module ActiveRecord::ConnectionAdapters::QueryCache
Attributes
query_cache[R]
query_cache_enabled[R]
Public Class Methods
dirties_query_cache(base, *method_names)
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# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 9 def dirties_query_cache(base, *method_names) method_names.each do |method_name| base.class_eval " def #{method_name}(*) clear_query_cache if @query_cache_enabled super end ", __FILE__, __LINE__ + 1 end end
new(*)
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Calls superclass method
# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 23 def initialize(*) super @query_cache = Hash.new { |h,sql| h[sql] = {} } @query_cache_enabled = false end
Public Instance Methods
cache() { || ... }
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Enable the query cache within the block.
# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 30 def cache old, @query_cache_enabled = @query_cache_enabled, true yield ensure @query_cache_enabled = old clear_query_cache unless @query_cache_enabled end
clear_query_cache()
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Clears the query cache.
One reason you may wish to call this method explicitly is between queries that ask the database to randomize results. Otherwise the cache would see the same SQL query and repeatedly return the same result each time, silently undermining the randomness you were expecting.
# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 60 def clear_query_cache @query_cache.clear end
disable_query_cache!()
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# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 42 def disable_query_cache! @query_cache_enabled = false end
enable_query_cache!()
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# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 38 def enable_query_cache! @query_cache_enabled = true end
select_all(arel, name = nil, binds = [])
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Calls superclass method
# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 64 def select_all(arel, name = nil, binds = []) if @query_cache_enabled && !locked?(arel) arel, binds = binds_from_relation arel, binds sql = to_sql(arel, binds) cache_sql(sql, binds) { super(sql, name, binds) } else super end end
uncached() { || ... }
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Disable the query cache within the block.
# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 47 def uncached old, @query_cache_enabled = @query_cache_enabled, false yield ensure @query_cache_enabled = old end
Private Instance Methods
cache_sql(sql, binds) { || ... }
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# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 76 def cache_sql(sql, binds) result = if @query_cache[sql].key?(binds) ActiveSupport::Notifications.instrument("sql.active_record", :sql => sql, :binds => binds, :name => "CACHE", :connection_id => object_id) @query_cache[sql][binds] else @query_cache[sql][binds] = yield end result.dup end
locked?(arel)
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If arel is locked this is a SELECT … FOR UPDATE or somesuch. Such queries should not be cached.
# File lib/active_record/connection_adapters/abstract/query_cache.rb, line 90 def locked?(arel) arel.respond_to?(:locked) && arel.locked end