topic transactions example

Author: vgvoleg

examples/topic/topic_transactions_example.py

@@ -0,0 +1,27 @@
+import ydb
+
+
+def writer_example(driver: ydb.Driver, topic: str):
+    session_pool = ydb.QuerySessionPool(driver)
+
+    def callee(tx: ydb.QueryTxContext):
+        tx_writer: ydb.TopicTxWriter = driver.topic_client.tx_writer(tx, topic)
+
+        with tx.execute(query="select 1") as result_sets:
+            messages = [result_set.rows[0] for result_set in result_sets]
+
+        tx_writer.write(messages)
+
+    session_pool.retry_tx_sync(callee)
+
+
+def reader_example(driver: ydb.Driver, reader: ydb.TopicReader):
+    session_pool = ydb.QuerySessionPool(driver)
+
+    def callee(tx: ydb.QueryTxContext):
+        batch = reader.receive_batch_with_tx(tx)
+
+        with tx.execute(query="INSERT INTO max_values(val) VALUES ($val)", parameters={"$val": max(batch)}) as _:
+            pass
+
+    session_pool.retry_tx_sync(callee)