Obtain the global transaction identifier

When a global transaction starts, it receives a unique identification number called a global transaction identifier (GTRID). The GTRID includes the name of the coordinator. The GTRID is written to the BEGPREP logical-log record of the coordinator and the PREPARE logical-log record of each participant.

To see the GTRID, use the onlog -l option. The GTRID is offset 20 bytes into the data portion of the record and is 144 bytes long. The following example shows the onlog -l output for a BEGPREP record. The coordinator is chrisw.

4a064    188  BEGPREP  4        0  4a038       0    1
         000000bc 00000043 00000004 0004a038 .......C .......8
         00087ef0 00000002 63687269 73770000 ..~..... chrisw..
         00000000 00000000 00000000 00087eeb ........ ......~.
         00006b16 00000000 00000000 00000000 ..k..... ........
         00000000 00000000 00000000 00000000 
         00000000 00000000 00000000 00000000 
         00000000 00000000 00000000 00000000 
         00000000 00000000 00000000 00000000 
         00000000 00000000 00000000 00000000 
         00000000 00000000 00000000 00000000 
         00000000 00000001 6a756469 74685f73 ........ judith_s
         6f630000 736f6374 63700000          oc..soct cp..

The first 32 bytes of the GTRID are identical for the BEGPREP record on the coordinator and the PREPARE records on participants, which are part of the same global transaction. For example, compare the GTRID for the PREPARE record in the following example with that of the BEGPREP record in the previous example.

c7064    184  PREPARE  4        0  c7038    chrisw
         000000b8 00000044 00000004 000c7038 .......D ......p8
         00005cd6 00000002 63687269 73770000 ...... chrisw..
         00000000 00000000 00000069 00087eeb ........ ...i..~.
         00006b16 00000000 00000010 00ba5a10 ..k..... ......Z.
         00000002 00ba3a0c 00000006 00000000 ......:. ........
         00ba5a10 00ba5a1c 00000000 00000000 ..Z...Z. ........
         00ba3a0e 00254554 00ba2090 00000001 ..:..%ET .. .....
         00000000 00ab8148 0005fd70 00ab8148 .......H ...p...H
         0005fe34 0000003c 00000000 00000000 ...4...< ........
         00000000 00ab80cc 00000000 00ab80c4 ........ ........
         00ba002f 63687269 73770000 00120018 .../chrisw......
         00120018 00ba0000                   ........