Derive the Elasticsearch index name of a store in one place (#4929)

[batrived]

Fixes #4929.

Every read and write path maps a JanusGraph store name to an Elasticsearch index name through generateIndexStoreName, which lowercases the store. RestElasticSearchClient.clearStore composed the same name by hand and did not lowercase it.

A mixed index stores its JanusGraph index name as the store name verbatim, and JanusGraph index names are case-sensitive. So for an index named vertexByName:

written and queried as	<indexName>_vertexbyname
clearStore targeted	<indexName>_vertexByName

An Elasticsearch index name is always lowercase, so the second cannot exist. Either the existence check returned false and the call silently did nothing, or Elasticsearch rejected the name and ManagementSystem reported the misleading "Index removal is not supported for this Backend". Either way the documents remained while the schema was marked DISCARDED, so JanusGraph believed the data was gone.

Approach

I took the second option from the issue — removing the duplicated derivation rather than correcting it. ElasticSearchIndex.clearStore now derives the name through getIndexStoreName, the same call every other path uses, and passes it down. So the mapping exists in exactly one place and cannot drift again.

This changes an interface signature: ElasticSearchClient.clearStore(String indexName, String storeName) becomes clearStore(String indexStoreName). RestElasticSearchClient is the only implementation and ElasticSearchIndex the only caller, both in this module, so nothing else in the tree is affected. IndexProvider.clearStore(String storeName) is a different interface and is untouched.

If you would rather not change the signature, the one-line alternative from the issue — lowercasing inside clearStore — also fixes the reported bug, and I am happy to switch to it. I preferred this version because the duplication is the root cause.

Testing

Docker was not available to me, so I could not run the container-backed ElasticsearchIndexTest locally and did not want to add an integration test I could not verify. RestClientClearStoreTest unit-tests the client contract with a mocked RestClient: the existence check and the delete both address the exact name given, no delete is issued when the index is absent, and the method does not lowercase what it receives — which is what makes passing the pre-derived name correct.

The lowercasing itself stays covered by the existing paths, since getIndexStoreName is now the only derivation and every read and write already depends on it.

Also worth a look, not fixed here

Two things I noticed next to this code, both from your issue and both left alone deliberately:

• Because generateIndexStoreName lowercases, two mixed indexes differing only in case (byName and byname) map to the same Elasticsearch index and silently share documents. ManagementSystem.checkIndexName only enforces uniqueness on the JanusGraph side. That is a validation change, not a rename, so it belongs in its own PR.
• RestElasticSearchClient.deleteIndex does nothing at all when the name is not an alias, which looks unintended but is a separate concern.

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[Copilot]

Pull request overview

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This PR fixes mixed-index DISCARD_INDEX cleanup by ensuring the Elasticsearch index-store name is derived in one place (via getIndexStoreName) and passed through to clearStore unchanged, avoiding case-related mismatches.

Changes:

• Refactors ElasticSearchClient.clearStore to accept a pre-derived indexStoreName (signature change) and updates the REST implementation accordingly.
• Updates ElasticSearchIndex.clearStore to derive the index-store name via getIndexStoreName and improve the thrown error context.
• Adds a unit test covering the REST client clearStore contract (verbatim name usage + no delete when absent).

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
janusgraph-es/src/test/java/org/janusgraph/diskstorage/es/rest/RestClientClearStoreTest.java	Adds unit tests asserting clearStore uses the provided index-store name verbatim and guards deletion by existence.
janusgraph-es/src/main/java/org/janusgraph/diskstorage/es/rest/RestElasticSearchClient.java	Updates clearStore to operate on a single indexStoreName argument and removes duplicated name composition.
janusgraph-es/src/main/java/org/janusgraph/diskstorage/es/ElasticSearchIndex.java	Derives the index-store name once via getIndexStoreName and passes it to the client; updates exception message accordingly.
janusgraph-es/src/main/java/org/janusgraph/diskstorage/es/ElasticSearchClient.java	Changes the interface signature for clearStore and documents the “pre-derived name” contract.

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[porunov]

Reviewed, rebased on current master (no conflicts) and force-pushed as a single commit. Three of Copilot's four comments are applied; I replied on the fourth explaining why I kept Mockito.reset.

The bug is real, and I have it on film

Docker was the gap in your own verification, so I closed it. I added testClearStoreOfAMixedCaseStoreName to ElasticsearchIndexTest, which registers a store called vertexByName against a real Elasticsearch 9.5.4, asserts janusgraph_vertexbyname exists, calls index.clearStore("vertexByName") and asserts it is gone.

I then put the old derivation back, in clearStore only, and ran it again:

lowercase-exists-before=true   mixedcase-exists-before=false
lowercase-exists-after=true
ElasticsearchIndexTest.testClearStoreOfAMixedCaseStoreName:357 expected: <false> but was: <true>

So it is the silent branch of the two you described: indexExists("janusgraph_vertexByName") returns 404, no DELETE is issued, nothing is logged, and the documents are still there afterwards. No exception, no "Index removal is not supported for this Backend" — just data that outlives the schema entry which said it was discarded.

That test matters beyond confirming the bug: RestClientClearStoreTest pins the client contract, but nothing pinned the derivation in ElasticSearchIndex.clearStore itself, which is where the defect actually lived. A future change that passes storeName through again would have left the unit test green.

On the approach

I agree with taking the second option from the issue rather than the one-line toLowerCase(). The duplication is the root cause, the signature change is contained — RestElasticSearchClient is the only implementation of ElasticSearchClient and ElasticSearchIndex the only caller, both in this module — and IndexProvider.clearStore(String storeName) is a different interface and stays as it is. I verified all three of those rather than taking them on trust.

I also confirmed the premise: ManagementSystem.createMixedIndex sets INDEXSTORE_NAME to the index name verbatim, and checkIndexName only rejects blank or duplicate names, so an uppercase character in a mixed index name is entirely legal on the JanusGraph side.

Verification

RestClientClearStoreTest 3/3, ElasticsearchIndexTest 267/267 and ElasticsearchConfigTest 12/12 against a real Elasticsearch 9.5.4 container. Checkstyle clean.

Follow-ups

Both of the things you set aside are worth their own issues, and I agree with leaving them here:

• Two mixed indexes differing only in case map to the same Elasticsearch index and silently share documents, because generateIndexStoreName lowercases while checkIndexName only enforces uniqueness case-sensitively. That one is a validation change with an upgrade story, so it needs its own discussion.
• RestElasticSearchClient.deleteIndex doing nothing when the name is not an alias does look unintended.

[Copilot]

Copilot review overview

🟡 Changes recommended

The public client interface change lacks a compatibility path for downstream implementations and compiled consumers.

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Review effort: Balanced
Findings: 1

Open (1)

• Removing public interface method breaks source and binary compatibility · New

Resolved since last review (4)

• Using Mockito.reset is generally discouraged because it clears both stubbing and interaction…
• The comment claims an Elasticsearch index could “genuinely differ in case”, but Elasticsearch index…
• Since this is a public interface method, prefer a Javadoc comment (/** ... */) over line comments…
• This test asserts only the HTTP method for the existence check. To better lock down the contract…