Format of origin queue ID

Each record in the transaction log is identified by an origin queue ID that consists of 64 hexadecimal characters (32 bytes). The format of the origin queue ID is determined by the Replication Agent instance, and it varies according to the primary database type.

Table 3-1 illustrates the format of the origin queue ID for the Replication Agent for Oracle.

**Table 3-1: Replication Agent for Oracle origin queue ID**
Character	Bytes	Description
0-3	2	Database generation ID
4-19	8	System change number
20-27	4	Log sequence number
28-35	4	Block number
36-39	2	Block offset, relative to the start of the block
40-47	4	Oldest active transaction begin log sequence number
48-55	4	Oldest active transaction begin block number
56-59	2	Oldest active transaction begin block offset
60-63	2	Available for specifying uniqueness