Enable Semantic Search CCS When ccs_minimize_roundtrips=true #135309

Mikep86 · 2025-09-23T20:48:15Z

Enables CCS when ccs_minimize_roundtrips=true for the semantic query and for intercepted match, knn, and sparse_vector queries that target semantic_text fields.

Best effort detection for unsupported ccs_minimize_roundtrips=false cases has been implemented as well. However, one case in particular is impossible to detect right now:

Intercepted query usage (i.e. match, knn, or sparse_vector)
The only semantic_text field targeted is on a remote cluster

In this case, the query is not intercepted on the local cluster and the original query is sent to the remote cluster data nodes, resulting in an error about the intercepted query not supporting semantic_text fields. Tests have been added to validate this behavior.

…ests

dimitris-athanasiou

A few comments from a first pass before looking into the integration test.

.../inference/src/main/java/org/elasticsearch/xpack/inference/queries/SemanticQueryBuilder.java

...in/java/org/elasticsearch/xpack/inference/queries/InterceptedInferenceMatchQueryBuilder.java

.../elasticsearch/xpack/inference/queries/AbstractInterceptedInferenceQueryBuilderTestCase.java

kderusso

I did a first pass on this and my feedback is very minor, often nitpicky 😄

Overall it looks really good - nice changes that build on top of the previous PRs and thorough testing.

As we discussed, there will be additional followup work to test this "in practice" once it's in snapshot.

I don't have blocking feedback so I'll approve.

...rence/src/test/java/org/elasticsearch/xpack/inference/queries/SemanticQueryBuilderTests.java

...rc/main/java/org/elasticsearch/xpack/inference/queries/InterceptedInferenceQueryBuilder.java

...ava/org/elasticsearch/xpack/inference/queries/InterceptedInferenceKnnVectorQueryBuilder.java

kderusso · 2025-09-24T18:12:47Z

...rc/main/java/org/elasticsearch/xpack/inference/queries/InterceptedInferenceQueryBuilder.java


-        // TODO: Check for supported CCS mode here (once we support CCS)
-        if (resolvedIndices.getRemoteClusterIndices().isEmpty() == false) {
+        boolean ccsRequest = this.ccsRequest || resolvedIndices.getRemoteClusterIndices().isEmpty() == false;


Is ccsRequest set to false but at least one remote index specified a valid state to be in? I feel like this should be a 400 error that happens early during validation?

Yes, because ccsRequest is set to false upon initial query construction in most code paths. The important thing is that once ccsRequest is true, it remains set to that, hence the logical OR here. Transitioning from false to true (when resolvedIndices.getRemoteClusterIndices().isEmpty() == false) during rewrite is fine.

kderusso · 2025-09-24T18:14:38Z

...rc/main/java/org/elasticsearch/xpack/inference/queries/InterceptedInferenceQueryBuilder.java

                    + " query does not support cross-cluster search when querying a ["
                    + SemanticTextFieldMapper.CONTENT_TYPE
-                    + "] field"
+                    + "] field when [ccs_minimize_roundtrips] is false"


I wonder if it would be friendlier to change the wording of this, to something more along the lines of Set ccs_minimize_roundtrips to true to query semantic_text fields

That could be misleading in its own right. There are code paths that trigger CCS that don't allow setting ccs_minimize_roundtrips. The big one is ES|QL, which always performs CCS as if ccs_minimize_roundtrips=false. Returning an error with a suggestion that doesn't apply to all scenarios would probably cause more confusion.

Of course, that also means that the current error message could be confusing in such scenarios as well. I just couldn't think of a better way to state the problem both generically (to cover ES|QL) and specifically (when the user can change ccs_minimize_roundtrips). Thoughts?

.../inference/src/main/java/org/elasticsearch/xpack/inference/queries/SemanticQueryBuilder.java

.../elasticsearch/xpack/inference/queries/AbstractInterceptedInferenceQueryBuilderTestCase.java

kderusso · 2025-09-24T18:29:26Z

.../src/internalClusterTest/java/org/elasticsearch/search/ccs/SemanticCrossClusterSearchIT.java

Either breaking this up, and/or (better yet) consolidating some of the code as there's a lot of boilerplate here would be helpful. Really at the end of the day, a semantic, match and sparse vector search against a sparse embedding model should return the same results, ditto for semantic, match and knn over a text embedding model.

kderusso · 2025-09-24T18:29:51Z

...ti-cluster-search/src/test/resources/rest-api-spec/test/multi_cluster/110_semantic_query.yml

Friendly reminder to update rest compatibility so this test isn't executed.

… type

ioanatia · 2025-09-25T10:46:59Z

...lusterTest/java/org/elasticsearch/search/ccs/AbstractSemanticCrossClusterSearchTestCase.java

+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.is;
+
+public abstract class AbstractSemanticCrossClusterSearchTestCase extends AbstractMultiClustersTestCase {


I was just about to ask about yaml tests - but since we have these I don't think we need other integration tests?

