[Feature][Integration][Java] Add Milvus vector store integration by yanbinyang · Pull Request #663 · apache/flink-agents

yanbinyang · 2026-05-12T12:28:14Z

Linked issue: #661

Purpose of change

This PR implements the Java version of Milvus-based Vector Store functionality for Flink Agents, following the design proposal in #143. This implementation enables RAG (Retrieval-Augmented Generation) capabilities by providing vector-based context retrieval.

Added Milvus vector store integration
Added Milvus vector store module under integrations/vector-stores
Supported Milvus connection and query configuration
Converted Milvus search results into the common Document format
Added tests for Milvus vector store behavior

Tests

API

Documentation

doc-needed
doc-not-needed
doc-included

wenjin272

Thanks for your contribution @yanbinyang. Overall looks good to me, and I left serveral minor comments.

I think we should also verify Milvus in the test case Mem0LongTermMemoryTest. This test is currently disabled due to a bug in Flink itself, which is expected to be fixed in the coming weeks. There are also workarounds available for local execution. You can add the test path for Milvus, and I will verify it locally.

wenjin272 · 2026-05-13T10:56:37Z


 ### Concepts
 * **Document**: Document is the abstraction that represents a piece of text and associated metadata. A document may also carry a pre-computed `embedding` vector and a `score` populated by query results.
+* **Collection**: Collection is the abstraction that represents a set of documents. It corresponds to different concept for different vector store specification, like index in Elasticsearch/OpenSearch and collection in Chroma/Milvus.


It looks like there were some conflicts during the rebase. In a previous PR, we removed the Collection data structure and this line of description.

It looks like there were some conflicts during the rebase. In a previous PR, we removed the Collection data structure and this line of description.

Thanks for catching this. Removed the stale Collection concept line in ae1261a

wenjin272 · 2026-05-13T11:06:00Z

+    }
+
+    /** Returns the lazily-created Milvus client. */
+    private MilvusClientV2 client() {


Since flink-agents supports asynchronous execution of actions, meaning that multiple threads can invoke the same vector store simultaneously, connection leaks caused by multi-threading may occur here.

I suggest adding DCL.

Since flink-agents supports asynchronous execution of actions, meaning that multiple threads can invoke the same vector store simultaneously, connection leaks caused by multi-threading may occur here.

I suggest adding DCL.

Good point. Addressed in 56cc845 by making the Milvus client volatile and using double-checked locking for lazy initialization. I also synchronized close() so concurrent action execution will not create or leak multiple clients.

wenjin272 · 2026-05-13T11:17:27Z

It appears that this file is not being used in the CI. I'm wondering if we could also align the current Elasticsearch startup process in the CI with that of Milvus.

It appears that this file is not being used in the CI. I'm wondering if we could also align the current Elasticsearch startup process in the CI with that of Milvus.

Addressed in 37c5436. The cross-language CI job now starts and stops Elasticsearch via tools/docker/elasticsearch/docker-compose.yml, aligned with the Milvus startup flow.

yanbinyang · 2026-05-14T05:05:36Z

Thanks for your contribution @yanbinyang. Overall looks good to me, and I left serveral minor comments.

I think we should also verify Milvus in the test case Mem0LongTermMemoryTest. This test is currently disabled due to a bug in Flink itself, which is expected to be fixed in the coming weeks. There are also workarounds available for local execution. You can add the test path for Milvus, and I will verify it locally.

Thanks for the suggestion. Addressed in fa34054 by adding a Milvus path to Mem0LongTermMemoryTest: the test now parameterizes the Mem0 vector store over Elasticsearch and Milvus, and Mem0LongTermMemoryAgent declares a milvusLtmStore resource.

I couldn't run this e2e test locally because it still depends on the existing Pemja/Flink issue workaround and a local Milvus/Mem0 environment. Could you please help verify the Milvus path locally?

wenjin272

The code looks good to me, and I have verified using mem0 with mivlus locally, it works well.

However, there are still some issues with the commit organization in this PR. We require each PR branch to be rebased onto main rather than merged, in order to maintain a linear history on the main branch.

Signed-off-by: YangYanbin <warlock.yyb@alibaba-inc.com>

yanbinyang · 2026-05-18T03:12:50Z

Thanks. I have rebased the branch onto the latest main and force-pushed the updated linear history. The merge commit has been removed, and the PR is now mergeable.

wenjin272

LGTM

Resolve conflict in vector_store_cross_language_test.py: main (apache#663, Milvus integration) refactored the test into _run_vector_store_integration helper with two backend-specific test functions (ELASTICSEARCH, MILVUS). Reapply our Round 2 env-var fix on top of that structure: keep the module-scope os.environ["OLLAMA_EMBEDDING_MODEL"] = OLLAMA_MODEL removal, and add monkeypatch.setenv("OLLAMA_EMBEDDING_MODEL", OLLAMA_MODEL) inside the helper so both backends get the env var hygiene.

github-actions Bot added doc-needed Your PR changes impact docs. fixVersion/0.3.0 The feature or bug should be implemented/fixed in the 0.3.0 version. priority/major Default priority of the PR or issue. labels May 12, 2026

yanbinyang force-pushed the dev/milvus-vector-store branch 2 times, most recently from 29978ea to 2237ed7 Compare May 12, 2026 13:15

wenjin272 self-requested a review May 13, 2026 08:24

wenjin272 reviewed May 13, 2026

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wenjin272 reviewed May 15, 2026

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wenjin272 added doc-included Your PR already contains the necessary documentation updates. and removed doc-needed Your PR changes impact docs. labels May 15, 2026

yanbinyang added 5 commits May 18, 2026 10:54

[Feature][Integration][Java] Add Milvus vector store integration

9352e3b

Signed-off-by: YangYanbin <warlock.yyb@alibaba-inc.com>

[docs] Remove stale vector store collection concept

e424534

[integration] Guard Milvus client lazy initialization

8068cc5

[test][java] Support Milvus in Mem0 long-term memory e2e

ad4fce1

Signed-off-by: YangYanbin <warlock.yyb@alibaba-inc.com>

[ci] Start Elasticsearch with docker compose

3046535

Signed-off-by: YangYanbin <warlock.yyb@alibaba-inc.com>

yanbinyang force-pushed the dev/milvus-vector-store branch from 7d77694 to 3046535 Compare May 18, 2026 02:57

wenjin272 approved these changes May 18, 2026

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wenjin272 merged commit 2d2b562 into apache:main May 18, 2026
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weiqingy mentioned this pull request May 19, 2026

[hotfix] Make Ollama embedding test actually run in CI #686

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[Feature][Integration][Java] Add Milvus vector store integration - #663

[Feature][Integration][Java] Add Milvus vector store integration#663
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yanbinyang commented May 12, 2026 •

edited by wenjin272

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