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Proposal for vector db semantic convention #1231

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@ezimuel ezimuel commented Jul 10, 2024

This is a proposal for vector db semantic convention (see #936). I tried to expand the db semantic convention adding some db.vector attributes. I tried to focus on the basic needs of a general purpose vector database.

I proposed the following experimental attributes (updated with the feedbacks in this PR):

db.search.similarity_metric: specify the metric used in similarity search (e.g. cosine)
db.record.id: the ID of the record (e.g. the ID of the vector)
db.vector.field_name: the name field of the vector embedding
db.vector.dimension_count: the dimension of the vector (e.g. 1536)
db.query.limit: the number of vectors returned by a query (e.g. top-k)

The operations performed in a vector db, such as insert, update, search and delete can be performed using the existing db.operation.name attribute.

Regarding the similarity search we can use the db.query attributes, such as db.query.parameter.<key>.

@ezimuel ezimuel requested review from a team July 10, 2024 15:14
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@karthikscale3
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karthikscale3 commented Jul 17, 2024

Thanks for creating this PR. A few additional attributes which we instrument today with our SDK that we have found useful are the following:

db.index
db.namespace
db.collection.name
db.top_k
db.query

Thoughts on the ones listed above? cc @lmolkova

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ezimuel commented Jul 17, 2024

@karthikscale3 regarding the attributes that you proposed, some already exists:

  • db.index can be represented using db.operation.name = index;
  • db.namespace already exists;
  • db.collection.name already exists;
  • db.query can be represented using db.query.text and also db.query.parameter;

The top_k proposal I think it's a good idea:

  • db.vector.query.top_k to represent the k most similar vectors returned by a similarity serach;

Moreover, I found very interesting the proposal of OpenLLMetry project especially the part regarding the attributes for vector db, here:

 # Vector DB
 VECTOR_DB_VENDOR = "db.system"
 VECTOR_DB_OPERATION = "db.operation"
 VECTOR_DB_QUERY_TOP_K = "db.vector.query.top_k"

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ezimuel commented Jul 17, 2024

@lmolkova I applied all the feedbacks, thanks for the review. @karthikscale3 I added the top_k attribute, thanks.

Summary of the changes:

  • removed vector in db.system;
  • removed the db.vector.embeddings;
  • renamed db.vector.dimension in db.vector.dimension_count;
  • added the db.vector.query.top_k as suggested by @karthikscale3;
  • removed the allow_custom_values: true in db.yaml, see last commit;

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@karthikscale3 regarding the attributes that you proposed, some already exists:

  • db.index can be represented using db.operation.name = index;
  • db.namespace already exists;
  • db.collection.name already exists;
  • db.query can be represented using db.query.text and also db.query.parameter;

The top_k proposal I think it's a good idea:

  • db.vector.query.top_k to represent the k most similar vectors returned by a similarity serach;

Moreover, I found very interesting the proposal of OpenLLMetry project especially the part regarding the attributes for vector db, here:

 # Vector DB
 VECTOR_DB_VENDOR = "db.system"
 VECTOR_DB_OPERATION = "db.operation"
 VECTOR_DB_QUERY_TOP_K = "db.vector.query.top_k"

Yea that sounds good! And yes, my intention was to reuse the existing ones. Wasn't sure if we needed them redefined for the sake of vector dbs or not. But sounds like its unnecessary.

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@lmolkova I applied all the feedbacks, thanks for the review. @karthikscale3 I added the top_k attribute, thanks.

Summary of the changes:

  • removed vector in db.system;
  • removed the db.vector.embeddings;
  • renamed db.vector.dimension in db.vector.dimension_count;
  • added the db.vector.query.top_k as suggested by @karthikscale3;
  • removed the allow_custom_values: true in db.yaml, see last commit;

Thank you! From my side, everything looks good. We discussed this PR in today's working group call and @nirga wanted to take a deeper look at it once again.

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ezimuel commented Jul 18, 2024

I fixed the merge issues. Thanks @trask

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Thanks, that's a great start! I wonder if we want to add specific spans that use these attributes in this PR as well?

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ezimuel commented Jul 20, 2024

@nirga can you give me an example of specific span? FYI, I'm going offline and I'll come back August 4 for further discussion.

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nirga commented Jul 20, 2024

Sorry, nvm I think this is already covered as part of the DB semconv

@@ -199,6 +200,28 @@ This group defines attributes for Elasticsearch.

