docs: clarify Python string values are bytes

Verified the new examples against timeplus/timeplusd:3.2.2 and :3.2.7.
Sink-side string columns arrive as Python `bytes`, not `str`, since
v3.2.2 (proton-enterprise commit 43c46c5, #11788). The original
`py_metric_sink` and `post_event` examples needed `.decode()` to run;
add the calls and a one-paragraph note linking to the Python UDF data
type mapping. Also bump the product-version note to 3.2.2+ so it
matches the floor where every documented setting and global is
present.

Holding merge pending the contract question in
proton-enterprise#12067.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: yokofly

docs/shared/python-external-stream-write.md

@@ -2,14 +2,16 @@
 
 The write function is invoked once per chunk, not once per row. Its arguments are **column-oriented**: one Python list per output column, in declared order, all of equal length. Iterate with `zip` to recover row tuples.
 
+Column values follow the same Python type mapping as [Python UDF](/py-udf#data-type-mapping). One detail worth highlighting for sinks: a `string` (or `fixed_string`) column arrives as Python `bytes`, not `str`. Decode with `.decode()` (UTF-8) before passing values into APIs that require text.
+
 ### Sink basics
 
 ```sql
 CREATE EXTERNAL STREAM py_metric_sink (host string, value float32)
 AS $$
 def py_metric_sink(host, value):
     for h, v in zip(host, value):
-        print(f"{h}={v}")
+        print(f"{h.decode()}={v}")
 $$
 SETTINGS type = 'python';
 ```
@@ -20,7 +22,7 @@ Insert a few rows:
 INSERT INTO py_metric_sink (host, value) VALUES ('a', 1.0), ('b', 2.0);
 ```
 
-Behind the scenes Timeplus calls `py_metric_sink(['a', 'b'], [1.0, 2.0])` — one call carrying both rows. A larger INSERT or a downstream query that delivers many chunks results in one call per chunk.
+Behind the scenes Timeplus calls `py_metric_sink([b'a', b'b'], [1.0, 2.0])` — one call carrying both rows, with the `string` column delivered as `bytes`. A larger INSERT or a downstream query that delivers many chunks results in one call per chunk.
 
 If `write_function_name` is omitted Timeplus uses `read_function_name` (which itself defaults to the stream name), so the Python function above only needs to be named once.
 
@@ -33,7 +35,7 @@ CREATE EXTERNAL STREAM py_alert_sink (host string, value float32)
 AS $$
 def py_alert_sink(host, value):
     for h, v in zip(host, value):
-        notify(h, v)   # your notifier
+        notify(h.decode(), v)   # your notifier
 $$
 SETTINGS type = 'python';
 
@@ -61,9 +63,10 @@ def close_client():
 
 def post_event(event_id, body):
     for eid, b in zip(event_id, body):
+        payload = {"id": eid.decode(), "body": b.decode()}
         req = urllib.request.Request(
             builtins._tp_webhook,
-            data=json.dumps({"id": eid, "body": b}).encode(),
+            data=json.dumps(payload).encode(),
             headers={"Content-Type": "application/json"},
             method="POST",
         )

docs/shared/python-external-stream.md

@@ -1,6 +1,6 @@
 ## Overview
 
-Python External Stream lets you read from and write to arbitrary sources by embedding a Python body directly in the DDL. It is available in **Timeplus Enterprise 3.2+**.
+Python External Stream lets you read from and write to arbitrary sources by embedding a Python body directly in the DDL. It is available in **Timeplus Enterprise 3.2.2+**.
 
 Unlike the Kafka, Pulsar, and NATS JetStream external streams — which speak a specific wire protocol — a Python External Stream is a generic escape hatch: you bring the protocol, the client library, and the logic. Timeplus calls your functions inside the embedded CPython runtime. When reading, return values become row batches; when writing, the sink function receives column batches. The same DDL object can serve as both a source (via `read_function_name`) and a sink (via `write_function_name`).
 

docs/sql-create-external-stream.md

@@ -73,7 +73,7 @@ SETTINGS
     mode = 'auto'                             -- 'auto' (default), 'streaming', or 'batch'
 ```
 
-Available in **Timeplus Enterprise 3.2+**.
+Available in **Timeplus Enterprise 3.2.2+**.
 
 Please check the [Python External Stream Source](/python-external-stream-source) for read-side settings, generator/batch sources, and lifecycle hooks, and the [Python External Stream Sink](/python-external-stream-sink) for write-side semantics, materialized-view sinks, and custom-protocol examples.