1 files changed, 0 insertions, 102 deletions
diff --git a/lib/gitlab/database/loose_index_scan_distinct_count.rb b/lib/gitlab/database/loose_index_scan_distinct_count.rb
deleted file mode 100644
index 26be07f91c4..00000000000
--- a/lib/gitlab/database/loose_index_scan_distinct_count.rb
+++ /dev/null
@@ -1,102 +0,0 @@
-# frozen_string_literal: true
-
-module Gitlab
-  module Database
-    # This class builds efficient batched distinct query by using loose index scan.
-    # Consider the following example:
-    # > Issue.distinct(:project_id).where(project_id: (1...100)).count
-    #
-    # Note: there is an index on project_id
-    #
-    # This query will read each element in the index matching the project_id filter.
-    # If for a project_id has 100_000 issues, all 100_000 elements will be read.
-    #
-    # A loose index scan will only read one entry from the index for each project_id to reduce the number of disk reads.
-    #
-    # Usage:
-    #
-    # Gitlab::Database::LooseIndexScanDisctinctCount.new(Issue, :project_id).count(from: 1, to: 100)
-    #
-    # The query will return the number of distinct projects_ids between 1 and 100
-    #
-    # Getting the Arel query:
-    #
-    # Gitlab::Database::LooseIndexScanDisctinctCount.new(Issue, :project_id).build_query(from: 1, to: 100)
-    class LooseIndexScanDistinctCount
-      COLUMN_ALIAS = 'distinct_count_column'
-
-      ColumnConfigurationError = Class.new(StandardError)
-
-      def initialize(scope, column)
-        if scope.is_a?(ActiveRecord::Relation)
-          @scope = scope
-          @model = scope.model
-        else
-          @scope = scope.where({})
-          @model = scope
-        end
-
-        @column = transform_column(column)
-      end
-
-      def count(from:, to:)
-        build_query(from: from, to: to).count(COLUMN_ALIAS)
-      end
-
-      def build_query(from:, to:) # rubocop:disable Metrics/AbcSize
-        cte = Gitlab::SQL::RecursiveCTE.new(:counter_cte, union_args: { remove_order: false })
-        table = model.arel_table
-
-        cte << @scope
-          .dup
-          .select(column.as(COLUMN_ALIAS))
-          .where(column.gteq(from))
-          .where(column.lt(to))
-          .order(column)
-          .limit(1)
-
-        inner_query = @scope
-          .dup
-          .where(column.gt(cte.table[COLUMN_ALIAS]))
-          .where(column.lt(to))
-          .select(column.as(COLUMN_ALIAS))
-          .order(column)
-          .limit(1)
-
-        cte << cte.table
-          .project(Arel::Nodes::Grouping.new(Arel.sql(inner_query.to_sql)).as(COLUMN_ALIAS))
-          .where(cte.table[COLUMN_ALIAS].lt(to))
-
-        model
-          .with
-          .recursive(cte.to_arel)
-          .from(cte.alias_to(table))
-          .unscope(where: :source_type)
-          .unscope(where: model.inheritance_column) # Remove STI query, not needed here
-      end
-
-      private
-
-      attr_reader :column, :model
-
-      # Transforms the column so it can be used in Arel expressions
-      #
-      # 'table.column' => 'table.column'
-      # 'column' => 'table_name.column'
-      # :column => 'table_name.column'
-      # Arel::Attributes::Attribute => name of the column
-      def transform_column(column)
-        if column.is_a?(String) || column.is_a?(Symbol)
-          column_as_string = column.to_s
-          column_as_string = "#{model.table_name}.#{column_as_string}" unless column_as_string.include?('.')
-
-          Arel.sql(column_as_string)
-        elsif column.is_a?(Arel::Attributes::Attribute)
-          column
-        else
-          raise ColumnConfigurationError, "Cannot transform the column: #{column.inspect}, please provide the column name as string"
-        end
-      end
-    end
-  end
-end