Checking Compatibility of Column Changes

A default configuration change can cause applications that change column types to fail.

Before Upgrade to CDP

In HDP 2.x hive.metastore.disallow.incompatible.col.type.changes is false by default to allow changes to incompatible column types. For example, you can change a STRING column to a column of an incompatible type, such as MAP<STRING, STRING>. No error occurs.

After Upgrade to CDP

In CDP, hive.metastore.disallow.incompatible.col.type.changes is true by default. Hive prevents changes to incompatible column types. Compatible column type changes, such as INT, STRING, BIGINT, are not blocked.

Action Required

Change applications to disallow incompatible column type changes to prevent possible data corruption. Check ALTER TABLE statements and change those that would fail due to incompatible column types.