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Home -> Community -> Mailing Lists -> Oracle-L -> RE: LOCKS - Reading Block Dumps
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/Fsc0x01 xid: 0x0002.018.00000482 uba: 0x0080c4a8.0340.0e ---- 1 fsc 0x0006.00000000
No lock:
Itl Xid Uba Flag Lck Scn/Fsc0x01 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
elkinsl_at_flash.net
214.954.1781
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Please see the official ORACLE-L FAQ: http://www.orafaq.com
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Author: Larry Elkins
INET: elkinsl_at_flash.net
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists --------------------------------------------------------------------To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists --------------------------------------------------------------------To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). Received on Tue Dec 04 2001 - 15:42:27 CST
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