Merge remote-tracking branch 'upstream/master' into 27377-preload-pipeline-entity27377-preload-pipeline-entity

* upstream/master: (2534 commits)
  Update VERSION to 9.3.0-pre
  Update CHANGELOG.md for 9.2.0
  removes unnecessary redundacy in usage ping doc
  Respect the typo as rubocop said
  Add a test to ensure this works on MySQL
  Change pipelines schedules help page path
  change domain to hostname in usage ping doc
  Fixes broken MySQL migration for retried
  Show password field mask while editing service settings
  Add notes for supported schedulers and cloud providers
  Move environment monitoring to environments doc
  Add docs for change of Cache/Artifact restore order"
  Avoid resource intensive login checks if password is not provided
  Change translation for 'coding' by 'desarrollo' for Spanish
  Add to docs: issues multiple assignees
  rename "Add emoji" and "Award emoji" to "Add reaction" where appropriate
  Add project and group notification settings info
  32570 Fix border-bottom for project activity tab
  Add users endpoint to frontend API class
  Rename users on mysql
  ...

1 files changed, 301 insertions, 1 deletions

diff --git a/lib/gitlab/database/migration_helpers.rb b/lib/gitlab/database/migration_helpers.rb
index fc445ab9483..e76c9abbe04 100644
--- a/lib/gitlab/database/migration_helpers.rb
+++ b/lib/gitlab/database/migration_helpers.rb
@@ -26,6 +26,30 @@ module Gitlab
         add_index(table_name, column_name, options)
       end
 
+      # Removes an existed index, concurrently when supported
+      #
+      # On PostgreSQL this method removes an index concurrently.
+      #
+      # Example:
+      #
+      #     remove_concurrent_index :users, :some_column
+      #
+      # See Rails' `remove_index` for more info on the available arguments.
+      def remove_concurrent_index(table_name, column_name, options = {})
+        if transaction_open?
+          raise 'remove_concurrent_index can not be run inside a transaction, ' \
+            'you can disable transactions by calling disable_ddl_transaction! ' \
+            'in the body of your migration class'
+        end
+
+        if Database.postgresql?
+          options = options.merge({ algorithm: :concurrently })
+          disable_statement_timeout
+        end
+
+        remove_index(table_name, options.merge({ column: column_name }))
+      end
+
       # Adds a foreign key with only minimal locking on the tables involved.
       #
       # This method only requires minimal locking when using PostgreSQL. When
@@ -65,7 +89,8 @@ module Gitlab
         ADD CONSTRAINT #{key_name}
         FOREIGN KEY (#{column})
         REFERENCES #{target} (id)
-        ON DELETE #{on_delete} NOT VALID;
+        #{on_delete ? "ON DELETE #{on_delete}" : ''}
+        NOT VALID;
         EOF
 
         # Validate the existing constraint. This can potentially take a very
@@ -90,6 +115,14 @@ module Gitlab
         execute('SET statement_timeout TO 0') if Database.postgresql?
       end
 
