方便的话提供一下您的测试语句和数据库小版本号（select id_code();）,我们复现一下这个问题

union all语句嵌套层数是有限制的，嵌套层数最好不要超过90.建议这么修改下
select a from dual
union all
select a from dual
union all
…
…
union all
select a from dual
修改为
select * from(
select a from dual
union all
…
…
union all
select a from dual)

union all
select * from (
select a from dual
union all
…
…
union all
select a from dual)