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new 6dc6308cc6 Docs: Add an example of Spark SQL to set identifier fields
(#6444)
6dc6308cc6 is described below
commit 6dc6308cc6ba0f189b83cba889ee7134e56ec002
Author: Kunni <[email protected]>
AuthorDate: Sat Dec 17 04:34:31 2022 +0800
Docs: Add an example of Spark SQL to set identifier fields (#6444)
---
docs/spark-ddl.md | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/docs/spark-ddl.md b/docs/spark-ddl.md
index d5e89b332b..6347ae5481 100644
--- a/docs/spark-ddl.md
+++ b/docs/spark-ddl.md
@@ -446,3 +446,29 @@ ALTER TABLE prod.db.sample WRITE DISTRIBUTED BY PARTITION
```sql
ALTER TABLE prod.db.sample WRITE DISTRIBUTED BY PARTITION LOCALLY ORDERED BY
category, id
```
+
+### `ALTER TABLE ... SET IDENTIFIER FIELDS`
+
+Iceberg supports setting identifier fields to a spec using `SET IDENTIFIER
FIELDS`:
+
+```sql
+ALTER TABLE prod.db.sample SET IDENTIFIER FIELDS id
+-- single column
+ALTER TABLE prod.db.sample SET IDENTIFIER FIELDS id, data
+-- multiple columns
+```
+
+identifier fields must be `NOT NULL`, The later `ALTER` statement will
overwrite the previous setting.
+
+### `ALTER TABLE ... DROP IDENTIFIER FIELDS`
+
+Identifier fields can be removed using `DROP IDENTIFIER FIELDS`:
+
+```sql
+ALTER TABLE prod.db.sample DROP IDENTIFIER FIELDS id
+-- single column
+ALTER TABLE prod.db.sample DROP IDENTIFIER FIELDS id, data
+-- multiple columns
+```
+
+Note that although the identifier is removed, the column will still exist in
the table schema.
\ No newline at end of file