**[8]:** Many Elasticsearch url paths allow dynamic values. These SHOULD be recorded in span attributes in the format `db.elasticsearch.path_parts.<key>`, where `<key>` is the url path part name. The implementation SHOULD reference the [elasticsearch schema](https://raw.githubusercontent.com/elastic/elasticsearch-specification/main/output/schema/schema.json) in order to map the path part values to their names.

## Db Vector Attributes
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nit: Vector Database Attributes

@maryliag
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@ezimuel looks like you missed some of the changes you marked as resolved:

  • rename db.vector.dimension to db.vector.dimension_count: it is still showing db.vector.dimension
  • rename db.vector.similarity to db.vector.search.similarity_metric: it is still showing db.vector.similarity

brief: >
The model used for the embedding.
examples: 'text-embedding-3-small'
- id: query.top_k
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I think we should come up with a more common attribute not specific to vector dbs.
Many databases allow to limit number of returned rows:

Suggesting db.query.max_returned_items. The actual returned count could be even better - db.query.item_count could mean items inserted or returned depending on the operation.

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@lmolkova I see the similarity here but I think the db.vector.query.top-k is more specific from a semantic point of view and more related to vectors, since it specifies the top k results in order, starting from the most similar. In semantic search we have this similarity value that is always present in any result that we don't have in standard database. The limit parameter of SQL returns the first k results but not in order, it depends on how you build the query (e.g. using ORDER BY).
I personally think we should keep db.vector.query.top-k and potentially add a db.query.limit (or db.query.max_returned_items as you suggested) in a separate PR.

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Out of the few dbs I checked, they use limit in vector search

So we're saying that DB instrumentations will need to detect if query is related to vector search or not and depending on this populate top-k or limit. That's difficult or impossible, but most importantly inconsistent and depends on instrumentation capabilities.

I.e. instrumentations that don't have vector-db specifics and those that do will use different attributes for the same thing.

So, I'd still prefer db.query.limit or something similar (and it should be under the same condition as db.query.text - we cannot require instrumentations to do query parsing)

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@lmolkova do you agree that top-k and limit are two different concepts, based on my previous comment? If they are I think we cannot use a single attribute (e.g. db.query.limit) to manage both.

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@lmolkova just a reminder for this, thanks.

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@ezimuel I see that databases use both terms to describe the same thing (see my comment above).

Let's say you have a postgres query like SELECT * FROM items ORDER BY embedding <-> '[3,1,2]' LIMIT 5; - the general-purpose DB instrumentation can report limit. If you make it understand vector search syntax, it may be able to use top_k instead, but that's would be inconsistent and unfamiliar for those who use vector search in postgres.

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@lmolkova I see your point but I think top-k has a different meaning from limit. If you are using a relation database as vector db, limit is fine since you are building an SQL statement and you specify the order. But, if you are using a native vector database (e.g. Qdrant), the top-k is more relevant since top implies the order, using a similarity metric.

I think we should add both:

  • db.query.limit
  • db.vector.query.top-k

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@lmolkova I found that the SELECT LIMIT is not part of the SQL standard. A statement compliant with SQL standard is FETCH FIRST. Moreover, I discovered that we already have db.operation.parameter,<key> in the semantic convention. This means, we can have db.operation.parameter.fetch-first. I don't think we need to add a limit or fetch-first in db.query. What do you think?

At the same time, I believe we should include db.vector.query.top-k. As noted earlier, it differs in meaning from fetch-first and, additionally, this parameter is much easier to retrieve in a vector database because it's not part of any statement.

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We need to reference new attributes in the database spans conventions (see https://github.com/open-telemetry/semantic-conventions/blob/main/model/trace/database.yaml), specifically on the conventions for the databases we have there which support vector search.

We should describe how new attributes apply to them.

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@lmolkova lmolkova added never stale PRs marked with this label will be never staled and automatically closed and removed Stale labels Oct 25, 2024
@lmolkova lmolkova reopened this Oct 25, 2024
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lmolkova commented Oct 25, 2024

@ezimuel I'm sorry I did not reply earlier. I'm swamped with some work at the moment and, unfortunately, it might take me some time to reply.

If you look into https://github.com/open-telemetry/semantic-conventions/tree/main/docs/database you'd see that we have some docs for individual database systems - we reference attributes from the registry and we explain how these attributes apply to this system (or don't apply).

This is powered by the yaml in https://github.com/open-telemetry/semantic-conventions/tree/main/model/database.

Please look at the existing database conventions and update them to include new attributes you're adding.

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ezimuel commented Nov 5, 2024

@lmolkova thanks for the information and sorry also on my side for the late reply, very busy period.
I'm looking into the examples that you shared and I'll send a commit soon.

