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 (found in <APPIAN_HOME>/server/<ENGINE_NAME>/gw1/)
• the checkpointing messages in the corresponding gw_ log (found in <APPIAN_HOME>/logs/)
• the DB ID referenced db_ log (found in <APPIAN_HOME>/logs/)

For example, if the process execution01 engine is the engine in question, you will notice a negative .kdb file in <APPIAN_HOME>/server/process/exec/01/gw1/:

pe-2147483646.kdb

The gw_PX001 log will show something like this:

[PX001] INFO .a.gw.ssa "Server switchover to database ID -2147483646"

The db_PX001 log will show something like this:

[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 the negative KDB to a positive numbers, ensuring that the most recent KDB has the highest number.

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

Affected Versions

Last Reviewed: November 2017