about sql : select * from user_table object_id is null;
even though there is index about object_id , execution plan can not invoke index.
now you can create index text_id on user_table(object_id, 'a').
exp plain will use index, that will improve performance.
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/22936840/viewspace-749905/ ，如需转载，请注明出处，否则将追究法律责任。
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