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remove AR auto-explain (config.auto_explain_threshold_in_seconds)

We discussed that the auto explain feature is rarely used.
This PR removes only the automatic explain. You can still display
the explain output for any given relation using `ActiveRecord::Relation#explain`.

As a side-effect this should also fix the connection problem during
asset compilation (#9385). The auto explain initializer in the `ActiveRecord::Railtie`
forced a connection.
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1 parent 5fc3b87 commit d3688e02ca52c0b72d3092e8498da51e06b7fc58 @senny senny committed Feb 24, 2013
@@ -1,5 +1,14 @@
## Rails 4.0.0 (unreleased) ##
+* The auto explain feature has been removed. This feature was
+ activated by configuring `config.active_record.auto_explain_threshold_in_seconds`.
+ The configuration option was deprecated and has no more effect.
+
+ You can still use `ActiveRecord::Relation#explain` to see the EXPLAIN output for
+ any given relation.
+
+ *Yves Senn*
+
* The `:on` option for `after_commit` and `after_rollback` now
accepts an Array of actions.
Fixes #988.
@@ -2,43 +2,7 @@
module ActiveRecord
module Explain
- def self.extended(base)
- base.mattr_accessor :auto_explain_threshold_in_seconds, instance_accessor: false
- end
-
- # If the database adapter supports explain and auto explain is enabled,
- # this method triggers EXPLAIN logging for the queries triggered by the
- # block if it takes more than the threshold as a whole. That is, the
- # threshold is not checked against each individual query, but against the
- # duration of the entire block. This approach is convenient for relations.
-
- #
- # The available_queries_for_explain thread variable collects the queries
- # to be explained. If the value is nil, it means queries are not being
- # currently collected. A false value indicates collecting is turned
- # off. Otherwise it is an array of queries.
- def logging_query_plan # :nodoc:
- return yield unless logger
-
- threshold = auto_explain_threshold_in_seconds
- current = Thread.current
- if connection.supports_explain? && threshold && current[:available_queries_for_explain].nil?
- begin
- queries = current[:available_queries_for_explain] = []
- start = Time.now
- result = yield
- logger.warn(exec_explain(queries)) if Time.now - start > threshold
- result
- ensure
- current[:available_queries_for_explain] = nil
- end
- else
- yield
- end
- end
-
- # Relation#explain needs to be able to collect the queries regardless of
- # whether auto explain is enabled. This method serves that purpose.
+ # Relation#explain needs to be able to collect the queries.
def collecting_queries_for_explain # :nodoc:
current = Thread.current
original, current[:available_queries_for_explain] = current[:available_queries_for_explain], []
@@ -68,20 +32,5 @@ def str.inspect
end
str
end
-
- # Silences automatic EXPLAIN logging for the duration of the block.
- #
- # This has high priority, no EXPLAINs will be run even if downwards
- # the threshold is set to 0.
- #
- # As the name of the method suggests this only applies to automatic
- # EXPLAINs, manual calls to <tt>ActiveRecord::Relation#explain</tt> run.
- def silence_auto_explain
- current = Thread.current
- original, current[:available_queries_for_explain] = current[:available_queries_for_explain], false
- yield
- ensure
- current[:available_queries_for_explain] = original
- end
end
end
@@ -33,18 +33,16 @@ module Querying
# Post.find_by_sql ["SELECT title FROM posts WHERE author = ? AND created > ?", author_id, start_date]
# # => [#<Post:0x36bff9c @attributes={"title"=>"The Cheap Man Buys Twice"}>, ...]
def find_by_sql(sql, binds = [])
- logging_query_plan do
- result_set = connection.select_all(sanitize_sql(sql), "#{name} Load", binds)
- column_types = {}
+ result_set = connection.select_all(sanitize_sql(sql), "#{name} Load", binds)
+ column_types = {}
- if result_set.respond_to? :column_types
- column_types = result_set.column_types
- else
- ActiveSupport::Deprecation.warn "the object returned from `select_all` must respond to `column_types`"
- end
-
- result_set.map { |record| instantiate(record, column_types) }
+ if result_set.respond_to? :column_types
+ column_types = result_set.column_types
+ else
+ ActiveSupport::Deprecation.warn "the object returned from `select_all` must respond to `column_types`"
end
+
+ result_set.map { |record| instantiate(record, column_types) }
end
# Returns the result of an SQL statement that should only include a COUNT(*) in the SELECT part.
@@ -57,10 +55,8 @@ def find_by_sql(sql, binds = [])
#
# Product.count_by_sql "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"
def count_by_sql(sql)
