内部交流写的PDF：
http://space.itpub.net/?uid-8242091-action-viewspace-itemid-676943

可能对研究ORACLE内部机理有所帮助，有兴趣的可以一起研究下

下面是个例子：跟踪ORACLE逻辑读读了那些数据块：

SQL> alter session set events 'immediate debug';
GNU gdb Red Hat Linux (6.3.0.0-1.63rh)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-redhat-linux-gnu".
Attaching to process 27020
Reading symbols from /oracle10/product/10.2/bin/oracle...(no debugging symbols found)...done.
Using host libthread_db library "/lib/libthread_db.so.1".
Reading symbols from /lib/libcwait.so...(no debugging symbols found)...done.
Loaded symbols for /lib/libcwait.so
Reading symbols from /oracle10/product/10.2/lib/libskgxp10.so...(no debugging symbols found)...done.
Loaded symbols for /oracle10/product/10.2/lib/libskgxp10.so
Reading symbols from /oracle10/product/10.2/lib/libhasgen10.so...done.
Loaded symbols for /oracle10/product/10.2/lib/libhasgen10.so
Reading symbols from /oracle10/product/10.2/lib/libskgxn2.so...done.
Loaded symbols for /oracle10/product/10.2/lib/libskgxn2.so
Reading symbols from /oracle10/product/10.2/lib/libocr10.so...done.
Loaded symbols for /oracle10/product/10.2/lib/libocr10.so
Reading symbols from /oracle10/product/10.2/lib/libocrb10.so...done.
Loaded symbols for /oracle10/product/10.2/lib/libocrb10.so
Reading symbols from /oracle10/product/10.2/lib/libocrutl10.so...done.
Loaded symbols for /oracle10/product/10.2/lib/libocrutl10.so
Reading symbols from /oracle10/product/10.2/lib/libjox10.so...done.
Loaded symbols for /oracle10/product/10.2/lib/libjox10.so
Reading symbols from /oracle10/product/10.2/lib/libclsra10.so...done.
Loaded symbols for /oracle10/product/10.2/lib/libclsra10.so
Reading symbols from /oracle10/product/10.2/lib/libdbcfg10.so...done.
Loaded symbols for /oracle10/product/10.2/lib/libdbcfg10.so
Reading symbols from /oracle10/product/10.2/lib/libnnz10.so...done.
Loaded symbols for /oracle10/product/10.2/lib/libnnz10.so
Reading symbols from /usr/lib/libaio.so.1...done.
Loaded symbols for /usr/lib/libaio.so.1
Reading symbols from /lib/libdl.so.2...done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /lib/i686/libm.so.6...done.
Loaded symbols for /lib/i686/libm.so.6
Reading symbols from /lib/i686/libpthread.so.0...done.
[Thread debugging using libthread_db enabled]
[New Thread 16384 (LWP 27020)]
Loaded symbols for /lib/i686/libpthread.so.0
Reading symbols from /lib/libnsl.so.1...done.
Loaded symbols for /lib/libnsl.so.1
Reading symbols from /lib/i686/libc.so.6...done.
Loaded symbols for /lib/i686/libc.so.6
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /usr/lib/libnuma.so...done.
Loaded symbols for /usr/lib/libnuma.so
Reading symbols from /lib/libnss_files.so.2...done.
Loaded symbols for /lib/libnss_files.so.2
0xb74126c1 in __pthread_fork ()
   from /lib/i686/libpthread.so.0
(gdb) Breakpoint 1 at 0x8b03e59
(gdb)  > > >0xb7407c24 <__fork_block+4>:        0x00000000

Session altered.

SQL> select /*+full(a) */ count(*) from hr.employees a;
[Switching to Thread 16384 (LWP 27020)]

Breakpoint 1, 0x08b03e59 in kcbgtcr ()
0xbfffb64c:     0x010013cb

Breakpoint 1, 0x08b03e59 in kcbgtcr ()
0xbfffb39c:     0x010013cb

Breakpoint 1, 0x08b03e59 in kcbgtcr ()
0xb71169a0:     0x010013cc

Breakpoint 1, 0x08b03e59 in kcbgtcr ()
0xb71169a0:     0x010013cd

Breakpoint 1, 0x08b03e59 in kcbgtcr ()
0xb71169a0:     0x010013ce

---Type to continue, or q to quit---
Breakpoint 1, 0x08b03e59 in kcbgtcr ()
0xb71169a0:     0x010013cf

Breakpoint 1, 0x08b03e59 in kcbgtcr ()
0xb71169a0:     0x010013d0

  COUNT(*)
----------
       108