make add_index and remove_index more resilient; new rename_index method; track database limits

[#3452 state:committed]
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>

activerecord/lib/active_record/connection_adapters/abstract/database_limits.rb

+module ActiveRecord
+  module ConnectionAdapters # :nodoc:
+    module DatabaseLimits
+
+      # the maximum length of a table alias
+      def table_alias_length
+        255
+      end
+
+      # the maximum length of a column name
+      def column_name_length
+        64
+      end
+
+      # the maximum length of a table name
+      def table_name_length
+        64
+      end
+
+      # the maximum length of an index name
+      def index_name_length
+        64
+      end
+
+      # the maximum number of columns per table
+      def columns_per_table
+        1024
+      end
+
+      # the maximum number of indexes per table
+      def indexes_per_table
+        16
+      end
+
+      # the maximum number of columns in a multicolumn index
+      def columns_per_multicolumn_index
+        16
+      end
+
+      # the maximum number of elements in an IN (x,y,z) clause
+      def in_clause_length
+        65535
+      end
+
+      # the maximum length of a SQL query
+      def sql_query_length
+        1048575
+      end
+
+      # maximum number of joins in a single query
+      def joins_per_query
+        256
+      end
+
+    end
+  end
+end

activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

@@ -8,11 +8,6 @@ def native_database_types
         {}
       end
 
-      # This is the maximum length a table alias can be
-      def table_alias_length
-        255
-      end
-
       # Truncates a table alias according to the limits of the current adapter.
       def table_alias_for(table_name)
         table_name[0..table_alias_length-1].gsub(/\./, '_')
@@ -283,6 +278,14 @@ def add_index(table_name, column_name, options = {})
           index_type = options
         end
 
+        if index_name.length > index_name_length
+          @logger.warn("Index name '#{index_name}' on table '#{table_name}' is too long; the limit is #{index_name_length} characters. Skipping.")
+          return
+        end
+        if index_exists?(table_name, index_name, false)
+          @logger.warn("Index name '#{index_name}' on table '#{table_name}' already exists. Skipping.")
+          return
+        end
         quoted_column_names = quoted_columns_for_index(column_names, options).join(", ")
 
         execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} (#{quoted_column_names})"
@@ -299,7 +302,28 @@ def add_index(table_name, column_name, options = {})
       # Remove the index named by_branch_party in the accounts table.
       #   remove_index :accounts, :name => :by_branch_party
       def remove_index(table_name, options = {})
-        execute "DROP INDEX #{quote_column_name(index_name(table_name, options))} ON #{quote_table_name(table_name)}"
+        index_name = index_name(table_name, options)
+        unless index_exists?(table_name, index_name, true)
+          @logger.warn("Index name '#{index_name}' on table '#{table_name}' does not exist. Skipping.")
+          return
+        end
+        remove_index!(table_name, index_name)
+      end
+
+      def remove_index!(table_name, index_name) #:nodoc:
+        execute "DROP INDEX #{quote_column_name(index_name)} ON #{table_name}"
+      end
+
+      # Rename an index.
+      #
+      # Rename the index_people_on_last_name index to index_users_on_last_name
+      #   rename_index :people, 'index_people_on_last_name', 'index_users_on_last_name'
+      def rename_index(table_name, old_name, new_name)
+        # this is a naive implementation; some DBs may support this more efficiently (Postgres, for instance)
+        old_index_def = indexes(table_name).detect { |i| i.name == old_name }
+        return unless old_index_def
+        remove_index(table_name, :name => old_name)
+        add_index(table_name, old_index_def.columns, :name => new_name, :unique => old_index_def.unique)
       end
 
       def index_name(table_name, options) #:nodoc:
@@ -316,6 +340,15 @@ def index_name(table_name, options) #:nodoc:
         end
       end
 
+      # Verify the existence of an index.
+      #
+      # The default argument is returned if the underlying implementation does not define the indexes method,
+      # as there's no way to determine the correct answer in that case.
+      def index_exists?(table_name, index_name, default)
+        return default unless respond_to?(:indexes)
+        indexes(table_name).detect { |i| i.name == index_name }
+      end
+
       # Returns a string of <tt>CREATE TABLE</tt> SQL statement(s) for recreating the
       # entire structure of the database.
       def structure_dump

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -11,6 +11,7 @@
 require 'active_record/connection_adapters/abstract/connection_pool'
 require 'active_record/connection_adapters/abstract/connection_specification'
 require 'active_record/connection_adapters/abstract/query_cache'
+require 'active_record/connection_adapters/abstract/database_limits'
 
 module ActiveRecord
   module ConnectionAdapters # :nodoc:
@@ -29,6 +30,7 @@ module ConnectionAdapters # :nodoc:
     # notably, the instance methods provided by SchemaStatement are very useful.
     class AbstractAdapter
       include Quoting, DatabaseStatements, SchemaStatements
+      include DatabaseLimits
       include QueryCache
       include ActiveSupport::Callbacks
       define_callbacks :checkout, :checkin

