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Multiple Rollback Segments

Warning

This feature has been removed in Percona Server 5.5.11-20.2 because an equivalent variable, innodb_rollback_segments, has been implemented in the upstream version.

In Percona Server 5.1, an improvement was provided for write-intensive workloads that allowed multiple rollback segments to be used.

Percona Server, in addition to the upstream multiple rollback segment implementation, provides the additional Information Schema table: INNODB_RSEG.

INFORMATION_SCHEMA Tables

This feature provides the following table:

table INFORMATION_SCHEMA.INNODB_RSEG
Columns:
  • rseg_id – rollback segment id
  • space_id – space where the segment placed
  • zip_size – compressed page size in bytes if compressed otherwise 0
  • page_no – page number of the segment header
  • max_size – max size in pages
  • curr_size – current size in pages

This table shows information about all the rollback segments (the default segment and the extra segments).

Here is an example of output with innodb_extra_rsegments = 8

mysql> select * from information_schema.innodb_rseg;
+---------+----------+----------+---------+------------+-----------+
| rseg_id | space_id | zip_size | page_no | max_size   | curr_size |
+---------+----------+----------+---------+------------+-----------+
|       0 |        0 |        0 |       6 | 4294967294 |         1 |
|       1 |        0 |        0 |      13 | 4294967294 |         2 |
|       2 |        0 |        0 |      14 | 4294967294 |         1 |
|       3 |        0 |        0 |      15 | 4294967294 |         1 |
|       4 |        0 |        0 |      16 | 4294967294 |         1 |
|       5 |        0 |        0 |      17 | 4294967294 |         1 |
|       6 |        0 |        0 |      18 | 4294967294 |         1 |
|       7 |        0 |        0 |      19 | 4294967294 |         1 |
|       8 |        0 |        0 |      20 | 4294967294 |         1 |
+---------+----------+----------+---------+------------+-----------+
9 rows in set (0.00 sec)
This documentation is developed in Launchpad as part of the Percona Server 5.5.
If you spotted inaccuracies, errors, don't understood it or you think something is missing or should be improved, please file a bug.


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