Shulou(Shulou.com)05/31 Report--

This article will explain in detail about the use of NESTED_TABLE_SET_REFS hint in the database. The editor thinks it is very practical, so I share it for you as a reference. I hope you can get something after reading this article.

NESTED_TABLE_SET_REFS hint is equivalent to the operation of data pump expdp and impdp

INSERT / * + NESTED_TABLE_SET_REFS+*/

An undisclosed hint prompt for Oracle appears in front of me. If you look at the background application corresponding to this session, it turns out that it is an export operation, but I really haven't noticed it before. I found the following explanation on metalink:

This hint specifies that nested tables should be retrieved as refs.It is used for exporting, importing and loading. It should never be issued by

User queries, and in fact is unlikely to make a difference if tried.

This is also consistent with seeing large amounts of queries with this hint, and that those queries are not reused. If this is a problem for you, try to export at another time of day. If the exports are really long-running or the system load is constant, try to find out what you are using exports for and suggest alternatives (eg. Backup and recovery purposes, etc). If this is a DSS system, you probably have a smaller shared pool and use import/export heavily. If so, it might be a good idea to use a bigger shared pool when doing this activity.

This is the end of the article on "what is the use of NESTED_TABLE_SET_REFS hint in the database". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it out for more people to see.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.