+      def true_value
+        Database.true_value
+      end
+
+      def false_value
+        Database.false_value
+      end
+
       # Updates the value of a column in batches.
       #
       # This method updates the table in batches of 5% of the total row count.
@@ -226,6 +259,273 @@ module Gitlab
           raise error
         end
       end
+
+      # Renames a column without requiring downtime.
+      #
+      # Concurrent renames work by using database triggers to ensure both the
+      # old and new column are in sync. However, this method will _not_ remove
+      # the triggers or the old column automatically; this needs to be done
+      # manually in a post-deployment migration. This can be done using the
+      # method `cleanup_concurrent_column_rename`.
+      #
+      # table - The name of the database table containing the column.
+      # old - The old column name.
+      # new - The new column name.
+      # type - The type of the new column. If no type is given the old column's
+      #        type is used.
+      def rename_column_concurrently(table, old, new, type: nil)
+        if transaction_open?
+          raise 'rename_column_concurrently can not be run inside a transaction'
+        end
+
+        old_col = column_for(table, old)
+        new_type = type || old_col.type
+
+        add_column(table, new, new_type,
+                   limit: old_col.limit,
+                   precision: old_col.precision,
+                   scale: old_col.scale)
+
+        # We set the default value _after_ adding the column so we don't end up
+        # updating any existing data with the default value. This isn't
+        # necessary since we copy over old values further down.
+        change_column_default(table, new, old_col.default) if old_col.default
+
+        trigger_name = rename_trigger_name(table, old, new)
+        quoted_table = quote_table_name(table)
+        quoted_old = quote_column_name(old)
+        quoted_new = quote_column_name(new)
+
+        if Database.postgresql?
+          install_rename_triggers_for_postgresql(trigger_name, quoted_table,
+                                                 quoted_old, quoted_new)
+        else
+          install_rename_triggers_for_mysql(trigger_name, quoted_table,
+                                            quoted_old, quoted_new)
+        end
+
+        update_column_in_batches(table, new, Arel::Table.new(table)[old])
+
+        change_column_null(table, new, false) unless old_col.null
+
+        copy_indexes(table, old, new)
+        copy_foreign_keys(table, old, new)
+      end
+
+      # Changes the type of a column concurrently.
+      #
+      # table - The table containing the column.
+      # column - The name of the column to change.
+      # new_type - The new column type.
+      def change_column_type_concurrently(table, column, new_type)
+        temp_column = "#{column}_for_type_change"
+
+        rename_column_concurrently(table, column, temp_column, type: new_type)
+      end
+
+      # Performs cleanup of a concurrent type change.
+      #
+      # table - The table containing the column.
+      # column - The name of the column to change.
+      # new_type - The new column type.
+      def cleanup_concurrent_column_type_change(table, column)
+        temp_column = "#{column}_for_type_change"
+
+        transaction do
+          # This has to be performed in a transaction as otherwise we might have
+          # inconsistent data.
+          cleanup_concurrent_column_rename(table, column, temp_column)
+          rename_column(table, temp_column, column)
+        end
+      end
+
+      # Cleans up a concurrent column name.
+      #
+      # This method takes care of removing previously installed triggers as well
+      # as removing the old column.
+      #
+      # table - The name of the database table.
+      # old - The name of the old column.
+      # new - The name of the new column.
+      def cleanup_concurrent_column_rename(table, old, new)
+        trigger_name = rename_trigger_name(table, old, new)
+
+        if Database.postgresql?
+          remove_rename_triggers_for_postgresql(table, trigger_name)
+        else
+          remove_rename_triggers_for_mysql(trigger_name)
+        end
+
+        remove_column(table, old)
+      end
+
+      # Performs a concurrent column rename when using PostgreSQL.
+      def install_rename_triggers_for_postgresql(trigger, table, old, new)
+        execute <<-EOF.strip_heredoc
+        CREATE OR REPLACE FUNCTION #{trigger}()
+        RETURNS trigger AS
+        $BODY$
+        BEGIN
+          NEW.#{new} := NEW.#{old};
+          RETURN NEW;
+        END;
+        $BODY$
+        LANGUAGE 'plpgsql'
+        VOLATILE
+        EOF
+
+        execute <<-EOF.strip_heredoc
+        CREATE TRIGGER #{trigger}
+        BEFORE INSERT OR UPDATE
+        ON #{table}
+        FOR EACH ROW
+        EXECUTE PROCEDURE #{trigger}()
+        EOF
+      end
+
+      # Installs the triggers necessary to perform a concurrent column rename on
+      # MySQL.
