adityamparikh opened a new issue, #183:
URL: https://github.com/apache/solr-mcp/issues/183
## Summary
`create-collection` binds each new collection directly to the shared
`_default` configset instead
of giving it its own copy. Because `_default` has data-driven (schemaless)
mode enabled, the first
collection's **guessed field types are written into the shared
managed-schema in ZooKeeper**, and
every collection created afterwards inherits them.
Since Solr field types cannot be modified once created, the second
collection is permanently stuck
with the first one's guesses.
## Reproduction
Solr 9, SolrCloud, empty cluster.
```
1. create-collection name=shows-auto
2. index-json-documents collection=shows-auto (schemaless guessing
runs)
3. create-collection name=shows
4. add-fields collection=shows (explicit types)
```
Step 4 fails:
```
error processing commands, errors: [{add-field={name=title,
type=text_general, ...},
errorMessages=[Field 'title' already exists.]}, {add-field={name=platform,
type=string, ...},
errorMessages=[Field 'platform' already exists.]}, ...]
```
`get-schema` on the brand-new, never-indexed `shows` collection returns step
2's guesses:
```json
{"name": "platform", "type": "text_general"}
{"name": "imdb_rating", "type": "pdoubles"}
{"name": "release_year", "type": "plongs"}
```
`CLUSTERSTATUS` confirms the sharing:
```
shows -> configName: _default
shows-auto -> configName: _default
```
The leak runs in both directions — create a collection with an explicit
schema first, and a later
collection silently inherits *those* types instead, so it is not schemaless
at all.
## Root cause
[`CollectionService.java:1146`](https://github.com/apache/solr-mcp/blob/main/src/main/java/org/apache/solr/mcp/server/collection/CollectionService.java#L1146):
```java
CollectionAdminRequest.createCollection(name, effectiveConfigSet,
effectiveShards, effectiveRf)
.process(solrClient);
```
with `effectiveConfigSet` defaulting to `_default`. This attaches the
collection to that configset
by reference.
For contrast, `bin/solr create -c foo -n _default` **copies** `_default`
into a new configset named
after the collection, which is why the same sequence works from the CLI.
## Suggested fix
Have `create-collection` upload a per-collection copy of the source
configset (e.g. via
`ConfigSetAdminRequest.Create` with `baseConfigSetName`) and point the new
collection at the copy,
matching `bin/solr create` behaviour. The explicit `configSet` parameter
should keep its current
meaning of naming the *base* to copy from.
## Impact
Two distinct failures, neither of which points at the real cause:
1. **`add-fields` fails with `Field 'x' already exists`** on a collection
that was just created and
never indexed. The message gives no hint that another collection is
responsible.
2. **Schema silently leaks across collections.** A collection can end up
with field types nobody
defined for it, and because types are immutable, there is no recovery
short of recreating the
configset or the cluster.
The natural MCP workflow — *"create a collection, then set up its schema"*,
which the built-in
`setup-collection` and `design-schema` prompts both encourage — hits this
whenever more than one
collection exists.
## Workaround
Restart Solr (or otherwise reset `_default`) between collections. For a
single container:
```bash
docker rm -f <container> && docker run -d --name <container> -p 8983:8983
solr:9-slim solr start -c -f
```
## Environment
- `main` @ `a84033b`; `CollectionService.java` unmodified at that commit
- Solr 9 (`solr:9-slim`), SolrCloud mode with embedded ZooKeeper
- solr-mcp 1.0.0-SNAPSHOT, Spring Boot 3.5.14
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