Fix empty table insert requirement

src/include/rest_catalog/objects/assert_ref_snapshot_id.hpp

@@ -30,6 +30,7 @@ class AssertRefSnapshotId {
 	TableRequirementType type;
 	string ref;
 	int64_t snapshot_id;
+	bool has_snapshot_id = false;
 };
 
 } // namespace rest_api_objects

src/rest_catalog/objects/assert_ref_snapshot_id.cpp

@@ -50,10 +50,14 @@ string AssertRefSnapshotId::TryFromJSON(yyjson_val *obj) {
 	if (!snapshot_id_val) {
 		return "AssertRefSnapshotId required property 'snapshot-id' is missing";
 	} else {
-		if (yyjson_is_sint(snapshot_id_val)) {
+		if (yyjson_is_null(snapshot_id_val)) {
+			has_snapshot_id = false;
+		} else if (yyjson_is_sint(snapshot_id_val)) {
 			snapshot_id = yyjson_get_sint(snapshot_id_val);
+			has_snapshot_id = true;
 		} else if (yyjson_is_uint(snapshot_id_val)) {
 			snapshot_id = yyjson_get_uint(snapshot_id_val);
+			has_snapshot_id = true;
 		} else {
 			return StringUtil::Format(
 			    "AssertRefSnapshotId property 'snapshot_id' is not of type 'integer', found '%s' instead",

src/storage/irc_transaction.cpp

@@ -47,7 +47,11 @@ void CommitTableToJSON(yyjson_mut_doc *doc, yyjson_mut_val *root_object,
 			auto requirement_json = yyjson_mut_arr_add_obj(doc, requirements_array);
 			yyjson_mut_obj_add_strcpy(doc, requirement_json, "type", assert_ref_snapshot_id.type.value.c_str());
 			yyjson_mut_obj_add_strcpy(doc, requirement_json, "ref", assert_ref_snapshot_id.ref.c_str());
-			yyjson_mut_obj_add_uint(doc, requirement_json, "snapshot-id", assert_ref_snapshot_id.snapshot_id);
+			if (assert_ref_snapshot_id.has_snapshot_id) {
+				yyjson_mut_obj_add_uint(doc, requirement_json, "snapshot-id", assert_ref_snapshot_id.snapshot_id);
+			} else {
+				yyjson_mut_obj_add_null(doc, requirement_json, "snapshot-id");
+			}
 		} else if (requirement.has_assert_create) {
 			auto &assert_create = requirement.assert_create;
 			auto requirement_json = yyjson_mut_arr_add_obj(doc, requirements_array);
@@ -230,6 +234,18 @@ static rest_api_objects::TableRequirement CreateAssertRefSnapshotIdRequirement(I
 	auto &res = req.assert_ref_snapshot_id;
 	res.ref = "main";
 	res.snapshot_id = old_snapshot.snapshot_id;
+	res.has_snapshot_id = true;
+	res.type.value = "assert-ref-snapshot-id";
+	return req;
+}
+
+static rest_api_objects::TableRequirement CreateAssertNoSnapshotRequirement() {
+	rest_api_objects::TableRequirement req;
+	req.has_assert_ref_snapshot_id = true;
+
+	auto &res = req.assert_ref_snapshot_id;
+	res.ref = "main";
+	res.has_snapshot_id = false;
 	res.type.value = "assert-ref-snapshot-id";
 	return req;
 }
@@ -307,6 +323,10 @@ TableTransactionInfo IRCTransaction::GetTransactionRequest(ClientContext &contex
 			//! If any changes were made to the state of the table, we should assert that our parent snapshot has
 			//! not changed. We don't want to change the table location if someone has added a snapshot
 			commit_state.table_change.requirements.push_back(CreateAssertRefSnapshotIdRequirement(*current_snapshot));
+		} else if (!info.has_assert_create) {
+			//! If the table had no snapshots and isn't created by this transaction, we should assert that no snapshot
+			//! has been added in the meantime
+			commit_state.table_change.requirements.push_back(CreateAssertNoSnapshotRequirement());
 		}
 
 		transaction.table_changes.push_back(std::move(table_change));

test/sql/local/irc/insert/test_concurrent_insert_new_table.test

@@ -0,0 +1,73 @@
+# name: test/sql/local/irc/insert/test_concurrent_insert_new_table.test
+# description: Test concurrent inserts to a newly created table with no snapshots
+# group: [insert]
+
+require-env ICEBERG_SERVER_AVAILABLE
+
+require avro
+
+require parquet
+
+require iceberg
+
+require httpfs
+
+# Do not ignore 'HTTP' error messages!
+set ignore_error_messages
+
+statement ok
+CREATE SECRET (
+    TYPE S3,
+    KEY_ID 'admin',
+    SECRET 'password',
+    ENDPOINT '127.0.0.1:9000',
+    URL_STYLE 'path',
+    USE_SSL 0
+);
+
+statement ok
+ATTACH '' AS my_datalake (
+    TYPE ICEBERG,
+    CLIENT_ID 'admin',
+    CLIENT_SECRET 'password',
+    ENDPOINT 'http://127.0.0.1:8181'
+);
+
+statement ok
+DROP TABLE IF EXISTS my_datalake.default.concurrent_new_table_test;
+
+statement ok
+CREATE TABLE my_datalake.default.concurrent_new_table_test (id INTEGER, name VARCHAR);
+
+# con1 starts a transaction and inserts
+statement ok con1
+begin
+
+statement ok con1
+INSERT INTO my_datalake.default.concurrent_new_table_test VALUES (1, 'con1');
+
+# con2 starts a transaction and inserts
+statement ok con2
+begin
+
+statement ok con2
+INSERT INTO my_datalake.default.concurrent_new_table_test VALUES (2, 'con2');
+
+# con2 commits first
+statement ok con2
+commit
+
+# con1 should fail because con2 already added a snapshot
+statement error con1
+commit
+----
+<REGEX>:.*Requirement failed: branch main was created concurrently.*
+
+# only con2's data is in the table
+query II
+SELECT * FROM my_datalake.default.concurrent_new_table_test ORDER BY id;
+----
+2	con2
+
+statement ok
+DROP TABLE my_datalake.default.concurrent_new_table_test;