问题
I have read that in session tables the data survives the commit process. In words of Ask Tom.
the ON COMMIT PRESERVE ROWS makes this a session based temporary table. rows will stay in this table until a logoff. Only I can see them though, no other session will ever see 'my' rows even after I commit
The problem phrase for me here is "until a logoff". Take the case of a web application which maintains a single connection to DB. So this means that all users logged into the web application are going to share the same DB session. So, does this mean that all users are going to see the same content in that temporary table?
In a practical web application typically we maintain multiple DB connections. These connections are maintained in a "pool" and they are reused for many users. In this scenario then the behavior could be quite erratic and the user may view data populated by last user.
回答1:
Which is why Oracle provides an 'ON COMMIT DELETE ROWS' option as well.
Data in global temporary tables can have session scope (i.e. ON COMMIT PRESERVE ROWS) or transaction scope (ON COMMIT DELETE ROWS).
Clearly, in the case of connection pooling and shared servers/shared sessions, you'll want transaction scope (ON COMMIT DELETE ROWS).
Hope that helps.
来源：https://stackoverflow.com/questions/8240810/when-will-data-in-oracle-session-temporary-table-get-deleted