diff options
Diffstat (limited to 'activerecord/lib/active_record/relation')
3 files changed, 55 insertions, 6 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index 8f16de3519..402b317d9c 100644 --- a/activerecord/lib/active_record/relation/calculations.rb +++ b/activerecord/lib/active_record/relation/calculations.rb @@ -130,9 +130,9 @@ module ActiveRecord # the plucked column names, if they can be deduced. Plucking an SQL fragment # returns String values by default. # - # Person.pluck(:id) - # # SELECT people.id FROM people - # # => [1, 2, 3] + # Person.pluck(:name) + # # SELECT people.name FROM people + # # => ['David', 'Jeremy', 'Jose'] # # Person.pluck(:id, :name) # # SELECT people.id, people.name FROM people @@ -150,6 +150,8 @@ module ActiveRecord # # SELECT DATEDIFF(updated_at, created_at) FROM people # # => ['0', '27761', '173'] # + # See also +ids+. + # def pluck(*column_names) column_names.map! do |column_name| if column_name.is_a?(Symbol) && attribute_alias?(column_name) diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb index 3f747a20b3..6a3a56f1cc 100644 --- a/activerecord/lib/active_record/relation/finder_methods.rb +++ b/activerecord/lib/active_record/relation/finder_methods.rb @@ -5,7 +5,7 @@ module ActiveRecord ONE_AS_ONE = '1 AS one' # Find by id - This can either be a specific id (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]). - # If no record can be found for all of the listed ids, then RecordNotFound will be raised. If the primary key + # If one or more records can not be found for the requested ids, then RecordNotFound will be raised. If the primary key # is an integer, find by id coerces its arguments using +to_i+. # # Person.find(1) # returns the object for ID = 1 @@ -16,8 +16,6 @@ module ActiveRecord # Person.find([1]) # returns an array for the object with ID = 1 # Person.where("administrator = 1").order("created_on DESC").find(1) # - # <tt>ActiveRecord::RecordNotFound</tt> will be raised if one or more ids are not found. - # # NOTE: The returned records may not be in the same order as the ids you # provide since database rows are unordered. You'd need to provide an explicit <tt>order</tt> # option if you want the results are sorted. diff --git a/activerecord/lib/active_record/relation/record_fetch_warning.rb b/activerecord/lib/active_record/relation/record_fetch_warning.rb new file mode 100644 index 0000000000..14e1bf89fa --- /dev/null +++ b/activerecord/lib/active_record/relation/record_fetch_warning.rb @@ -0,0 +1,49 @@ +module ActiveRecord + class Relation + module RecordFetchWarning + # When this module is prepended to ActiveRecord::Relation and + # `config.active_record.warn_on_records_fetched_greater_than` is + # set to an integer, if the number of records a query returns is + # greater than the value of `warn_on_records_fetched_greater_than`, + # a warning is logged. This allows for the detection of queries that + # return a large number of records, which could cause memory bloat. + # + # In most cases, fetching large number of records can be performed + # efficiently using the ActiveRecord::Batches methods. + # See active_record/lib/relation/batches.rb for more information. + def exec_queries + QueryRegistry.reset + + super.tap do + if logger && warn_on_records_fetched_greater_than + if @records.length > warn_on_records_fetched_greater_than + logger.warn "Query fetched #{@records.size} #{@klass} records: #{QueryRegistry.queries.join(";")}" + end + end + end + end + + ActiveSupport::Notifications.subscribe("sql.active_record") do |*args| + payload = args.last + + QueryRegistry.queries << payload[:sql] + end + + class QueryRegistry # :nodoc: + extend ActiveSupport::PerThreadRegistry + + attr_accessor :queries + + def initialize + reset + end + + def reset + @queries = [] + end + end + end + end +end + +ActiveRecord::Relation.prepend ActiveRecord::Relation::RecordFetchWarning |