1 files changed, 59 insertions, 0 deletions
diff --git a/lib/gitlab/pagination/keyset/in_operator_optimization/array_scope_columns.rb b/lib/gitlab/pagination/keyset/in_operator_optimization/array_scope_columns.rb
new file mode 100644
index 00000000000..95afd5a8595
--- /dev/null
+++ b/lib/gitlab/pagination/keyset/in_operator_optimization/array_scope_columns.rb
@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Pagination
+    module Keyset
+      module InOperatorOptimization
+        class ArrayScopeColumns
+          ARRAY_SCOPE_CTE_NAME = 'array_cte'
+
+          def initialize(columns)
+            validate_columns!(columns)
+
+            array_scope_table = Arel::Table.new(ARRAY_SCOPE_CTE_NAME)
+            @columns = columns.map do |column|
+              ColumnData.new(column, "array_scope_#{column}", array_scope_table)
+            end
+          end
+
+          def array_scope_cte_name
+            ARRAY_SCOPE_CTE_NAME
+          end
+
+          def array_aggregated_columns
+            columns.map(&:array_aggregated_column)
+          end
+
+          def array_aggregated_column_names
+            columns.map(&:array_aggregated_column_name)
+          end
+
+          def arel_columns
+            columns.map(&:arel_column)
+          end
+
+          def array_lookup_expressions_by_position(table_name)
+            columns.map do |column|
+              Arel.sql("#{table_name}.#{column.array_aggregated_column_name}[position]")
+            end
+          end
+
+          private
+
+          attr_reader :columns
+
+          def validate_columns!(columns)
+            if columns.blank?
+              msg = <<~MSG
+              No array columns were given.
+              Make sure you explicitly select the columns in the array_scope parameter.
+              Example: Project.select(:id)
+              MSG
+              raise StandardError, msg
+            end
+          end
+        end
+      end
+    end
+  end
+end