OBJ INDX ADDR HLADDR FLAG LRU_FLAG CLASS STATE DBARFIL DBABLK BA TCH
---------- ---------- ---------------- ---------------- ---------- ---------- ---------- ---------- ---------- ---------- ---------------- ----------
41231 9300 0000000110997C58 07000001B6AFD160 0 0 4 1 5 60682 070000015E0E2000 3
41231 17329 0000000110997C58 07000001BCC9B928 524288 0 1 1 5 60687 070000015F4AC000 3
41231 30337 0000000110997C58 07000001BCC9F230 524288 0 1 1 5 60684 070000015E2E8000 3
41231 51426 0000000110997C58 07000001BCCA5180 524288 0 1 1 5 60686 070000015F392000 3
41231 64237 0000000110997C58 07000001B6B0C908 524288 0 1 3 5 60683 0700000157EC0000 1
41231 64238 0000000110997B10 07000001B6B0C908 35651585 0 1 1 5 60683 070000015E1D6000 3
41231 64239 00000001109979C8 07000001B6B0C908 524288 2 1 3 5 60683 070000015E1D8000 1
41231 85256 0000000110997C58 07000001BCCAE9D8 524288 0 1 1 5 60685 070000015F268000 3
因为session 3执行的是consistent read，可以看到新增的BA=0700000157EC0000这行是5/60683的before-image，并没有复用同样是before-image的BA=070000015E1D8000这行
---session 3: 继续执行select
***查询5/60683的before-image个数
SYS@tstdb1-SQL> select obj,indx,addr,hladdr,flag,lru_flag,class,state,dbarfil,dbablk,ba,tch from x$bh where obj=41231 and dbablk=60683 and state=3;
OBJ INDX ADDR HLADDR FLAG LRU_FLAG CLASS STATE DBARFIL DBABLK BA TCH
---------- ---------- ---------------- ---------------- ---------- ---------- ---------- ---------- ---------- ---------- ---------------- ----------
41231 64258 0000000110997C58 07000001B6B0C908 524288 0 1 3 5 60683 0700000157EC0000 1
41231 64260 00000001109979C8 07000001B6B0C908 524288 2 1 3 5 60683 070000015E1D8000 1
select * from scott.t1118_1;