[DOC] INNODB_RSEG/XTRADB_RSEG documentation issues

[Przemek]

In:
http://www.percona.com/doc/percona-server/5.5/scalability/innodb_extra_rseg.html#INNODB_RSEG

There is example innodb_extra_rsegments variable, which exists only in PS 5.1. Since MySQL/PS 5.5 there is a new variable:
http://dev.mysql.com/doc/refman/5.5/en/innodb-parameters.html#sysvar_innodb_rollback_segments
However, it can only limit the number of rollback segments used within a transaction, but it cannot limit physically available segments (128).

mysql [localhost] {msandbox} ((none)) > select @@version;
+----------------+
| @@version |
+----------------+
| 5.5.34-rel32.0 |
+----------------+

mysql [localhost] {msandbox} ((none)) > select count(*) from information_schema.innodb_rseg;
+----------+
| count(*) |
+----------+
| 128 |
+----------+

For Percona Server 5.6, the documentation:
http://www.percona.com/doc/percona-server/5.6/diagnostics/misc_info_schema_tables.html
also has this wrong example with innodb_extra_rsegments variable.
Also, in 5.6 case, it is possible to initialize innodb system tablespace with lower number of rollback segments by using one of these variables before InnoDB table space is created:
http://dev.mysql.com/doc/refman/5.6/en/innodb-parameters.html#sysvar_innodb_rollback_segments
http://dev.mysql.com/doc/refman/5.6/en/innodb-parameters.html#sysvar_innodb_undo_logs

But then, if Innodb_available_undo_logs is lower then 128, querying the information_schema.XTRADB_RSEG leads to server crash, see lp:1260259.

And the example select in http://www.percona.com/doc/percona-server/5.6/diagnostics/misc_info_schema_tables.html#XTRADB_RSEG shows information_schema.innodb_rseg instead of information_schema.xtradb_rseg.

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-1456