10分钟后，他通过QQ把TRACE发过来了： SELECT * FROM ttt where rownum<100
call count cpu elapsed disk query currentrows
------- ------ -------- ---------- -------------------- ---------- ----------
Parse 1 0.14 0.17 44 198 0 0
Execute 1 0.00 0.00 0 0 0 0
Fetch 8 3.71 5.86 67489 68340 0 99
------- ------ -------- -------------------- ---------- ---------- ----------
total 10 3.85 6.03 67533 68538 0 99
从这上面看，确实产生了67533个物理读和68538个逻辑读。执行时间为6.03秒。从等待事件来看：
BINDS #39:
EXEC #39:c=0,e=88,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,tim=1422207486718
WAIT #39: nam='SQL*Net message to client'ela= 7 driver id=1650815232 #bytes=1 p3=0 obj#=206418 tim=1422207486810
WAIT #39: nam='SQL*Net more data to client'ela= 203 driver id=1650815232 #bytes=2002 p3=0 obj#=206418 tim=1422207487071
WAIT #39: nam='SQL*Net more data to client'ela= 66 driver id=1650815232 #bytes=2020 p3=0 obj#=206418 tim=1422207487175
WAIT #39: nam='db file scattered read' ela=515 file#=146 block#=92900 blocks=5 obj#=206418 tim=1422207488208
WAIT #39: nam='db file scattered read' ela=918 file#=146 block#=92905 blocks=8 obj#=206418 tim=1422207489579
WAIT #39: nam='db file scattered read' ela=2121 file#=146 block#=92914 blocks=7 obj#=206418 tim=1422207492091
WAIT #39: nam='db file scattered read' ela=617 file#=146 block#=92921 blocks=8 obj#=206418 tim=1422207493135
WAIT #39: nam='db file scattered read' ela=493 file#=146 block#=92930 blocks=7 obj#=206418 tim=1422207494016
WAIT #39: nam='db file scattered read' ela=1666 file#=147 block#=897417 blocks=8 obj#=206418 tim=1422207496049
WAIT #39: nam='db file scattered read' ela=1026 file#=147 block#=897426 blocks=7 obj#=206418 tim=1422207497350
WAIT #39: nam='db file scattered read' ela=378 file#=147 block#=897433 blocks=8 obj#=206418 tim=1422207498049
WAIT #39: nam='db file scattered read' ela=1075 file#=147 block#=897442 blocks=7 obj#=206418 tim=1422207499416
WAIT #39: nam='db file scattered read' ela=1649 file#=147 block#=897449 blocks=3 obj#=206418 tim=1422207501237
WAIT #39: nam='db file scattered read' ela=2768 file#=147 block#=897453 blocks=4 obj#=206418 tim=1422207504191
WAIT #39: nam='db file scattered read' ela=653 file#=147 block#=897458 blocks=7 obj#=206418 tim=1422207505141
WAIT #39: nam='db file scattered read' ela=1588 file#=147 block#=897465 blocks=8 obj#=206418 tim=1422207507029
WAIT #39: nam='db file scattered read' ela=460 file#=147 block#=897474 blocks=7 obj#=206418 tim=1422207507787
WAIT #39: nam='db file scattered read' ela=608 file#=147 block#=897481 blocks=8 obj#=206418 tim=1422207508697
WAIT #39: nam='db file scattered read' ela=564 file#=147 block#=897490 blocks=7 obj#=206418 tim=1422207509571
WAIT #39: nam='db file scattered read' ela=832 file#=147 block#=897497 blocks=8 obj#=206418 tim=1422207510668
WAIT #39: nam='db file scattered read' ela=846 file#=148 block#=102411 blocks=16 obj#=206418 tim=1422207512030
WAIT #39: nam='db file scattered read' ela=4872 file#=148 block#=102427 blocks=16 obj#=206418 tim=1422207517488
WAIT #39: nam='db file scattered read' ela=1624 file#=148 block#=102443 blocks=16 obj#=206418 tim=1422207520062
确实存在大量的DB FILE SCATTERD READ。这更加坚信了我的观点，表里存在大量的碎片。找第一个SCATTERD READ的参数 file#=146 block#=92900，让客户执行alter system dump datafile 146 block min 92900 block max 92904。
获得的结果如下：
data_block_dump,data header at0x6000000000208e64
===============
tsiz: 0x1f98
hsiz: 0x4c
pbl: 0x6000000000208e64
bdba: 0x248