- logging_query_plan do
- sql = sanitize_conditions(sql)
- connection.select_value(sql, "#{name} Count").to_i
- end
+ sql = sanitize_conditions(sql)
+ connection.select_value(sql, "#{name} Count").to_i
end
end
end
@@ -112,7 +112,18 @@ class Railtie < Rails::Railtie # :nodoc:
`config/application.rb` file and any `mass_assignment_sanitizer` options
from your `config/environments/*.rb` files.
- See http://guides.rubyonrails.org/security.html#mass-assignment for more information
+ See http://guides.rubyonrails.org/security.html#mass-assignment for more information.
+ EOF
+ end
+
+ unless app.config.active_record.delete(:auto_explain_threshold_in_seconds).nil?
+ ActiveSupport::Deprecation.warn <<-EOF.strip_heredoc, []
+ The Active Record auto explain feature has been removed.
+
+ To disable this message remove the `active_record.auto_explain_threshold_in_seconds`
+ option from the `config/environments/*.rb` config file.
+
+ See http://guides.rubyonrails.org/4_0_release_notes.html for more information.
EOF
end
@@ -124,7 +135,7 @@ class Railtie < Rails::Railtie # :nodoc:
To disable this message remove the `observers` option from your
`config/application.rb` or from your initializers.
- See http://guides.rubyonrails.org/4_0_release_notes.html for more information
+ See http://guides.rubyonrails.org/4_0_release_notes.html for more information.
EOF
end
ensure
@@ -146,13 +157,6 @@ class Railtie < Rails::Railtie # :nodoc:
end
end
- initializer "active_record.validate_explain_support" do |app|
- if app.config.active_record[:auto_explain_threshold_in_seconds] &&
- !ActiveRecord::Base.connection.supports_explain?
- warn "auto_explain_threshold_in_seconds is set but will be ignored because your adapter does not support this feature. Please unset the configuration to avoid this warning."
- end
- end
-
# Expose database runtime to controller for logging.
initializer "active_record.log_runtime" do |app|
require "active_record/railties/controller_runtime"
@@ -444,17 +444,7 @@ def delete(id_or_array)
#
# Post.where(published: true).load # => #<ActiveRecord::Relation>
def load
- unless loaded?
- # We monitor here the entire execution rather than individual SELECTs
- # because from the point of view of the user fetching the records of a
- # relation is a single unit of work. You want to know if this call takes
- # too long, not if the individual queries take too long.
- #
- # It could be the case that none of the queries involved surpass the
- # threshold, and at the same time the sum of them all does. The user
- # should get a query plan logged in that case.
- logging_query_plan { exec_queries }
- end
+ exec_queries unless loaded?
self
end
@@ -12,7 +12,7 @@ module Delegation # :nodoc:
delegate :to_xml, :to_yaml, :length, :collect, :map, :each, :all?, :include?, :to_ary, :to => :to_a
delegate :table_name, :quoted_table_name, :primary_key, :quoted_primary_key,
- :connection, :columns_hash, :auto_explain_threshold_in_seconds, :to => :klass
+ :connection, :columns_hash, :to => :klass
module ClassSpecificRelation
extend ActiveSupport::Concern
@@ -14,46 +14,9 @@ def connection
base.connection
end
- def test_logging_query_plan_with_logger
- base.logger.expects(:warn).with do |message|
- message.starts_with?('EXPLAIN for:')
- end
-
- with_threshold(0) do
- Car.where(:name => 'honda').to_a
- end
- end
-
- def test_logging_query_plan_without_logger
- original = base.logger
- base.logger = nil
-
- class << base.logger
- def warn; raise "Should not be called" end
- end
-
- with_threshold(0) do
- car = Car.where(:name => 'honda').first
- assert_equal 'honda', car.name
- end
- ensure
- base.logger = original
- end
-
- def test_collect_queries_for_explain
- base.auto_explain_threshold_in_seconds = nil
- queries = Thread.current[:available_queries_for_explain] = []
-
- with_threshold(0) do
- Car.where(:name => 'honda').to_a
- end
-
- sql, binds = queries[0]
- assert_match "SELECT", sql
- assert_match "honda", sql
- assert_equal [], binds
- ensure
- Thread.current[:available_queries_for_explain] = nil
+ def test_relation_explain
+ message = Car.where(:name => 'honda').explain
+ assert_match(/^EXPLAIN for:/, message)
end
def test_collecting_queries_for_explain
@@ -68,16 +31,6 @@ def test_collecting_queries_for_explain
assert_equal [cars(:honda)], result
end
- def test_logging_query_plan_when_counting_by_sql
- base.logger.expects(:warn).with do |message|
- message.starts_with?('EXPLAIN for:')
- end
-
- with_threshold(0) do
- Car.count_by_sql "SELECT COUNT(*) FROM cars WHERE name = 'honda'"
- end
- end
-
def test_exec_explain_with_no_binds
sqls = %w(foo bar)
binds = [[], []]
@@ -113,25 +66,8 @@ def test_unsupported_connection_adapter
