Restore fails with the following:
Error writing to database

More information about this error

Debug info: Data too long for column 'subquestions' at row 1
UPDATE mdl_question_match SET subquestions = ? WHERE id = ?
[array (
0 => '750773,750774,750775,750776,750777,750778,750779,750780,750781,750782,750783,750784,750785,750786,750787,750788,750789,750790,750791,750792,750793,750794,750795,750796,750797,750798,750799,750800,750801,750802,750803,750804,750805,750806,750807,750808,750809,750810,750811,750812,750813,750814',
1 => '63860',
)]
Error code: dmlwriteexception
Stack trace:
line 429 of /lib/dml/moodle_database.php: dml_write_exception thrown
line 1285 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
line 1565 of /lib/dml/moodle_database.php: call to mysqli_native_moodle_database->set_field_select()
line 195 of /question/type/match/backup/moodle2/restore_qtype_match_plugin.class.php: call to moodle_database->set_field()
line 84 of /backup/moodle2/restore_plugin.class.php: call to restore_qtype_match_plugin->after_execute_question()
line 362 of /backup/util/plan/restore_structure_step.class.php: call to restore_plugin->launch_after_execute_methods()
line 108 of /backup/util/plan/restore_structure_step.class.php: call to restore_structure_step->launch_after_execute_methods()
line 153 of /backup/util/plan/base_task.class.php: call to restore_structure_step->execute()
line 163 of /backup/util/plan/base_plan.class.php: call to base_task->execute()
line 157 of /backup/util/plan/restore_plan.class.php: call to base_plan->execute()
line 315 of /backup/controller/restore_controller.class.php: call to restore_plan->execute()
line 147 of /backup/util/ui/restore_ui.class.php: call to restore_controller->execute_plan()
line 46 of /backup/restore.php: call to restore_ui->execute()

This appears to be related to the character limit on subquestions:

As the subquestions auto increment up, on a heavily used site, the id's are now 6 characters long:

select id, subquestions from mdl_question_match order by id desc limit 3;
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As a result, restoring courses with a large number of subquestions is now failing.