单项选择题
A.gc buffer busy acquireB.gc buffer busy releaseC.gc current block 2-wayD.gc current block 3-way
A.control_filesB.memory_targetC.db_nameD.db_block_size
A.没有活动事务的block,一定不会出现ORA-01555B.当undo segment被删除时,一定会报ORA-01555C.块清除时匹配不到比snap_scn小的commit scn时,一定会报ORA-01555D.当undo段头事务表slot被重用时,一定会报ORA-01555