diff options
Diffstat (limited to 'activerecord/lib/active_record')
6 files changed, 48 insertions, 4 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb index 202187a047..7aad306d50 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb @@ -384,6 +384,11 @@ module ActiveRecord false end + # Does this adapter support optimizer hints? + def supports_optimizer_hints? + false + end + def supports_lazy_transactions? false end diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb index a518b897a0..6eefda763f 100644 --- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb +++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb @@ -103,6 +103,11 @@ module ActiveRecord mariadb? || version >= "5.7.5" end + # See https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html for more details. + def supports_optimizer_hints? + !mariadb? && version >= "5.7.7" + end + def supports_advisory_locks? true end diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb index 672f11cfcb..2905660499 100644 --- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb +++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb @@ -351,6 +351,13 @@ module ActiveRecord postgresql_version >= 90400 end + def supports_optimizer_hints? + unless defined?(@has_pg_hint_plan) + @has_pg_hint_plan = extension_available?("pg_hint_plan") + end + @has_pg_hint_plan + end + def supports_lazy_transactions? true end @@ -381,9 +388,12 @@ module ActiveRecord } end + def extension_available?(name) + query_value("SELECT true FROM pg_available_extensions WHERE name = #{quote(name)}", "SCHEMA") + end + def extension_enabled?(name) - res = exec_query("SELECT EXISTS(SELECT * FROM pg_available_extensions WHERE name = '#{name}' AND installed_version IS NOT NULL) as enabled", "SCHEMA") - res.cast_values.first + query_value("SELECT installed_version IS NOT NULL FROM pg_available_extensions WHERE name = #{quote(name)}", "SCHEMA") end def extensions diff --git a/activerecord/lib/active_record/querying.rb b/activerecord/lib/active_record/querying.rb index 7a8d0cb663..86021f0a80 100644 --- a/activerecord/lib/active_record/querying.rb +++ b/activerecord/lib/active_record/querying.rb @@ -14,7 +14,7 @@ module ActiveRecord :find_each, :find_in_batches, :in_batches, :select, :reselect, :order, :reorder, :group, :limit, :offset, :joins, :left_joins, :left_outer_joins, :where, :rewhere, :preload, :eager_load, :includes, :from, :lock, :readonly, :extending, :or, - :having, :create_with, :distinct, :references, :none, :unscope, :merge, :except, :only, + :having, :create_with, :distinct, :references, :none, :unscope, :optimizer_hints, :merge, :except, :only, :count, :average, :minimum, :maximum, :sum, :calculate, :pluck, :pick, :ids ].freeze # :nodoc: diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb index ac37f73b76..37179774fa 100644 --- a/activerecord/lib/active_record/relation.rb +++ b/activerecord/lib/active_record/relation.rb @@ -5,7 +5,7 @@ module ActiveRecord class Relation MULTI_VALUE_METHODS = [:includes, :eager_load, :preload, :select, :group, :order, :joins, :left_outer_joins, :references, - :extending, :unscope] + :extending, :unscope, :optimizer_hints] SINGLE_VALUE_METHODS = [:limit, :offset, :lock, :readonly, :reordering, :reverse_order, :distinct, :create_with, :skip_query_cache] diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb index 0f2cff4c9c..2603fac8b2 100644 --- a/activerecord/lib/active_record/relation/query_methods.rb +++ b/activerecord/lib/active_record/relation/query_methods.rb @@ -901,6 +901,29 @@ module ActiveRecord self end + # Specify optimizer hints to be used in the SELECT statement. + # + # Example (for MySQL): + # + # Topic.optimizer_hints("MAX_EXECUTION_TIME(50000)", "NO_INDEX_MERGE(topics)") + # # SELECT /*+ MAX_EXECUTION_TIME(50000) NO_INDEX_MERGE(topics) */ `topics`.* FROM `topics` + # + # Example (for PostgreSQL with pg_hint_plan): + # + # Topic.optimizer_hints("SeqScan(topics)", "Parallel(topics 8)") + # # SELECT /*+ SeqScan(topics) Parallel(topics 8) */ "topics".* FROM "topics" + def optimizer_hints(*args) + check_if_method_has_arguments!(:optimizer_hints, args) + spawn.optimizer_hints!(*args) + end + + def optimizer_hints!(*args) # :nodoc: + args.flatten! + + self.optimizer_hints_values += args + self + end + # Reverse the existing order clause on the relation. # # User.order('name ASC').reverse_order # generated SQL has 'ORDER BY name DESC' @@ -977,6 +1000,7 @@ module ActiveRecord build_select(arel) + arel.optimizer_hints(*optimizer_hints_values) unless optimizer_hints_values.empty? arel.distinct(distinct_value) arel.from(build_from) unless from_clause.empty? arel.lock(lock_value) if lock_value |