Use `table_exists?` from the schema cache.

activerecord/lib/active_record/base.rb

@@ -762,7 +762,7 @@ def set_sequence_name(value = nil, &block) #:nodoc:
 
       # Indicates whether the table associated with this class exists
       def table_exists?
-        connection.table_exists?(table_name)
+        connection.schema_cache.table_exists?(table_name)
       end
 
       # Returns an array of column objects for the table associated with this class.

activerecord/lib/active_record/connection_adapters/schema_cache.rb

@@ -42,10 +42,7 @@ def initialize(conn)
       def table_exists?(name)
         return @tables[name] if @tables.key? name
 
-        connection.tables.each { |table| @tables[table] = true }
-        @tables[name] = connection.table_exists?(name) if !@tables.key?(name)
-
-        @tables[name]
+        @tables[name] = connection.table_exists?(name)
       end
 
       # Clears out internal caches:
@@ -66,6 +63,7 @@ def clear_table_cache!(table_name)
         @columns_hash.delete table_name
         @column_defaults.delete table_name
         @primary_keys.delete table_name
+        @tables.delete table_name
       end
     end
   end

activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb

@@ -825,12 +825,12 @@ def test_caching_of_columns
     # clear cache possibly created by other tests
     david.projects.reset_column_information
 
-    # One query for columns, one for primary key
-    assert_queries(2) { david.projects.columns; david.projects.columns }
+    # One query for columns, one for primary key, one for table existence
+    assert_queries(3) { david.projects.columns; david.projects.columns }
 
     ## and again to verify that reset_column_information clears the cache correctly
     david.projects.reset_column_information
-    assert_queries(2) { david.projects.columns; david.projects.columns }
+    assert_queries(3) { david.projects.columns; david.projects.columns }
   end
 
   def test_attributes_are_being_set_when_initialized_from_habm_association_with_where_clause

activerecord/test/cases/session_store/session_test.rb

@@ -9,6 +9,7 @@ class SessionTest < ActiveRecord::TestCase
 
       def setup
         super
+        ActiveRecord::Base.connection.schema_cache.clear!
         Session.drop_table! if Session.table_exists?
       end