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -859,9 +859,12 @@ def rename_column(table_name, column_name, new_column_name)
         execute "ALTER TABLE #{quote_table_name(table_name)} RENAME COLUMN #{quote_column_name(column_name)} TO #{quote_column_name(new_column_name)}"
       end
 
-      # Drops an index from a table.
-      def remove_index(table_name, options = {})
-        execute "DROP INDEX #{quote_table_name(index_name(table_name, options))}"
+      def remove_index!(table_name, index_name) #:nodoc:
+        execute "DROP INDEX #{quote_table_name(index_name)}"
+      end
+
+      def index_name_length
+        63
       end
 
       # Maps logical Rails types to PostgreSQL-specific data types.

activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb

@@ -244,8 +244,8 @@ def primary_key(table_name) #:nodoc:
         column ? column['name'] : nil
       end
 
-      def remove_index(table_name, options={}) #:nodoc:
-        execute "DROP INDEX #{quote_column_name(index_name(table_name, options))}"
+      def remove_index!(table_name, index_name) #:nodoc:
+        execute "DROP INDEX #{quote_column_name(index_name)}"
       end
 
       def rename_table(name, new_name)

activerecord/test/cases/active_schema_test_mysql.rb

@@ -16,6 +16,10 @@ def teardown
   end
 
   def test_add_index
+    # add_index calls index_exists? which can't work since execute is stubbed
+    ActiveRecord::ConnectionAdapters::MysqlAdapter.send(:define_method, :index_exists?) do |*|
+      false
+    end
     expected = "CREATE  INDEX `index_people_on_last_name` ON `people` (`last_name`)"
     assert_equal expected, add_index(:people, :last_name, :length => nil)
 
@@ -30,6 +34,7 @@ def test_add_index
 
     expected = "CREATE  INDEX `index_people_on_last_name_and_first_name` ON `people` (`last_name`(15), `first_name`(10))"
     assert_equal expected, add_index(:people, [:last_name, :first_name], :length => {:last_name => 15, :first_name => 10})
+    ActiveRecord::ConnectionAdapters::MysqlAdapter.send(:remove_method, :index_exists?)
   end
 
   def test_drop_table

activerecord/test/cases/migration_test.rb

@@ -119,6 +119,40 @@ def test_add_index
       end
     end
 
+    def test_add_index_length_limit
+      good_index_name = 'x' * Person.connection.index_name_length
+      too_long_index_name = good_index_name + 'x'
+      assert_nothing_raised { Person.connection.add_index("people", "first_name", :name => too_long_index_name) }
+      assert !Person.connection.index_exists?("people", too_long_index_name, false)
+      assert_nothing_raised { Person.connection.add_index("people", "first_name", :name => good_index_name) }
+      assert Person.connection.index_exists?("people", good_index_name, false)
+    end
+
+    def test_remove_nonexistent_index
+      # we do this by name, so OpenBase is a wash as noted above
+      unless current_adapter?(:OpenBaseAdapter)
+        assert_nothing_raised { Person.connection.remove_index("people", "no_such_index") }
+      end
+    end
+
+    def test_rename_index
+      unless current_adapter?(:OpenBaseAdapter)
+        # keep the names short to make Oracle and similar behave
+        Person.connection.add_index('people', [:first_name], :name => 'old_idx')
+        assert_nothing_raised { Person.connection.rename_index('people', 'old_idx', 'new_idx') }
+        # if the adapter doesn't support the indexes call, pick defaults that let the test pass
+        assert !Person.connection.index_exists?('people', 'old_idx', false)
+        assert Person.connection.index_exists?('people', 'new_idx', true)
+      end
+    end
+
+    def test_double_add_index
+      unless current_adapter?(:OpenBaseAdapter)
+        Person.connection.add_index('people', [:first_name], :name => 'some_idx')
+        assert_nothing_raised { Person.connection.add_index('people', [:first_name], :name => 'some_idx') }
+      end
+    end
+
     def testing_table_with_only_foo_attribute
       Person.connection.create_table :testings, :id => false do |t|
         t.column :foo, :string

activerecord/test/cases/schema_test_postgresql.rb

@@ -137,11 +137,11 @@ def test_dump_indexes_for_schema_two
 
   def test_with_uppercase_index_name
     ActiveRecord::Base.connection.execute "CREATE INDEX \"things_Index\" ON #{SCHEMA_NAME}.things (name)"
-    assert_nothing_raised { ActiveRecord::Base.connection.remove_index :things, :name => "#{SCHEMA_NAME}.things_Index"}
+    assert_nothing_raised { ActiveRecord::Base.connection.remove_index! "things", "#{SCHEMA_NAME}.things_Index"}
 
     ActiveRecord::Base.connection.execute "CREATE INDEX \"things_Index\" ON #{SCHEMA_NAME}.things (name)"
     ActiveRecord::Base.connection.schema_search_path = SCHEMA_NAME
-    assert_nothing_raised { ActiveRecord::Base.connection.remove_index :things, :name => "things_Index"}
+    assert_nothing_raised { ActiveRecord::Base.connection.remove_index! "things", "things_Index"}
     ActiveRecord::Base.connection.schema_search_path = "public"
   end