How Resumable Space

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How Resumable Space Allocation Works

 

The following is an overview of how resumable space allocationworks. Details are contained in later sections.

1. A statement executes in a resumable mode only if its session hasbeen enabled for resumable space allocation by one of the followingactions:

   • The RESUMABLE_TIMEOUT initialization parameteris set to a nonzero value.

   • The ALTER SESSION ENABLE RESUMABLE statement isissued.

2. A resumable statement is suspended when one of thefollowing conditions occur (these conditions result incorresponding errors being signalled for non-resumablestatements):

   • Out of space condition

   • Maximum extents reachedcondition(包括一个段的最大区间数达到的时候，会触发resumable,在视图Dba_Segments中可以查看到字段max_extents，即该列为段的最大区间数。）

   • Space quota exceeded condition.

---这是触发的条件：以上三个(总之，遇上空间问题，如果配置了 resumable的，那么会话会被挂起一定的时间。）

1. When the execution of a resumable statement is suspended, thereare mechanisms to perform user supplied operations, log errors, andto query the status of the statement execution. When a resumablestatement is suspended the following actions are taken:

   • The error is reported in the alert log.

   • The system issues the Resumable Session Suspended alert.

   • If the user registered a trigger on the AFTERSUSPEND system event, the user trigger is executed. A usersupplied PL/SQL procedure can access the error message data usingtheDBMS_RESUMABLE package and the DBA_or USER_RESUMABLE view.

2. Suspending a statement automatically results in suspending thetransaction. Thus all transactional resources are held through astatement suspend and resume.

3. When the error condition is resolved (for example, as a resultof user intervention or perhaps sort space released by otherqueries), the suspended statement automatically resumes executionand the Resumable Session Suspended alert is cleared.

4. A suspended statement can be forced to throw the exception usingthe DBMS_RESUMABLE.ABORT() procedure. This procedurecan be called by a DBA, or by the user who issued thestatement.

5. A suspension time out interval is associated with resumablestatements. A resumable statement that is suspended for the timeoutinterval (the default is two hours) wakes up and returns theexception to the user.

6. A resumable statement can be suspended and resumed multipletimes during execution.