Positioning Extract to a Specific Start Point

You can position the Extract to a specific start point in the transaction logs using the ADD/ALTER EXTRACT commands:

{ADD | ALTER EXTRACT} group, LOGNUM log_num, LOGPOS log_pos

• group is the name of the Oracle GoldenGate Extract group for which the start position is required.

• LOGNUM is the log file number. For example, if the required log file name is test.000034, the LOGNUM value is 34. Extract will search for this log file.

  Note:

  In Microservices Architecture, ADD EXTRACT will fail if the LOGNUM value contains zeroes preceding the value. For example, ADD EXTRACT ext1, TRANLOG, LOGNUM 000001, LOGPOS 0 will fail. Instead, set LOGNUM to 1 for this example to succeed.

• LOGPOS is an event offset value within the log file that identifies a specific transaction record. Event offset values are stored in the header section of a log record. To position at the beginning of a binlog file, set the LOGPOS as 0.

In MySQL logs, an event offset value can be unique only within a given binary file. The combination of the position value and a log number will uniquely identify a transaction record. Maximum Log number length is 8 bytes unsigned integer and Maximum Log offset length is 8 bytes unsigned integer. Log number and Log offset are separated by a pipe (‘|’) delimiter. Transactional records available after this position within the specified log will be captured by Extract. In addition, you can position an Extract using a timestamp.