1 files changed, 42 insertions, 0 deletions
diff --git a/lib/gitlab/database/partitioning_migration_helpers/bulk_copy.rb b/lib/gitlab/database/partitioning_migration_helpers/bulk_copy.rb
new file mode 100644
index 00000000000..b8f5a2e3ad4
--- /dev/null
+++ b/lib/gitlab/database/partitioning_migration_helpers/bulk_copy.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Database
+    module PartitioningMigrationHelpers
+      # Helper class to copy data between two tables via upserts
+      class BulkCopy
+        DELIMITER = ', '
+
+        attr_reader :source_table, :destination_table, :source_column, :connection
+
+        def initialize(source_table, destination_table, source_column, connection:)
+          @source_table = source_table
+          @destination_table = destination_table
+          @source_column = source_column
+          @connection = connection
+        end
+
+        def copy_between(start_id, stop_id)
+          connection.execute(<<~SQL)
+            INSERT INTO #{destination_table} (#{column_listing})
+            SELECT #{column_listing}
+            FROM #{source_table}
+            WHERE #{source_column} BETWEEN #{start_id} AND #{stop_id}
+            FOR UPDATE
+            ON CONFLICT (#{conflict_targets}) DO NOTHING
+          SQL
+        end
+
+        private
+
+        def column_listing
+          @column_listing ||= connection.columns(source_table).map(&:name).join(DELIMITER)
+        end
+
+        def conflict_targets
+          connection.primary_keys(destination_table).join(DELIMITER)
+        end
+      end
+    end
+  end
+end