| Undo段中區的狀態free ??????expiredinactiveactive ??????顯示UNDO區信息 ??????SELECT?extent_?id,?bytes，?status?FROM?dba_?_undo_?_extentsWHERE?segment_?name='?SYSSMU1S'?; ??????圖解一一個事務的操作流程 ??????Undo段的組成:段頭、回滾塊 ??????事務ID ??????select?xid,?xidusn,?xidslot,?xidsqn,?ubab1k,?ubafil?from?vStransaction;事務表 ??????undo段的第一一個?數據塊，每一個回滾段最多可以47個事務回滾段的段頭塊 ??????select?*?from?vSro1?lname; ??????select?header.?block,?header_?file?from?dba?segments?where?segment_?_name='_?SYSSMU1S'?;alter?system?dump?undo?header，SYSSMU1S'?:/轉儲回滾段頭Ialter?system?dump?datafile?5?block?4308;//轉儲回滾段數據塊事務槽:?xid、uba | ? |
| select?spid?from?v$process?where?addr?in??(select?paddr?from?v$session?where sid=(select?sid?from?v$mystat?where?rownum=1))?; | ? |
| ? | ? |
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