Re: POC: Extension for adding distributed tracing - pg_tracing
| От | Anthonin Bonnefoy |
|---|---|
| Тема | Re: POC: Extension for adding distributed tracing - pg_tracing |
| Дата | |
| Msg-id | CAO6_Xqr5cNC-fK7kX4Pt9LkYSNjuZQjDfxbm_ckypM9LD8PT1Q@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: POC: Extension for adding distributed tracing - pg_tracing (Aleksander Alekseev <aleksander@timescale.com>) |
| Ответы |
Re: POC: Extension for adding distributed tracing - pg_tracing
|
| Список | pgsql-hackers |
I've initially thought of sending the spans from PostgreSQL since this is the usual behavior of tracing libraries.
However, this created a lot potential issues:
- Protocol support and differences between trace collectors. OpenTelemetry seems to use gRPC, others are using http and those will require additional libraries (plus gRPC support in C doesn't look good) and any change in protobuf definition would require updating the extension.
- Do we send the spans within the query hooks? This means that we could block the process if the trace collector is slow to answer or we can’t connect. Sending spans from a background process sounded rather complex and resource heavy.
Moving to a pull model fixed those issues and felt more natural as this is the way PostgreSQL exposes its metrics.
Nikita,
> This patch looks very interesting, I'm working on the same subject too. But I've used
> another approach - I'm using C wrapper for C++ API library from OpenTelemetry, and
> handle span storage and output to this library. There are some nuances though, but it
> is possible. Have you tried to use OpenTelemetry APIs instead of implementing all
> functionality around spans?
I don't think that PostgreSQL accepts such kind of C++ code, not to
mention the fact that the PostgreSQL license is not necessarily
compatible with Apache 2.0 (I'm not a lawyer; this is not a legal
advice). Such a design decision will probably require using separate
compile flags since the user doesn't necessarily have a corresponding
dependency installed. Similarly to how we do with LLVM, OpenSSL, etc.
So -1 to the OpenTelemetry C++ library and +1 to the properly licensed
C implementation without 3rd party dependencies from me. Especially
considering the fact that the implementation seems to be rather
simple.
--
Best regards,
Aleksander Alekseev
В списке pgsql-hackers по дате отправления: