chore(docs): Update readme on how to convert sync to async

README.rst

@@ -174,8 +174,81 @@ See the full `Checkpoint`_ tutorial.
 
 .. _`Checkpoint`: https://github.com/googleapis/langchain-google-cloud-sql-pg-python/blob/main/docs/langgraph_checkpoint.ipynb
 
+Example Usage
+-------------
+
+Code examples can be found in the `samples/`_ folder.
+
+.. _samples/: https://github.com/googleapis/langchain-google-cloud-sql-pg-python/tree/main/samples
+
+Converting between Sync & Async Usage
+-------------------------------------
+
+Async functionality improves the speed and efficiency of database connections through concurrency,
+which is key for providing enterprise quality performance and scaling in GenAI applications. This
+package uses a native async Postgres driver, `asyncpg`_, to optimize Python's async functionality.
+
+LangChain supports `async programming`_, since LLM based application utilize many I/O-bound operations,
+such as making API calls to language models, databases, or other services. All components should provide
+both async and sync versions of all methods.
+
+`asyncio`_ is a Python library used for concurrent programming and is used as the foundation for multiple
+Python asynchronous frameworks. asyncio uses `async` / `await` syntax to achieve concurrency for
+non-blocking I/O-bound tasks using one thread with cooperative multitasking instead of multi-threading.
+
+.. _`async programming`: https://python.langchain.com/docs/concepts/async/
+.. _`asyncio`: https://docs.python.org/3/library/asyncio.html
+.. _`asyncpg`: https://github.com/MagicStack/asyncpg
+
+Converting Sync to Async
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Update sync methods to `await` async methods
+
+.. code:: python
+
+   engine = await PostgresEngine.afrom_instance("project-id", "region", "my-instance", "my-database")
+   await engine.ainit_vectorstore_table(table_name="my-table", vector_size=768)
+   vectorstore = await PostgresVectorStore.create(
+      engine,
+      table_name="my-table",
+      embedding_service=VertexAIEmbeddings(model_name="textembedding-gecko@003")
+   )
+
+Run the code: notebooks
+^^^^^^^^^^^^^^^^^^^^^^^
+
+ipython and jupyter notebooks support the use of the `await` keyword without any additional setup
+
+Run the code: FastAPI
+^^^^^^^^^^^^^^^^^^^^^
+
+Update routes to use `async def`.
+
+.. code:: python
+
+   @app.get("/invoke/")
+   async def invoke(query: str):
+      return await retriever.ainvoke(query)
+
+
+Run the code: Local python file
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+It is recommend to create a top-level async method definition: `async def` to wrap multiple async methods.
+Then use `asyncio.run()` to run the the top-level entrypoint, e.g. "main()"
+
+.. code:: python
+
+   async def main():
+      response = await retriever.ainvoke(query)
+      print(response)
+
+   asyncio.run(main())
+
+
 Contributions
-~~~~~~~~~~~~~
+-------------
 
 Contributions to this library are always welcome and highly encouraged.
 
@@ -188,7 +261,14 @@ information.
 .. _`CONTRIBUTING`: https://github.com/googleapis/langchain-google-cloud-sql-pg-python/tree/main/CONTRIBUTING.md
 .. _`Code of Conduct`: https://github.com/googleapis/langchain-google-cloud-sql-pg-python/tree/main/CODE_OF_CONDUCT.md
 
+License
+-------
+
+Apache 2.0 - See
+`LICENSE <https://github.com/googleapis/langchain-google-cloud-sql-pg-python/tree/main/LICENSE>`_
+for more information.
+
 Disclaimer
-~~~~~~~~~~~
+----------
 
 This is not an officially supported Google product.