Use keyset pagination for fetching board issues [RUN ALL RSPEC] [RUN AS-IF-FOSS]

app/graphql/resolvers/board_list_issues_resolver.rb

@@ -16,7 +16,7 @@ module Resolvers
       filter_params = item_filters(args[:filters]).merge(board_id: list.board.id, id: list.id)
       service = ::Boards::Issues::ListService.new(list.board.resource_parent, context[:current_user], filter_params)
 
-      offset_pagination(service.execute)
+      service.execute
     end
 
     # https://gitlab.com/gitlab-org/gitlab/-/issues/235681

app/models/concerns/issuable.rb

@@ -332,12 +332,15 @@ module Issuable
       # When using CTE make sure to select the same columns that are on the group_by clause.
       # This prevents errors when ignored columns are present in the database.
       issuable_columns = with_cte ? issue_grouping_columns(use_cte: with_cte) : "#{table_name}.*"
+      group_columns = issue_grouping_columns(use_cte: with_cte) + ["highest_priorities.label_priority"]
 
-      extra_select_columns.unshift("(#{highest_priority}) AS highest_priority")
+      extra_select_columns.unshift("highest_priorities.label_priority as highest_priority")
 
       select(issuable_columns)
         .select(extra_select_columns)
-        .group(issue_grouping_columns(use_cte: with_cte))
+        .from("#{table_name}")
+        .joins("JOIN LATERAL(#{highest_priority}) as highest_priorities ON TRUE")
+        .group(group_columns)
         .reorder(Gitlab::Database.nulls_last_order('highest_priority', direction))
     end
 
@@ -384,7 +387,7 @@ module Issuable
       if use_cte
         attribute_names.map { |attr| arel_table[attr.to_sym] }
       else
-        arel_table[:id]
+        [arel_table[:id]]
       end
     end
 

app/models/concerns/sortable.rb

@@ -46,7 +46,7 @@ module Sortable
     private
 
     def highest_label_priority(target_type_column: nil, target_type: nil, target_column:, project_column:, excluded_labels: [])
-      query = Label.select(LabelPriority.arel_table[:priority].minimum)
+      query = Label.select(LabelPriority.arel_table[:priority].minimum.as('label_priority'))
         .left_join_priorities
         .joins(:label_links)
         .where("label_priorities.project_id = #{project_column}")

app/models/issue.rb

@@ -268,10 +268,41 @@ class Issue < ApplicationRecord
   # `with_cte` argument allows sorting when using CTE queries and prevents
   # errors in postgres when using CTE search optimisation
   def self.order_by_position_and_priority(with_cte: false)
+    order = Gitlab::Pagination::Keyset::Order.build([column_order_relative_position, column_order_highest_priority, column_order_id_desc])
+
     order_labels_priority(with_cte: with_cte)
-      .reorder(Gitlab::Database.nulls_last_order('relative_position', 'ASC'),
-              Gitlab::Database.nulls_last_order('highest_priority', 'ASC'),
-              "id DESC")
+      .reorder(order)
+  end
+
+  def self.column_order_relative_position
+    Gitlab::Pagination::Keyset::ColumnOrderDefinition.new(
+      attribute_name: 'relative_position',
+      column_expression: arel_table[:relative_position],
+      order_expression: Gitlab::Database.nulls_last_order('issues.relative_position', 'ASC'),
+      reversed_order_expression: Gitlab::Database.nulls_last_order('issues.relative_position', 'DESC'),
+      order_direction: :asc,
+      nullable: :nulls_last,
+      distinct: false
+    )
+  end
+
+  def self.column_order_highest_priority
+    Gitlab::Pagination::Keyset::ColumnOrderDefinition.new(
+      attribute_name: 'highest_priority',
+      column_expression: Arel.sql('highest_priorities.label_priority'),
+      order_expression: Gitlab::Database.nulls_last_order('highest_priorities.label_priority', 'ASC'),
+      reversed_order_expression: Gitlab::Database.nulls_last_order('highest_priorities.label_priority', 'DESC'),
+      order_direction: :asc,
+      nullable: :nulls_last,
+      distinct: false
+    )
+  end
+
+  def self.column_order_id_desc
+    Gitlab::Pagination::Keyset::ColumnOrderDefinition.new(
+      attribute_name: 'id',
+      order_expression: arel_table[:id].desc
+    )
   end
 
   # Temporary disable moving null elements because of performance problems

lib/gitlab/graphql/pagination/keyset/generic_keyset_pagination.rb

@@ -4,11 +4,42 @@ module Gitlab
   module Graphql
     module Pagination
       module Keyset
+        # https://gitlab.com/gitlab-org/gitlab/-/issues/334973
         # Use the generic keyset implementation if the given ActiveRecord scope supports it.
         # Note: this module is temporary, at some point it will be merged with Keyset::Connection
         module GenericKeysetPagination
           extend ActiveSupport::Concern
 
+          # rubocop: disable Naming/PredicateName
+          # rubocop: disable CodeReuse/ActiveRecord
+          def has_next_page
+            return super unless Gitlab::Pagination::Keyset::Order.keyset_aware?(items)
+
+            strong_memoize(:generic_keyset_pagination_has_next_page) do
+              if before
+                # If `before` is specified, that points to a specific record,
+                # even if it's the last one.  Since we're asking for `before`,
+                # then the specific record we're pointing to is in the
+                # next page
+                true
+              elsif first
+                case sliced_nodes
+                when Array
+                  sliced_nodes.size > limit_value
+                else
+                  # If we count the number of requested items plus one (`limit_value + 1`),
+                  # then if we get `limit_value + 1` then we know there is a next page
+                  sliced_nodes.limit(1).offset(limit_value).exists?
+                  # replacing relation count
+                  # relation_count(set_limit(sliced_nodes, limit_value + 1)) == limit_value + 1
+                end
+              else
+                false
+              end
+            end
+          end
+
+          # rubocop: enable CodeReuse/ActiveRecord
           def ordered_items
             raise ArgumentError, 'Relation must have a primary key' unless items.primary_key.present?
 

spec/lib/gitlab/graphql/pagination/keyset/connection_spec.rb

@@ -355,6 +355,10 @@ RSpec.describe Gitlab::Graphql::Pagination::Keyset::Connection do
     context 'when primary key is not in original order' do
       let(:nodes) { Project.order(last_repository_check_at: :desc) }
 
+      before do
+        stub_feature_flags(new_graphql_keyset_pagination: false)
+      end
+
       it 'is added to end' do
         sliced = subject.sliced_nodes