How do you use pgvector with asyncpg or asyncio in Python?

# pip install asyncpg pgvector

import asyncio
import asyncpg
from pgvector.asyncpg import register_vector
from openai import AsyncOpenAI

async def main():
    # Connect with asyncpg
    conn = await asyncpg.connect(
        "postgresql://user:pass@localhost/mydb"
    )
    # Register the vector codec (required for asyncpg)
    await register_vector(conn)

    # Create schema
    await conn.execute("""
        CREATE TABLE IF NOT EXISTS documents (
            id        BIGSERIAL PRIMARY KEY,
            content   TEXT,
            embedding VECTOR(1536)
        )
    """)

    # Generate and insert embedding
    client = AsyncOpenAI()
    text = "pgvector is a PostgreSQL extension"
    response = await client.embeddings.create(
        model="text-embedding-3-small", input=text
    )
    embedding = response.data[0].embedding

    await conn.execute(
        "INSERT INTO documents (content, embedding) VALUES ($1, $2)",
        text, embedding
    )

    # Query: async KNN search
    query_text = "vector search in PostgreSQL"
    q_emb = (await client.embeddings.create(
        model="text-embedding-3-small", input=query_text
    )).data[0].embedding

    rows = await conn.fetch(
        "SELECT id, content, embedding <=> $1 AS dist"
        " FROM documents ORDER BY dist LIMIT 5",
        q_emb
    )
    for row in rows:
        print(f"dist={row['dist']:.4f}: {row['content']}")

    await conn.close()

asyncio.run(main())

# For connection pooling with FastAPI:
# async with asyncpg.create_pool(dsn) as pool:
#     async with pool.acquire() as conn:
#         await register_vector(conn)
#         rows = await conn.fetch(...)