I discovered that my production environment, tables.

PARTICIPATION has 1.373.344 KB with 14.848.703 rows

TASK          has 104.968 KB with 207.575 rows

TaskServiceImpl.findGroupTasks is very slow.

To resolve this issue I just created an index

CREATE NONCLUSTERED INDEX [IDX_PART_GROUP] ON [dbo].[JBPM4_PARTICIPATION]

(

    [GROUPID_] ASC

)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]

Is it normal an participation table with 15 milions of rows?

If the answer is yes, so it is better to have this index in JBPM4 script.

What type of archiving can be made to table participation?

We a using SQL Server 2005 with JBPM 4.3