There's a mistake in the last mail.
About how to reproduct the issue,the following SQL should be:
set enable_seqscan = false;
4. execute select SQLset enable_seqscan = false;select count(*) from tb1 where id =2;Regard,Chen Huajun
4. execute select SQLset enable_seqscan = false;select count(*) from tb1 where id =2;Regard,Chen Huajun