ADD EXTTRAIL

Use ADD EXTTRAIL to create a trail for online processing on the local system and:

Associate it with an Extract group.
Assign a maximum file size.
When attempting to create multiple trail files using ADD EXTTRAIL, from a single Extract process, the operation will fail if the number of trail files exceed a certain limit. Specifically, when more than 12 trails are created, the following error may occur:
```
2025-11-05T21:16:04Z  INFO    OGG-08100  Exceeded checkpoint record size (32,768/32,767) in

checkpoint file /path/to/checkpoint/file.cpe.
```
This error occurs due to the checkpoint file exceeding the size limit of 32,767 records. The checkpoint file contains CSN (Commit Sequence Number), XID (Transaction ID), and record numbers, which contribute to the file’s size.

To avoid this error it is recommended not to create multiple trail files from a single Extract, particularly for performance reasons. The preferred approach is to have a single Extract capture all required data and use the Distribution Service to distribute it to different destinations.

Another alternative option is to run multiple Extract processes if there is a need to reduce the trail file size for each individual destination.

See [EXTTRAIL](/pls/topic/lookup?ctx=en/database/goldengate/core/26/gclir&id=GWURF-GUID-6472A821-9470-4C83-A524-229BBC2FBD5C) in the Parameters and Functions Reference for Oracle GoldenGate

Syntax

ADD EXTTRAIL *trail_name*, EXTRACT *group_name*
[, MEGABYTES *n*]
[SEQNO *n*]

trail_name

A two character trail name. It is recommended that both the characters be alphabets, but the first character must not be a number. Oracle GoldenGate appends this name with a nine-digit sequence number whenever a new file is created.

The trail name can also be prefixed with a directory. For example, a trail named north/ea would have trail files named ea000000000, ea000000001 in the$OGG_DATA_HOME/north subdirectory.

group_name

The name of the Extract group to which the trail is bound. A trail can only be assigned to one Extract. Multiple Extracts cannot write to the same trail. However, one Extract can write to multiple distinct trails if needed, but this is not normally required.

MEGABYTES n

The maximum size, in megabytes, of each trail file in the sequence. The default is 500MB and the maximum value is 2000MB.

SEQNO n

Specifies that the first file in the trail will start with the specified trail sequence number. Do not include any zero padding. For example, to start at sequence 3 of a trail named tr, specify SEQNO 3. The actual file would be named /ea000000003. This option can be used during troubleshooting when a Replicat needs to be repositioned to a certain trail sequence number. It eliminates the need to alter the Replicat to read the required sequence number. The default value is 1.

Limitations

When creating an Extract trail with the same name as a prior Extract trail, make sure that all trails in that directory with the same trail_name have been deleted.

When capturing from a MySQL database enabled for group replication, only one trail is allowed for an Extract.

Examples

The following command creates a trail name ea:

ADD EXTTRAIL north/ea, EXTRACT exte, MEGABYTES 200

The output is displayed as follows:

2019-11-20T23:49:19Z  INFO    OGG-08100  EXTTRAIL added.