fix(iceberg): fix select empty iceberg table (#18449)

ci/scripts/e2e-iceberg-sink-v2-test.sh

@@ -45,6 +45,7 @@ poetry run python main.py -t ./test_case/partition_upsert.toml
 poetry run python main.py -t ./test_case/range_partition_append_only.toml
 poetry run python main.py -t ./test_case/range_partition_upsert.toml
 poetry run python main.py -t ./test_case/append_only_with_checkpoint_interval.toml
+poetry run python main.py -t ./test_case/iceberg_select_empty_table.toml
 
 
 echo "--- Kill cluster"

e2e_test/iceberg/test_case/iceberg_select_empty_table.slt

@@ -0,0 +1,60 @@
+statement ok
+set sink_decouple = false;
+
+statement ok
+set streaming_parallelism=4;
+
+statement ok
+CREATE TABLE s1 (i1 int, i2 varchar, i3 varchar);
+
+statement ok
+CREATE MATERIALIZED VIEW mv1 AS SELECT * FROM s1;
+
+statement ok
+CREATE SINK sink1 AS select * from mv1 WITH (
+    connector = 'iceberg',
+    type = 'append-only',
+    force_append_only = 'true',
+    database.name = 'demo_db',
+    table.name = 't1',
+    catalog.name = 'demo',
+    catalog.type = 'storage',
+    warehouse.path = 's3a://icebergdata/demo',
+    s3.endpoint = 'http://127.0.0.1:9301',
+    s3.region = 'us-east-1',
+    s3.access.key = 'hummockadmin',
+    s3.secret.key = 'hummockadmin',
+    commit_checkpoint_interval = 1,
+    create_table_if_not_exists = 'true'
+);
+
+statement ok
+CREATE SOURCE iceberg_t1_source
+WITH (
+    connector = 'iceberg',
+    s3.endpoint = 'http://127.0.0.1:9301',
+    s3.region = 'us-east-1',
+    s3.access.key = 'hummockadmin',
+    s3.secret.key = 'hummockadmin',
+    catalog.type = 'storage',
+    warehouse.path = 's3a://icebergdata/demo',
+    database.name = 'demo_db',
+    table.name = 't1',
+);
+
+statement ok
+flush;
+
+query I
+select count(*) from iceberg_t1_source;
+----
+0
+
+statement ok
+DROP SINK sink1;
+
+statement ok
+DROP SOURCE iceberg_t1_source;
+
+statement ok
+DROP TABLE s1 cascade;

e2e_test/iceberg/test_case/iceberg_select_empty_table.toml

@@ -0,0 +1,11 @@
+init_sqls = [
+    'CREATE SCHEMA IF NOT EXISTS demo_db',
+    'DROP TABLE IF EXISTS demo_db.t1',
+]
+
+slt = 'test_case/iceberg_select_empty_table.slt'
+
+drop_sqls = [
+    'DROP TABLE IF EXISTS demo_db.t1',
+    'DROP SCHEMA IF EXISTS demo_db',
+]

src/connector/src/source/iceberg/mod.rs

@@ -206,6 +206,17 @@ impl IcebergSplitEnumerator {
             bail!("Batch parallelism is 0. Cannot split the iceberg files.");
         }
         let table = self.config.load_table_v2().await?;
+        let current_snapshot = table.metadata().current_snapshot();
+        if current_snapshot.is_none() {
+            // If there is no snapshot, we will return a mock `IcebergSplit` with empty files.
+            return Ok(vec![IcebergSplit {
+                split_id: 0,
+                snapshot_id: 0, // unused
+                table_meta: TableMetadataJsonStr::serialize(table.metadata()),
+                files: vec![],
+            }]);
+        }
+
         let snapshot_id = match time_traval_info {
             Some(IcebergTimeTravelInfo::Version(version)) => {
                 let Some(snapshot) = table.metadata().snapshot_by_id(version) else {
@@ -232,10 +243,10 @@ impl IcebergSplitEnumerator {
                     }
                 }
             }
-            None => match table.metadata().current_snapshot() {
-                Some(snapshot) => snapshot.snapshot_id(),
-                None => bail!("Cannot find the current snapshot id in the iceberg table."),
-            },
+            None => {
+                assert!(current_snapshot.is_some());
+                current_snapshot.unwrap().snapshot_id()
+            }
         };
         let mut files = vec![];