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 Oracle BBED - The Block Browser and Editor Tools
Oracle Tips by Burleson Consulting

Advanced Oracle Utilities: The Definitive Reference by Rampant TechPress is written by four of the top Oracle database experts (Bert Scalzo, Donald Burleson, and Steve Callan).  The following is an excerpt from the book.

What if one could directly read and manipulate data at the block level? Oracle provides such a tool to do exactly that, but it has to be built by the DBA. The Block Browser and Editor tool, or bbed for short, is the ticket into the contents of data blocks within an Oracle database. Here is what can be done with bbed:

  • Change data

  • Recover damaged or deleted data

  • Alter a file header

  • Corrupt and uncorrupt a block

The ability to change data is what it sounds like. Any data can be changed anywhere. What does this imply? It also means that passwords can be changed – any password. For example, the password for sys can be changed.

 

Deleted a row and need to recover it? What happens to data when the DBA or a user deletes it? Specifically, does the data really go away, or does something else take place? The answer is that something else takes place. Oracle marks the row(s) as deleted and makes the space available for use in the future. For example, when using files in DOS and a file was deleted, the first character of the file name was changed and the file became hidden to normal “dir” listings. Recovery tools could be used to show deleted files; the only real work was to figure out what the missing first character was. Recovering data in Oracle using bbed is roughly the same thing – one just has to find where the deleted row lives and reset some flags to make the row active again as long as the row has not been overwritten yet.

 

On a larger scale, the same type of recovery can be done using data files. By setting values inside the file header (the file header block), an older file can become part of the current database.

 

The bbed utility also gives one the power to corrupt and uncorrupt a block or reset the corrupt block marker. Use of bbed for this purpose, although interesting, is not practical in that there are better, i.e. more established and approved, ways of repairing corrupt blocks. However, if one wants to corrupt a block and test out one’s RMAN skills, this would be a fairly quick way to set up that lab environment.

 

All of the above can be done without having access to a database in terms of being logged in or having an active instance running except for the RMAN recovery. In other words, if someone has access to bbed and access to one’s datafiles, that person has access to everything in the database. Everything. If that does not convince one to safeguard the Oracle datafiles from unauthorized users, what will?

 

Where and how does one get bbed? In UNIX, Oracle gives the pieces needed to create the tool. The DBA does not get bbed as a live or active executable like what one gets with EXP or SQL*Plus. In older versions of Oracle on Windows, the executable was installed ready for use, but this is no longer the case.  It did not even have to be the RDBMS installation to get BBED.EXE (how it is named on Windows). Using an Oracle8i client installation, BBED.EXE is installed in $ORACLE_HOME/bin by default.

In a 32-bit installation on UNIX (refers to all *NIX variants), look for two object files in $ORACLE_HOME/rdbms/lib: sbbdpt.o and ssbbded.o. In a 64-bit installation, the files will be in the lib32 directory.

 

[oracle] ls -la *bb*.o

-rw-r--r--    1 oracle   dba          1160 Nov 18  2003 sbbdpt.o

-rw-r--r--    1 oracle   dba           848 Nov 18  2003 ssbbded.o

 

To create or make the executable, use the make command as shown.

[oracle] make -f ins_rdbms.mk $ORACLE_HOME/rdbms/lib/bbed

 

Sample output from the make command is shown below.

 

Linking BBED utility (bbed)

rm -f /u001/app/oracle/ora904/rdbms/lib/bbed

gcc -o /u001/app/oracle/ora904/rdbms/lib/bbed -L/u001/app/oracle/ora904/rdbms/lib/ -L/u001/app/oracle/ora904/lib/  /u001/app/oracle/ora904/lib/s0main.o /u001/app/oracle/ora904/rdbms/lib/ssbbded.o /u001/app/oracle/ora904/rdbms/lib/sbbdpt.o `cat /u001/app/oracle/ora904/lib/ldflags`    -lnsslb9 -lncrypt9 -lnsgr9 -lnzjs9 -<some lines removed>

lcommon9 -lgeneric9  -ltrace9 -lnls9  -lcore9 -lnls9 -lcore9 -lnls9 -lxml9 -lcore9 -lunls9 -lclient9  -lvsn9 -lwtc9 -lcommon9 -lgeneric9 -lnls9  -lcore9 -lnls9 -lcore9 -lnls9 -lxml9 -lcore9 -lunls9   `cat /u001/app/oracle/ora904/lib/sysliblist` -Wl,-rpath,/u001/app/oracle/ora904/lib:/lib:/usr/lib -lm    `cat /u001/app/oracle/ora904/lib/sysliblist` -ldl -lm

     

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