder.pg_type_map
result.nfields == 1 ? result.column_values(0) : result.values
end
end
end
end
# require 'benchmark/ips'
#
# ENV['RAILS_ENV'] = 'production'
# require File.expand_path("../../config/environment", __FILE__)
#
# Benchmark.ips do |x|
# x.report("fast_pluck") do
# Post.where(topic_id: 48464).fast_pluck(:id)
# end
#
# x.report("pluck") do
# Post.where(topic_id: 48464).pluck(:id)
# end
# end
#
# % ruby tmp/fast_pluck.rb
# Calculating -------------------------------------
# fast_pluck 165.000 i/100ms
# pluck 80.000 i/100ms
# -------------------------------------------------
# fast_pluck 1.720k (± 8.8%) i/s - 8.580k
# pluck 807.913 (± 4.0%) i/s - 4.080k
#

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@ -36,9 +36,9 @@ class SqlBuilder
when :where, :where2
joined = "WHERE " << v.map{|c| "(" << c << ")" }.join(" AND ")
when :join
joined = v.map{|v| "JOIN " << v }.join("\n")
joined = v.map{|item| "JOIN " << item }.join("\n")
when :left_join
joined = v.map{|v| "LEFT JOIN " << v }.join("\n")
joined = v.map{|item| "LEFT JOIN " << item }.join("\n")
when :limit
joined = "LIMIT " << v.last.to_s
when :offset
@ -69,46 +69,50 @@ class SqlBuilder
end
end
#AS reloads this on tests
remove_const :FTYPE_MAP if defined? FTYPE_MAP
if Rails.version >= "4.2.0"
FTYPE_MAP = {
23 => ActiveRecord::Type::Integer.new,
1114 => ActiveRecord::Type::DateTime.new,
16 => ActiveRecord::Type::Boolean.new
}
else
FTYPE_MAP = {
23 => :value_to_integer,
1114 => :string_to_time,
16 => :value_to_boolean
}
end
def self.map_exec(klass, sql, args = {})
self.new(sql).map_exec(klass, args)
end
class RailsDateTimeDecoder < PG::SimpleDecoder
def decode(string, tuple=nil, field=nil)
if Rails.version >= "4.2.0"
@caster ||= ActiveRecord::Type::DateTime.new
@caster.type_cast_from_database(string)
else
ActiveRecord::ConnectionAdapters::Column.string_to_time string
end
end
end
class ActiveRecordTypeMap < PG::BasicTypeMapForResults
def initialize(connection)
super(connection)
rm_coder 0, 1114
add_coder RailsDateTimeDecoder.new(name: "timestamp", oid: 1114, format: 0)
# we don't need deprecations
self.default_type_map = PG::TypeMapInRuby.new
end
end
def self.pg_type_map
conn = ActiveRecord::Base.connection.raw_connection
@typemap ||= ActiveRecordTypeMap.new(conn)
end
def map_exec(klass = OpenStruct, args = {})
results = exec(args)
results.type_map = SqlBuilder.pg_type_map
setters = results.fields.each_with_index.map do |f, index|
[(f.dup << "=").to_sym, FTYPE_MAP[results.ftype(index)]]
f.dup << "="
end
values = results.values
values.map! do |row|
mapped = klass.new
setters.each_with_index do |mapper, index|
translated = row[index]
if mapper[1] && !translated.nil?
if Rails.version >= "4.2.0"
translated = mapper[1].type_cast_from_database(translated)
else
translated = ActiveRecord::ConnectionAdapters::Column.send mapper[1], translated
end
end
mapped.send mapper[0], translated
setters.each_with_index do |name, index|
mapped.send name, row[index]
end
mapped
end

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@ -137,7 +137,6 @@ class TopicQuery
pinned_ids = query.where('pinned_at IS NOT NULL AND category_id = ?', category.id)
.order('pinned_at DESC').pluck(:id)
non_pinned_ids = query.where('pinned_at IS NULL OR category_id <> ?', category.id).pluck(:id)
(pinned_ids + non_pinned_ids)[0...@options[:per_page]]
end

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@ -2,9 +2,6 @@ require 'spec_helper'
require_dependency 'post_destroyer'
describe PostAction do
it { is_expected.to belong_to :user }
it { is_expected.to belong_to :post }
it { is_expected.to belong_to :post_action_type }
it { is_expected.to rate_limit }
let(:moderator) { Fabricate(:moderator) }
@ -458,6 +455,7 @@ describe PostAction do
end
expect(topic.reload.closed).to eq(true)
end
end