There is an issue that can cause secondary indexes on columnstore tables to become corrupted after being altered or dropped and cause additional alters on the table to crash the node. This bug impacts MemSQL 7.0 versions up to and including 7.0.14.
The fix for this bug was released in version 7.0.15 of MemSQL.
If you have not yet upgraded to MemSQL 7.0 or are already using MemSQL 7.0.15 or later, there is no action required. This does not affect MemSQL versions 6.8 or earlier.
Bug Trigger
This bug can be triggered by running an ALTER TABLE to add a secondary index to a columnstore table, truncating the table, and then restarting the node, which can cause the added secondary index to be disabled and future alters on the table to crash the node.
It can also be triggered by dropping a secondary index on a columnstore table and then adding another secondary index on the table (via ALTER TABLE), which causes the secondary indexes on the table to become corrupted after a node restart and future alters to fail.
We recommend that you upgrade to version 7.0.15 to avoid this bug, and if you cannot yet upgrade, we suggest you avoid altering or dropping secondary columnstore indexes via ALTER TABLE until you are able to upgrade.
Thank you,
MemSQL Support