【Purview】DiscoveryClient query performance issue

Question

【Purview】DiscoveryClient query performance issue

Mofei Zhuang 120 Microsoft Employee

Hi Team，

 I’d like to ask about a query issue with `GetDiscoveryClient()`. Based on my understanding, `GetDiscoveryClient()` should return indexed data directly and shouldn’t trigger a secondary query, so I expected it to be quite fast. However, one of my queries, which only retrieves a single entity each time, takes around 3 seconds. I feel this performance is a bit slow.

Here is the condition for my Purview account, I think it doesn't reach the maximum limit of an account： Screenshot 2026-02-05 085429

What I searched is a Custom Define Entity, only have few attributes, here is the structure :

[

{

"Name": "ServiceId",

"TypeName": "string",

"IsOptional": true,

"Cardinality": "SINGLE",

"ValuesMinCount": 0,

"ValuesMaxCount": 1,

"IsUnique": true,

"IsIndexable": true

},

{

"Name": "ServiceName",

"TypeName": "string",

"IsOptional": true,

"Cardinality": "SINGLE",

"ValuesMinCount": 0,

"ValuesMaxCount": 1,

"IsUnique": true,

"IsIndexable": true

},

]

And here is the query I'm using :

var filters = new List<object>

{

new { typeName = "Service_Custom_Entity" },

new { attributeName = "ServiceId", @operator = "eq",  attributeValue = "XXXXXX"

};

var config = new QueryConfig

{

Limit = 1000,

Filter = BinaryData.FromObjectAsJson(new

{

    and = filters

}),

};

DataMapClient.GetDiscoveryClient().QueryAsync(config);

What I’d like to understand is whether a response time of around 3 seconds for this kind of single-entity query is within Purview’s SLA.

Manoj Kumar Boyini 5,795 Reputation points Microsoft External Staff Moderator

2026-02-04T23:34:19.77+00:00

Hi Mofei Zhuang,

A response time of around 2–3 seconds for DataMapClient.GetDiscoveryClient().QueryAsync() is not unexpected in Microsoft Purview Data Map, even when querying a single entity with indexed attributes.

QueryAsync() maps to Purview’s Discovery (search) API, which is designed for flexible search scenarios rather than direct key-value lookups. Even when attributes are marked as IsIndexable, the request still goes through a remote search pipeline, including authentication, authorization, filter evaluation, and result shaping. In many cases, the service or SDK then performs additional work to retrieve full entity details, which contributes to the observed latency.

Data Map capacity units (CUs) describe throughput and storage capacity, not per-request latency. Microsoft’s published SLAs focus on service availability, not guaranteed response times for individual search queries. Therefore, a ~3-second response for a discovery search does not indicate a service issue or SLA breach.

For your specific scenario retrieving exactly one entity by a unique attribute the recommended and more efficient approach is to use the Entity Get By Unique Attributes API. This endpoint is purpose-built for direct lookups using attributes marked as unique (such as your ServiceId) and returns the full entity in a single call, avoiding the general search path and reducing latency.

If you continue using QueryAsync, consider reducing Limit to a small value (for example, 1) and enabling client-side SDK logging to verify whether additional calls are occurring. However, for exact lookups, switching to the unique-attribute entity API is the best practice.
QueryAsync() is a search operation, not a direct index read.
~3 seconds can be normal for discovery queries.
For single-entity lookups by a unique attribute, use Get By Unique Attributes for better performance and predictable behavior.

Helpful references:
https://learn.microsoft.com/en-us/rest/api/purview/datamapdataplane/discovery/query?view=rest-purview-datamapdataplane-2023-09-01&tabs=HTTP
https://learn.microsoft.com/en-us/rest/api/purview/datamapdataplane/entity/get-by-unique-attributes?view=rest-purview-datamapdataplane-2023-09-01&tabs=HTTP
https://learn.microsoft.com/en-us/purview/data-gov-api-custom-types
https://learn.microsoft.com/en-us/purview/data-map

Hope this helps, Please let us know if you have any questions and concerns.
Mofei Zhuang 120 Reputation points Microsoft Employee

2026-02-05T01:13:38.9733333+00:00

I tried using DataMapClient.GetEntityClient().GetByUniqueAttributeAsync(), but the SDK has a limitation: no matter which attribute I pass to this method, it only recognizes the qualifiedName attribute.

here is the source code you can see it, the qualifiedName is a fixed value. I can use this method to search by serviceId.

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Mofei Zhuang 120 Reputation points Microsoft Employee

2026-02-05T01:13:38.9733333+00:00

I tried using DataMapClient.GetEntityClient().GetByUniqueAttributeAsync(), but the SDK has a limitation: no matter which attribute I pass to this method, it only recognizes the qualifiedName attribute.

here is the source code you can see it, the qualifiedName is a fixed value. I can use this method to search by serviceId.

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【Purview】DiscoveryClient query performance issue

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