Symptoms

After upgrading from blackpearl 4.6.7 to 4.6.9, most of the reporting data got "wiped" from the serverlog tables. The workspace reports have no more data to display.
 

Diagnoses

After some investigations, we noticed that there were some entries "stuck" in the "Server.Log" table. There were a couple of ProocInstIDs that were "zero" ('0'). We were able to reproduce this by deleting the entire process from workspace. During the upgrade, we noticed that after the DB configuration step has been completed, that all the data is still there. Only when setup manager started the K2Server service, did the serverLog data get wiped.

How it works: Before data goes to the "ServerLog.*" tables, it gets written to the "Server.Log" table. If the K2Server has time, it should pick up these records, process it and write/delete the relevant data to/from the "ServerLog" tables.

In an ideal world, if you run a "SELECT" query on the "Server.Log" table, you should not see much data there. You might catch something in there every now and then, but the logging server should process those records relatively quick.
 

Resolution

In this case, there were a couple of entries with a procInstID of zero ('0') in the "Server.Log" table. After the upgrade, setup manager started the K2Server, the K2Server started to process the records in the "Server.Log" table and deleted the reporting data. This is "expected behavior".

If the records did not get stuck in the "Server.Log table", they would have been deleted the moment the user deleted the process from workspace. But, because they got stuck and because the K2Server only started processing the stuck records after the upgrade, this gave the impression that the upgrade wiped the reporting data from the "ServerLog.*" tables.

If you delete processes/process instances WITHOUT checking the "Delete log info" checkbox, only the process instances will get deleted and the reporting data should remain in the "ServerLog.*" tables.