I don't think so. These integration tests cover every case I think we need for CCS right now.

ioanatia · 2025-09-25T10:48:12Z

server/src/main/resources/transport/upper_bounds/8.18.csv

@@ -1 +1 @@
-initial_elasticsearch_8_18_8,8840010
+transform_check_for_dangling_tasks,8840011


weird that CI pushed this changes - probably merging main here will make these disappear

Still figuring out the new "simplified" transport versions. There are some rough edges :)

ioanatia · 2025-09-25T10:50:36Z

x-pack/plugin/inference/src/main/plugin-metadata/entitlement-policy.yaml

 io.netty.common:
  - outbound_network
  - manage_threads
+  - inbound_network


we don't see these files changed often - just for me to understand - why is this needed?

We need these permissions so that the two clusters in the CCS integration tests can communicate. We didn't have CCS integration tests in the inference plugin before this, hence the change.

dimitris-athanasiou

LGTM I think it's fine to merge this and clean up tests as a follow up.

… inference results map

Mikep86 added 25 commits September 19, 2025 08:37

Added transport version

8a7069f

Added skeleton for semantic cross-cluster search integration tests

f2e8d10

Updated semantic query to support CCS

d444199

Added semantic query CCS integration test

3133d6f

Added semantic query CCS serialization test

679f3c0

Deleted obsolete YAML test

d02419c

Updated legacy semantic query rewrite interceptors to detect CCS requ…

f9d0d51

…ests

Added semantic query CCS test when ccs_minimize_roundtrips=false

fc7fadc

Fix random test failure

c439bd2

Adjust error message format

7db5ff8

Updated InterceptedInferenceQueryBuilder to add CCS support

455055a

Added match query CCS test

990f69a

Fix build error

3fc3e5b

Added knn query CCS test

2ce408a

Use fully qualified inference ID to disambiguate inference ID overrides

ec40327

CCS test refactoring

fe71bc7

Extended match query CCS test

e7269e6

Added sparse vector query CCS test

deeefcb

Added test cases using query vectors

1d38967

Added match query test with ccs_minimize_roundtrips=false

3c1acdf

Added knn query test with ccs_minimize_roundtrips=false

9fd9c66

Added sparse vector query test with ccs_minimize_roundtrips=false

e929355

Added CCS serialization test for intercepted queries

3815f26

Fixed test failures

c82d083

Fixed test failures

588eebd

Mikep86 requested review from dimitris-athanasiou, ioanatia and kderusso September 23, 2025 20:48

Mikep86 added >enhancement :SearchOrg/Relevance Label for the Search (solution/org) Relevance team labels Sep 23, 2025

dimitris-athanasiou reviewed Sep 24, 2025

View reviewed changes

kderusso approved these changes Sep 24, 2025

View reviewed changes

Mikep86 and others added 2 commits September 24, 2025 17:13

Refactored CCS integration tests into separate classes for each query…

9000d35

… type

[CI] Update transport version definitions

88fafad

ioanatia reviewed Sep 25, 2025

View reviewed changes

Mikep86 added 4 commits September 25, 2025 09:33

Merge branch 'main' into semantic-search_enable-ccs

7f071f0

Fix transport version

60f9be4

Remove IVF_FORMAT feature flag references

fdf1ccf

Knn CCS test refactoring

b4721fd

dimitris-athanasiou approved these changes Sep 25, 2025

View reviewed changes

Mikep86 added 14 commits September 25, 2025 10:42

Adjusted and documented ccsRequest usage in SemanticQueryBuilder

00fe101

Fix typo

cf70b70

Refactored intercepted query CCS serialization tests

9d5c68a

Refactored semantic query CCS serialization tests

bab63a5

Updated intercepted queries to add a constructor for setting only the…

d9be362

… inference results map

Simplify intercepted knn query getInferenceIdOverride implementation

441eba4

Updated error message

4074052

Added convenience constructor for semantic query

2e49792

Adjusted error message

e0a7187

Merge branch 'main' into semantic-search_enable-ccs

d4d8f24

Update transport version

da5ebb6

Match query CCS test refactoring

b6e6e6c

Integrated index boosts into CCS integration tests

c124e02

Updated match query CCS tests to use a common cluster configuration

825bc9a

ioanatia approved these changes Sep 25, 2025

View reviewed changes

Mikep86 added 4 commits September 25, 2025 15:09

Semantic query CCS test refactoring

3beb2d8

Sparse vector query CCS test refactoring

7333107

Merge branch 'main' into semantic-search_enable-ccs

e082519

Update transport version

0794501

Mikep86 merged commit 7613137 into elastic:main Sep 25, 2025
34 checks passed

		@@ -1 +1 @@
		initial_elasticsearch_8_18_8,8840010
		transform_check_for_dangling_tasks,8840011

Enable Semantic Search CCS When ccs_minimize_roundtrips=true #135309

Enable Semantic Search CCS When ccs_minimize_roundtrips=true #135309

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Mikep86 commented Sep 23, 2025

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