jackylee-ch commented on code in PR #15814:
URL: https://github.com/apache/iceberg/pull/15814#discussion_r3014373053
##########
docs/docs/spark-ddl.md:
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@@ -326,6 +330,21 @@ ALTER TABLE prod.db.sample DROP COLUMN id;
ALTER TABLE prod.db.sample DROP COLUMN point.z;
```
+!!! warning "Hive Catalog Limitation"
+ When using a **Hive catalog**, dropping a column that is not the last
column in the table schema
+ may fail with an error from the Hive Metastore (HMS). This occurs because
HMS validates schema
+ changes by comparing column types **positionally** — dropping a middle
column shifts subsequent
+ columns, which HMS interprets as incompatible type changes
+ (`MetaStoreUtils#throwExceptionIfIncompatibleColTypeChange`).
+
+ To work around this, disable the HMS schema compatibility check by setting
+ `hive.metastore.disallow.incompatible.col.type.changes=false` in
`hive-site.xml`, or by passing
+ `--conf
spark.hadoop.hive.metastore.disallow.incompatible.col.type.changes=false` when
starting Spark.
Review Comment:
I have check remote HMS with version 3.1.3, which contains the HIVE-17832
and HIVE-17942, they still don't work. Thus, I updated the documentation as
follows.
- **Remote HMS:** Set this property in the HMS server's `hive-site.xml`.
- **Embedded HMS:** Add the equivalent property to the Hive catalog
configuration.
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