@ezimuel ezimuel requested a review from a team as a code owner December 2, 2024 14:50
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ezimuel commented Dec 2, 2024

@lmolkova and @AlexanderWert I finally found some time to work on this PR. I’ve added the spans definition and updated the documentation. I hope everything looks good. Looking forward to your review. Thanks!

@@ -764,3 +764,81 @@ groups:
- ref: db.cosmosdb.regions_contacted
requirement_level:
conditionally_required: If available.

- id: span.db.vector.client
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postgres, cosmos, mongodb, elasticsearch and others are vector databases too and we need to update their conventions to say how to record vector search capabilities for them

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agree, but how about doing it in a follow up issue / PR, as it is additive information?

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I don't think we should introduce span.db.vector.client span - it's not clear what/when/how will report it.
Also, referencing attributes in the specific conventions is a good test if these attributes are applicable and properly named/described to fit to specific db implementations.

E.g. db.vector.query.top_k debate will become obvious on postgres - you can't have an attribute like this there and would have to call it db.query.limit or similar.

It's ok to limit the scope to several DBs and not cover all possible details.

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I don't think we should introduce span.db.vector.client span

Sorry, I don't get that. We also have a generic span.db.client (which then in addition has technology specific overrides). Wouldn't it be the same thing here, so having a generic description for vector db client spans + in addition having technology-specific overrides for the DBs listed above.

it's not clear what/when/how will report it

agree, in the readme above we need more explicit / clearer guidance on when to use span.db.vector.client vs. the more general span.db.client, but we should do it in a technology-independent way first.

Also, referencing attributes in the specific conventions is a good test if these attributes are applicable and properly named/described to fit to specific db implementations.
...
It's ok to limit the scope to several DBs and not cover all possible details.

Makes sense.

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I agree with @AlexanderWert . I think we should have a generic span.db.vector.client for vector databases that do not have technology-specific conventions, like the generic sql clients.
@lmolkova I see the issue with db.vector.query.top_k and db.query.limit, I think I can remove the top-k even if they are semantically different.

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Sorry, I don't get that. We also have a generic span.db.client (which then in addition has technology specific overrides). Wouldn't it be the same thing here, so having a generic description for vector db client spans + in addition having technology-specific overrides for the DBs listed above.

The problem is that none of the databases we have in the semconv should be considered a vector databases then. The span.db.vector.client is an abstract thing nothing is going to use. MongoDB, CosmosDB, elastic, postres - all of them are used as vector databases - will they extend span.db.vector.client? Will generic instrumentations for them cover vector-related operations?

Also we're trying to introduce attributes without attempting to apply them to existing databases - this is the major blocker I see in this PR.

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ezimuel and others added 5 commits December 5, 2024 09:26
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ezimuel commented Dec 5, 2024

Thanks @AlexanderWert for the feedback.


| Value | Description | Stability |
|---|---|---|
| `cosine` | The cosine metric. | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
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nit:

  1. There are cosine similarity and cosine distance. Better to distinguish the two in the convention.
  2. There are a few common ones that are not listed here: Squared Euclidean and hamming.


**[11] `db.elasticsearch.path_parts`:** Many Elasticsearch url paths allow dynamic values. These SHOULD be recorded in span attributes in the format `db.elasticsearch.path_parts.<key>`, where `<key>` is the url path part name. The implementation SHOULD reference the [elasticsearch schema](https://raw.githubusercontent.com/elastic/elasticsearch-specification/main/output/schema/schema.json) in order to map the path part values to their names.
`db.search.similarity_metric` has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.
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The similarity metric doesn't need to be defined per search request. It can also be defined when the collection is created.


| Attribute | Type | Description | Examples | Stability |
|---|---|---|---|---|
| <a id="db-vector-dimension-count" href="#db-vector-dimension-count">`db.vector.dimension_count`</a> | int | The dimension of the vector. | `3` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
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nit: db-vector-dimension-count -> db-vector-dimension.

| Attribute | Type | Description | Examples | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability |
|---|---|---|---|---|---|
| [`db.operation.name`](/docs/attributes-registry/db.md) | string | The operation to be performed on the vector database (e.g. build an index/collection) [1] | `build`; `insert`; `search`; `delete` | `Required` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
| [`http.request.method`](/docs/attributes-registry/http.md) | string | HTTP request method. [2] | `GET`; `POST`; `HEAD` | `Required` | ![Stable](https://img.shields.io/badge/-stable-lightgreen) |
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http.request.method should not be used on generic database span

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