base.logger.expects(:warn).never
- with_threshold(0) do
- Car.where(:name => 'honda').to_a
- end
- end
-
- def test_silence_auto_explain
- base.expects(:collecting_sqls_for_explain).never
- base.logger.expects(:warn).never
- base.silence_auto_explain do
- with_threshold(0) { Car.all.to_a }
- end
+ Car.where(:name => 'honda').to_a
end
- def with_threshold(threshold)
- current_threshold = base.auto_explain_threshold_in_seconds
- base.auto_explain_threshold_in_seconds = threshold
- yield
- ensure
- base.auto_explain_threshold_in_seconds = current_threshold
- end
end
end
@@ -22,10 +22,6 @@
# Only use best-standards-support built into browsers.
config.action_dispatch.best_standards_support = :builtin
- # Log the query plan for queries taking more than this (works
- # with SQLite, MySQL, and PostgreSQL).
- config.active_record.auto_explain_threshold_in_seconds = 0.5
-
# Raise an error on page load if there are pending migrations
config.active_record.migration_error = :page_load
@@ -72,10 +72,6 @@
# Send deprecation notices to registered listeners.
config.active_support.deprecation = :notify
- # Log the query plan for queries taking more than this (works
- # with SQLite, MySQL, and PostgreSQL).
- # config.active_record.auto_explain_threshold_in_seconds = 0.5
-
# Disable automatic flushing of the log to improve performance.
# config.autoflush_log = false
@@ -1609,45 +1609,6 @@ EXPLAIN for: SELECT `posts`.* FROM `posts` WHERE `posts`.`user_id` IN (1)
under MySQL.
-### Automatic EXPLAIN
-
-Active Record is able to run EXPLAIN automatically on slow queries and log its
-output. This feature is controlled by the configuration parameter
-
-```ruby
-config.active_record.auto_explain_threshold_in_seconds
-```
-
-If set to a number, any query exceeding those many seconds will have its EXPLAIN
-automatically triggered and logged. In the case of relations, the threshold is
-compared to the total time needed to fetch records. So, a relation is seen as a
-unit of work, no matter whether the implementation of eager loading involves
-several queries under the hood.
-
-A threshold of `nil` disables automatic EXPLAINs.
-
-The default threshold in development mode is 0.5 seconds, and `nil` in test and
-production modes.
-
-INFO. Automatic EXPLAIN gets disabled if Active Record has no logger, regardless
-of the value of the threshold.
-
-#### Disabling Automatic EXPLAIN
-
-Automatic EXPLAIN can be selectively silenced with `ActiveRecord::Base.silence_auto_explain`:
-
-```ruby
-ActiveRecord::Base.silence_auto_explain do
- # no automatic EXPLAIN is triggered here
-end
-```
-
-That may be useful for queries you know are slow but fine, like a heavyweight
-report of an admin interface.
-
-As its name suggests, `silence_auto_explain` only silences automatic EXPLAINs.
-Explicit calls to `ActiveRecord::Relation#explain` run.
-
### Interpreting EXPLAIN
Interpretation of the output of EXPLAIN is beyond the scope of this guide. The
@@ -268,8 +268,6 @@ config.middleware.delete "Rack::MethodOverride"
* `config.active_record.lock_optimistically` controls whether Active Record will use optimistic locking and is true by default.
-* `config.active_record.auto_explain_threshold_in_seconds` configures the threshold for automatic EXPLAINs (`nil` disables this feature). Queries exceeding the threshold get their query plan logged. Default is 0.5 in development mode.
-
* +config.active_record.cache_timestamp_format+ controls the format of the timestamp value in the cache key. Default is +:number+.
The MySQL adapter adds one additional configuration option:
@@ -20,10 +20,6 @@
config.active_support.deprecation = :log
<%- unless options.skip_active_record? -%>
- # Log the query plan for queries taking more than this (works
- # with SQLite, MySQL, and PostgreSQL).
- config.active_record.auto_explain_threshold_in_seconds = 0.5
-
# Raise an error on page load if there are pending migrations
config.active_record.migration_error = :page_load
<%- end -%>
@@ -76,12 +76,6 @@
# Send deprecation notices to registered listeners.
config.active_support.deprecation = :notify
- <%- unless options.skip_active_record? -%>
- # Log the query plan for queries taking more than this (works
- # with SQLite, MySQL, and PostgreSQL).
- # config.active_record.auto_explain_threshold_in_seconds = 0.5
- <%- end -%>
-
# Disable automatic flushing of the log to improve performance.
# config.autoflush_log = false
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1 comment on commit d3688e0

Contributor

korny commented on d3688e0 Mar 3, 2013

this should also fix the connection problem during asset compilation

\o/

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