The INNODB_UNDO_LOGS are a Percona enhancement, introduced in version MariaDB 5.5.27 and removed in 10.0.
The Information Schema INNODB_UNDO_LOGS table is a Percona enchancement, and is only available for XtraDB, not InnoDB (see XtraDB and InnoDB). It contains information about the the InnoDB undo log, with each record being an undo log segment. It was removed in MariaDB 10.0.
It has the following columns:
| Column | Description |
|---|---|
TRX_ID |
Unique transaction ID number, matching the value from the information_schema.INNODB_TRX table. |
RSEG_ID |
Rollback segment ID, matching the value from the information_schema.INNODB_RSEG table. |
USEG_ID |
Undo segment ID. |
SEGMENT_TYPE |
Indicates the operation type, for example INSERT or UPDATE. |
STATE |
Segment state; one of ACTIVE (contains active transaction undo log), CACHED, TO_FREE (insert undo segment can be freed), TO_PURGE (update undo segment won't be re-used and can be purged when all undo data is removed) or PREPARED (segment of a prepared transaction). |
SIZE |
Size in pages of the segment. |
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Licensed under the Creative Commons Attribution 3.0 Unported License and the GNU Free Documentation License.
https://mariadb.com/kb/en/information-schema-innodb_undo_logs-table/