All DB2 common server log records begin with a log manager header.
This header contains information detailing the log record and transaction
information of the log record writer.
| Description
| Type
| Offset (Bytes)
|
| Length of the entire log record
| int
| 0(4)
|
| Type of log recorda
| short
| 4(2)
|
| Log record general flagb
| short
| 6(2)
|
| Log Sequence Number of the previous log record written by this
transaction. It is used to chain log records by transaction. If
the value is 0000 0000 0000, this is the first log record written by the
transaction.
| SQLU_LSNc
| 8(6)
|
| Unique transaction identifier
| SQLU_TIDd
| 14(6)
|
| Log Sequence Number of the log record for this transaction prior to the
log record being compensated. (Note: For compensation and backout
free log records only.)
| SQLU_LSN
| 20(6)
|
| Log Sequence Number of the log record for this transaction being
compensated. (Note: For propagatable compensation log records
only.)
| SQLU_LSN
| 26(6)
|
Total Length for Log Manager Log Record Header:
- Non Compensation: 20 bytes
- Compensation: 26 bytes
- Propagatable Compensation: 32 bytes
|
- a Valid log record types
a Datalink manager log record o Backup start
A Normal abort O Backup end
B Backout free p Tablespace roll forward to PIT starts
c MPP coordinator commit P Table quiesce
C Compensation q Tablespace roll forward to PIT ends
D Tablespace rolled forward Q Global pending list
E Local pending list R Redo
F Forget transaction s MPP subordinate commit
g MPP log synchronization S Compensation required
G Load pending list T Partial abort
H Table load delete start U Undo
i Propagate only V Migration begin
I Heuristic abort W Migration end
J Load start X TM prepare
K Load delete start compensation Y Heuristic commit
L Lock description z MPP prepare
M Normal commit Z XA prepare
N Normal
Note: A log record of type 'i' is an informational log record only.
It will be ignored by DB2 during roll forward, roll back,
and crash recovery.
- b Log record general flag constants
Redo Always 0x0001
Propagatable 0x0002
Conditionally Recoverable 0x0080
- c Log Sequence Number (LSN)
A unique log record identifier representing the relative byte address
of the log record within the database log.
SQLU_LSN: union { char [6] ;
short [3] ;
}
- d Transaction Identifier (TID)
A unique log record identifier representing the transaction.
SQLU_TID: union { char [6] ;
short [3] ;
}
|
