1 files changed, 23 insertions, 25 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 36c9815547..bc04565434 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -215,7 +215,7 @@ module ActiveRecord
 
         # @local_tz is initialized as nil to avoid warnings when connect tries to use it
         @local_tz = nil
-        @table_alias_length = nil
+        @max_identifier_length = nil
 
         connect
         add_pg_encoders
@@ -236,7 +236,9 @@ module ActiveRecord
 
       # Clears the prepared statements cache.
       def clear_cache!
-        @statements.clear
+        @lock.synchronize do
+          @statements.clear
+        end
       end
 
       def truncate(table_name, name = nil)
@@ -279,11 +281,6 @@ module ActiveRecord
         NATIVE_DATABASE_TYPES
       end
 
-      # Returns true, since this connection adapter supports migrations.
-      def supports_migrations?
-        true
-      end
-
       def set_standard_conforming_strings
         execute("SET standard_conforming_strings = on", "SCHEMA")
       end
@@ -361,8 +358,9 @@ module ActiveRecord
 
       # Returns the configured supported identifier length supported by PostgreSQL
       def table_alias_length
-        @table_alias_length ||= query("SHOW max_identifier_length", "SCHEMA")[0][0].to_i
+        @max_identifier_length ||= select_value("SHOW max_identifier_length", "SCHEMA").to_i
       end
+      alias index_name_length table_alias_length
 
       # Set the authorized user for this session
       def session_auth=(user)
@@ -374,10 +372,6 @@ module ActiveRecord
         @use_insert_returning
       end
 
-      def valid_type?(type)
-        !native_database_types[type].nil?
-      end
-
       def update_table_definition(table_name, base) #:nodoc:
         PostgreSQL::Table.new(table_name, base)
       end
@@ -637,8 +631,10 @@ module ActiveRecord
           if in_transaction?
             raise ActiveRecord::PreparedStatementCacheExpired.new(e.cause.message)
           else
-            # outside of transactions we can simply flush this query and retry
-            @statements.delete sql_key(sql)
+            @lock.synchronize do
+              # outside of transactions we can simply flush this query and retry
+              @statements.delete sql_key(sql)
+            end
             retry
           end
         end
@@ -674,19 +670,21 @@ module ActiveRecord
         # Prepare the statement if it hasn't been prepared, return
         # the statement key.
         def prepare_statement(sql)
-          sql_key = sql_key(sql)
-          unless @statements.key? sql_key
-            nextkey = @statements.next_key
-            begin
-              @connection.prepare nextkey, sql
-            rescue => e
-              raise translate_exception_class(e, sql)
+          @lock.synchronize do
+            sql_key = sql_key(sql)
+            unless @statements.key? sql_key
+              nextkey = @statements.next_key
+              begin
+                @connection.prepare nextkey, sql
+              rescue => e
+                raise translate_exception_class(e, sql)
+              end
+              # Clear the queue
+              @connection.get_last_result
+              @statements[sql_key] = nextkey
             end
-            # Clear the queue
-            @connection.get_last_result
-            @statements[sql_key] = nextkey
+            @statements[sql_key]
           end
-          @statements[sql_key]
         end
 
         # Connects to a PostgreSQL server and sets up the adapter depending on the