KB-1419 KDB numbering goes negative

Symptom

KDB file numbering for one or more engines moves into the negatives. This may manifest in:

• the actual .kdb files on disk
• the checkpointing messages in the corresponding gw_ log
• the DB ID referenced in the corresponding db_ log

For example, if the process execution01 engine is the one in question, you may notice the following:

• A negative .kdb file in <APPIAN_HOME>/server/process/exec/01/gw1/: pe-2147483646.kdb.
• A reference in the gw_PX001 log: [PX001] INFO .a.gw.ssa "Server switchover to database ID -2147483646".
• A reference in the db_PX001 log: [PX001] {pe-2147483646.kdb ,4405}.

Cause

This issue can occur after improperly resetting a particular engine's KDBs or if extraneous KDB files are manually introduced.

Action

1. Shut down the engine with the negative KDB numbering.
2. Rename any negative KDBs to positive numbers, ensuring that the most recent KDB has the highest number.
3. Start the engine and confirm that KDB numbering is positive once again.

Warning: Renaming .kdb files is not supported beyond what is documented in this article.

Affected Versions

Last Reviewed: November 2017