Upgrade from 4.0 to 4.1 may need to consider new fate table.

Accumulo checks if any fate operation are present when upgrading and will refuse to upgrade if any are present. In Accumulo 4.0 a new fate table was introduced. Prior to Accumulo 4.0 fate operations were only stored in zookeeper. After 4.0 fate operations are stored in zookeeper and the metadata table. Eventually the upgrade code for 4.1 may need to check for fate operations in both of these places. Currently the following code checks for fate operations in zookeeper only.

https://github.com/apache/accumulo/blob/f6909cd7067cad575e70893f3c1d5f4c99cc5676/server/manager/src/main/java/org/apache/accumulo/manager/upgrade/UpgradeCoordinator.java#L313

This issue covers a potential problem with unreleased code and therefore its possible it may become irrelevant depending on changes and could be closed if that happens. Opening an issue now so that its not forgotten for 4.1 upgrade.

Start in server/manager/src/main/java/org/apache/accumulo/manager/upgrade/UpgradeCoordinator.java around line 313, where upgrade checks for fate operations in ZooKeeper. Compare that check with the 4.0 fate-table storage described in the issue, then determine whether the 4.1 upgrade must inspect both locations. Done when the upgrade behavior for existing fate operations is confirmed or corrected.

Written by the indexing model from the issue text.