oneonestar opened a new issue, #9723:
URL: https://github.com/apache/iceberg/issues/9723

   ### Query engine
   
   Spark
   
   ### Question
   
   In `metadata_log_entries` table, `latest_snapshot_id, latest_schema_id, 
latest_sequence_number` return null in some cases. Also, those values became 
null after `CREATE OR REPLACE`.
   The current implementation rely on `snapshot-log` field in metadata file, 
and `snapshot-log` got reset after after the CREATE OR REPLACE statement.
   
   Is this an intended behavior?
   Could someone provide a precise definition for `latest_snapshot_id, 
latest_schema_id, latest_sequence_number`?
   
   ```
   spark-sql> create table test.t1 (c1 integer);
   
   spark-sql> alter table test.t1 add columns (c2 string);
   
   spark-sql> SELECT * FROM test.t1.metadata_log_entries;
   2024-01-22 18:51:41.331      
hdfs://hadoop/metadata/00000-d1ad9769-3bf3-497d-a86e-20f71d2700f7.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:51:41.593      
hdfs://hadoop/metadata/00001-9eb3275c-f53d-4e24-bc23-fdcadae28d92.metadata.json 
NULL    NULL    NULL
   
   spark-sql> insert into test.t1 values (1, 'a');
   
   spark-sql> SELECT * FROM test.t1.metadata_log_entries;
   2024-01-22 18:51:41.331      
hdfs://hadoop/metadata/00000-d1ad9769-3bf3-497d-a86e-20f71d2700f7.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:51:41.593      
hdfs://hadoop/metadata/00001-9eb3275c-f53d-4e24-bc23-fdcadae28d92.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:51:47.538      
hdfs://hadoop/metadata/00002-ec3f0aa6-7dae-4c45-90ad-13839eefbd54.metadata.json 
1836642618692808023     1       0
   
   spark-sql> delete from test.t1 where c1 = 1;
   
   spark-sql> SELECT * FROM test.t1.metadata_log_entries;
   2024-01-22 18:51:41.331      
hdfs://hadoop/metadata/00000-d1ad9769-3bf3-497d-a86e-20f71d2700f7.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:51:41.593      
hdfs://hadoop/metadata/00001-9eb3275c-f53d-4e24-bc23-fdcadae28d92.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:51:47.538      
hdfs://hadoop/metadata/00002-ec3f0aa6-7dae-4c45-90ad-13839eefbd54.metadata.json 
1836642618692808023     1       0
   2024-01-22 18:51:52.6        
hdfs://hadoop/metadata/00003-806771f6-e7f1-44f5-ac80-350f2c084505.metadata.json 
8876099574020403871     1       0
   
   spark-sql> CALL local.system.rewrite_data_files('test.t1');
   
   spark-sql> SELECT * FROM test.t1.metadata_log_entries;
   2024-01-22 18:51:41.331      
hdfs://hadoop/metadata/00000-d1ad9769-3bf3-497d-a86e-20f71d2700f7.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:51:41.593      
hdfs://hadoop/metadata/00001-9eb3275c-f53d-4e24-bc23-fdcadae28d92.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:51:47.538      
hdfs://hadoop/metadata/00002-ec3f0aa6-7dae-4c45-90ad-13839eefbd54.metadata.json 
1836642618692808023     1       0
   2024-01-22 18:51:52.6        
hdfs://hadoop/metadata/00003-806771f6-e7f1-44f5-ac80-350f2c084505.metadata.json 
8876099574020403871     1       0
   
   spark-sql> create or replace table test.t1 (c3 integer);
   
   spark-sql> SELECT * FROM test.t1.metadata_log_entries;
   2024-01-22 18:51:41.331      
hdfs://hadoop/metadata/00000-d1ad9769-3bf3-497d-a86e-20f71d2700f7.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:51:41.593      
hdfs://hadoop/metadata/00001-9eb3275c-f53d-4e24-bc23-fdcadae28d92.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:51:47.538      
hdfs://hadoop/metadata/00002-ec3f0aa6-7dae-4c45-90ad-13839eefbd54.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:51:52.6        
hdfs://hadoop/metadata/00003-806771f6-e7f1-44f5-ac80-350f2c084505.metadata.json 
NULL    NULL    NULL
   2024-01-22 18:52:01.749      
hdfs://hadoop/metadata/00004-d9c74f49-37c8-4463-8565-7b31660723e2.metadata.json 
NULL    NULL    NULL
   ```


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