Hi Larry,

the lb (lock byte) in the row piece of the block points to an ITL entry.

As for the ITL entry, there is a slight confusion in that the headings don't
line up exactly with values.  In your case, when uncommitted, the contents
are :


Itl             0x01                                            (ITL no.)
Xid         xid:  0x0002.018.00000482           (transaction ID)
Uba         uba: 0x0080c4a8.0340.0e                     (undo block address)
Flag    ----                                            (state of
transaction)
Lck             1                                               (no. of rows
locked by this transaction within this block)
Scn/Fsc fsc 0x0006.00000000                     (SCN or Free Space Credit)

Steve Adams and Jonathan Lewis' sites have some info on block dumps.  Also,
"Scaling Oracle 8i" by James Morle also has some info.

HTH, 
Paul


-----Original Message-----
Sent: Tuesday, December 04, 2001 12:36 PM
To: Multiple recipients of list ORACLE-L


Listers,

Playing around with dumping a block to determine rows which are locked. I
did an update to a single row in a table and did not commit. I dumped the
block. Here is the relevant info:

tab 0, row 0, @0x19c3
tl: 21 fb: --H-FL-- lb: 0x1 cc: 3

After rolling back and dumping the block, I get the following:

tab 0, row 0, @0x1977
tl: 27 fb: --H-FL-- lb: 0x0 cc: 3

It looks like to me that the "lb:" value indicates the presence of a lock on
the row -- 0x1 for a lock, 0x0 for not locked. I've been googling for a bit,
searching usenet, and the typical web sites for info on this and came up
empty handed. So, can anyone confirm this idea of lb: 0x0 meaning no lock
and 0x1 meaning the row is locked?

Also, there seems to be some differences in the block header info related to
ITL's:

Lock present:

 Itl           Xid                  Uba         Flag  Lck        Scn/Fsc
0x01   xid:  0x0002.018.00000482    uba: 0x0080c4a8.0340.0e  ----    1  fsc
0x0006.00000000

No lock:

 Itl           Xid                  Uba         Flag  Lck        Scn/Fsc
0x01   xid:  0x0001.037.000004c3    uba: 0x00800107.06dc.31  C---    0  scn
0x0000.00594c1b

Can I assume that Scn/Fsc value of non-zero means there is a lock? And last
but not least, any good info anywhere on reading block dumps?

Regards,

Larry G. Elkins
[EMAIL PROTECTED]
214.954.1781

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