Oracle ORA-00600 [4193] ORA-600 [4193] “seq# mismatch while adding undo record”

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Format: ORA-600 [4193] [a] [b]


versions 6.0 to 10.1

A mismatch has been detected between Redo records and Rollback (Undo) records.
We are validating the Undo block sequence number in the undo block against the Redo block sequence number relating to the change being applied.

This error is reported when this validation fails.

Arg [a] Undo record seq number
Arg [b] Redo record seq number






This error may indicate a rollback segment corruption.
This may require a recovery from a database backup depending on the situation.


NB Bug Fixed Description
14034244, Lost write type corruption using ASM in
Undo corruptions with ORA-600 [4193]/ORA-600 [4194] or ORA-600 [4137] /
SMON may spin to recover transaction


ORA-600 [4193] [a] [b] [ ] [ ] [ ]
Versions: 7.2.2 – 9.2.0 Source: ktuc.c
Meaning: seq# mismatch while adding an undo record to an undo block. This
is done by the application of redo.
Argument Description:
a. (ktubhseq): undo record seq# – this is the seq# of the block that
this undo record WILL BE APPLIED TO.
This is from the Undo Block. It is
NOT the seq# of the undo block itself.
b. (ktudbseq): redo RECORD seq# – this is the seq# number in the block
that this redo WILL BE APPLIED TO.
This is from the Redo Record.
This error is raised in kturdb which handles the adding of undo records
by the application of redo.
When we try to apply redo to an undo block (forward changes are made by
the application of redo to a block) we check that the seq# in the undo
record matches the seq# in the redo record. These seq# should be the
same because when we apply a redo record we must apply it to the
correct version of the block. We can only apply a redo record to a
block that contains the same seq# as in the redo record.
If the seq# do not match then this error is raised. This implies some
kind of block corruption in either the redo or the undo block.
7.3.x – 8.1.7.x
ASSERT2(ubh->ktubhseq == db->ktudbseq, OERI(4193), KSESVSGN,
ubh->ktubhseq, db->ktudbseq);
ksesic2(OERI(4193), ksenrg(ubh->ktubhseq), ksenrg(db->ktudbseq));
struct ktubh
kxid ktubhxid; /* txid of tx currently using or last used this block */
ub2 ktubhseq; /* undo block sequence number */
ub1 ktubhcnt; /* high water mark record index, number of undo entries */



ub1 ktubhirb; /* rollback record index, rec index to start the rollback */
ub1 ktubhicl; /* collecting record index, rec index to start retrieving col info */
ub1 ktubhflg; /* dummy */
ub2 ktubhidx[1]; /* byte offset of record in block, grows at runtime */
struct ktudb Kernel Transaction Undo Data operation Block (redo)
ub2 ktudbsiz; /* size of entry */
ub2 ktudbspc; /* verification: space left in undo block */
ub2 ktudbflg; /* flag to indicate the kind of redo operation */
kxid ktudbxid; /* current tx id */
ub2 ktudbseq; /* block sequence number */
ub1 ktudbrec; /* new record index for this change */
Note 452620.1 has a procedure to patch this inconsistency when the problem
is produced in the SYSTEM rollback segment
Known Bugs: (Those bugs that are fixed after version
(Bugs must be closed or hold useful information)
Fixed In. Bug No. Description
7.X Bug:XXXXXX Desc
ora-600 ora-600 ora-600 ora-600 ora-600 ora-600 ora-600
ora-600 ora-600 ora-600 ora-600 ora-600 ora-600 ora-600
4193 4193 4193 4193 4193 4193 4193 4193 4193 4193
4193 4193 4193 4193 4193 4193 4193 4193 4193 4193



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