+      def install_rename_triggers_for_mysql(trigger, table, old, new)
+        execute <<-EOF.strip_heredoc
+        CREATE TRIGGER #{trigger}_insert
+        BEFORE INSERT
+        ON #{table}
+        FOR EACH ROW
+        SET NEW.#{new} = NEW.#{old}
+        EOF
+
+        execute <<-EOF.strip_heredoc
+        CREATE TRIGGER #{trigger}_update
+        BEFORE UPDATE
+        ON #{table}
+        FOR EACH ROW
+        SET NEW.#{new} = NEW.#{old}
+        EOF
+      end
+
+      # Removes the triggers used for renaming a PostgreSQL column concurrently.
+      def remove_rename_triggers_for_postgresql(table, trigger)
+        execute("DROP TRIGGER #{trigger} ON #{table}")
+        execute("DROP FUNCTION #{trigger}()")
+      end
+
+      # Removes the triggers used for renaming a MySQL column concurrently.
+      def remove_rename_triggers_for_mysql(trigger)
+        execute("DROP TRIGGER #{trigger}_insert")
+        execute("DROP TRIGGER #{trigger}_update")
+      end
+
+      # Returns the (base) name to use for triggers when renaming columns.
+      def rename_trigger_name(table, old, new)
+        'trigger_' + Digest::SHA256.hexdigest("#{table}_#{old}_#{new}").first(12)
+      end
+
+      # Returns an Array containing the indexes for the given column
+      def indexes_for(table, column)
+        column = column.to_s
+
+        indexes(table).select { |index| index.columns.include?(column) }
+      end
+
+      # Returns an Array containing the foreign keys for the given column.
+      def foreign_keys_for(table, column)
+        column = column.to_s
+
+        foreign_keys(table).select { |fk| fk.column == column }
+      end
+
+      # Copies all indexes for the old column to a new column.
+      #
+      # table - The table containing the columns and indexes.
+      # old - The old column.
+      # new - The new column.
+      def copy_indexes(table, old, new)
+        old = old.to_s
+        new = new.to_s
+
+        indexes_for(table, old).each do |index|
+          new_columns = index.columns.map do |column|
+            column == old ? new : column
+          end
+
+          # This is necessary as we can't properly rename indexes such as
+          # "ci_taggings_idx".
+          unless index.name.include?(old)
+            raise "The index #{index.name} can not be copied as it does not "\
+              "mention the old column. You have to rename this index manually first."
+          end
+
+          name = index.name.gsub(old, new)
+
+          options = {
+            unique: index.unique,
+            name: name,
+            length: index.lengths,
+            order: index.orders
+          }
+
+          # These options are not supported by MySQL, so we only add them if
+          # they were previously set.
+          options[:using] = index.using if index.using
+          options[:where] = index.where if index.where
+
+          unless index.opclasses.blank?
+            opclasses = index.opclasses.dup
+
+            # Copy the operator classes for the old column (if any) to the new
+            # column.
+            opclasses[new] = opclasses.delete(old) if opclasses[old]
+
+            options[:opclasses] = opclasses
+          end
+
+          add_concurrent_index(table, new_columns, options)
+        end
+      end
+
+      # Copies all foreign keys for the old column to the new column.
+      #
+      # table - The table containing the columns and indexes.
+      # old - The old column.
+      # new - The new column.
+      def copy_foreign_keys(table, old, new)
+        foreign_keys_for(table, old).each do |fk|
+          add_concurrent_foreign_key(fk.from_table,
+                                     fk.to_table,
+                                     column: new,
+                                     on_delete: fk.on_delete)
+        end
+      end
+
+      # Returns the column for the given table and column name.
+      def column_for(table, name)
+        name = name.to_s
+
+        columns(table).find { |column| column.name == name }
+      end
+
+      # This will replace the first occurance of a string in a column with
+      # the replacement
+      # On postgresql we can use `regexp_replace` for that.
+      # On mysql we find the location of the pattern, and overwrite it
+      # with the replacement
+      def replace_sql(column, pattern, replacement)
+        quoted_pattern = Arel::Nodes::Quoted.new(pattern.to_s)
+        quoted_replacement = Arel::Nodes::Quoted.new(replacement.to_s)
+
+        if Database.mysql?
+          locate = Arel::Nodes::NamedFunction.
+            new('locate', [quoted_pattern, column])
+          insert_in_place = Arel::Nodes::NamedFunction.
+            new('insert', [column, locate, pattern.size, quoted_replacement])
+
+          Arel::Nodes::SqlLiteral.new(insert_in_place.to_sql)
+        else
+          replace = Arel::Nodes::NamedFunction.
+            new("regexp_replace", [column, quoted_pattern, quoted_replacement])
+          Arel::Nodes::SqlLiteral.new(replace.to_sql)
+        end
+      end
     end
   end
 end