langchain/vectorstores/pgvector.py/PGVector/create_vector_extension
class PGVector:    def create_vector_extension(self) -> None:
        try:
            with Session(self._conn) as session:
                statement = sqlalchemy.text("CREATE EXTENSION IF NOT EXISTS vector")
                session.execute(statement)
                session.commit()
        except Exception as e:
            self.logger.exception(e)