amogh-jahagirdar opened a new issue, #9555:
URL: https://github.com/apache/iceberg/issues/9555
### Apache Iceberg version
1.4.3 (latest release)
### Query engine
Spark
### Please describe the bug 🐞
Reproduction:
Here's a simple unit test (can copy/paste this into `TestMerge`)
```
@Test
public void testMergeIntoTsIssue() {
createAndInitTable(
"id INT, ts TIMESTAMP",
"{ \"id\": 1, \"ts\": \"2000-01-01 00:00:00\" }\n" + "{ \"id\": 6,
\"ts\": null }");
createOrReplaceView(
"source",
"id INT NOT NULL, dep STRING",
"{ \"id\": 1, \"ts\": \"2000-01-01 00:00:00\" }\n");
sql(
"MERGE INTO %s t USING source s "
+ "ON t.id == s.id "
+ "WHEN MATCHED THEN "
+ " UPDATE SET id=123, ts=current_timestamp()",
commitTarget());
sql("SELECT * FROM %s", commitTarget());
}
```
In short:
1.) create a table
2.) insert some records where at least one of the records has a NULL column
value.
3.) MERGE into the table with an update on matched records and set the
column with the null value
Expected:
Record 1: id=123, ts=current_timestamp()
Record 2: id=6, ts=null
However, in Spark 3.4 we get
Record 1:id=123, ts=current_timestamp()
Record 2: id=6, ts=01-01-1970 00:00:000 (basically Unix epoch. in practice
it's timestamp with tz so it'll appear to your timezone)
I've done some debugging and what's happening is that the schema for the
`SparkWrite` in 3.4 is treating all the fields as required, leading to the
default behavior.
The reason why it's treating it as required is because the Spark expression
`nullability` is that the attributes for the fields
https://github.com/apache/iceberg/blob/main/spark/v3.4/spark-extensions/src/main/scala/org/apache/spark/sql/catalyst/analysis/RewriteMergeIntoTable.scala#L182
aren't being passed to the merge output schema during planning. This
nullability needs to be passed correctly so that the null values in the
non-matched cases get written correctly.
I'm currently looking into this, but creating this issue for tracking and
awareness.
Important Note:
Spark 3.3 and Spark 3.5 do not have this bug based on my testing.
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