Enable schema API support for Solr by switching to ManagedIndexSchemaFactory

Goal

Programmatically add or delete fields in a Solr collection schema using the Schema API without manually editing schema.xml.

Environment

Solr 8.11 and above.
This guide assumes Solr is deployed in SolrCloud mode and managed via ZooKeeper.

Guide

Update Solr to use ManagedIndexSchemaFactory

To enable Schema API operations, Solr must use ManagedIndexSchemaFactory. If the current solrconfig.xml uses ClassicIndexSchemaFactory, the schema will be read-only and any attempt to use the Schema API will return schema is not editable.

Steps:

1. Open the solrconfig.xml file for each configset used by your collections.

2. Locate the following line:

   <schemaFactory class="ClassicIndexSchemaFactory"/>

3. Replace it with:

   <schemaFactory class="ManagedIndexSchemaFactory"/>

4. Upload the updated configset to ZooKeeper:

   $SOLR_HOME/server/scripts/cloud-scripts/zkcli.sh -zkhost <ZK_HOST> -cmd upconfig -confdir <configset_dir> -confname <configset_name>

5. Reload the associated collection:

   curl http://<solr_host>:8983/solr/admin/collections?action=RELOAD&name=<collection_name>

Note: Replace <ZK_HOST>, <configset_dir>, <configset_name>, <solr_host>, and <collection_name> with your actual values.

Once reloaded, the UI should reflect a new managed-schema file alongside a .bak version of the old schema.xml.

Add or remove fields using the Schema API

You can now use curl, Postman, or other REST clients to add or remove fields.

Example API call to add a field:

curl -u <username>:<password> -X POST -H 'Content-type:application/json' --data-binary '{
"add-field": {
"name":"recurring_amt",
"type":"string",
"stored":true
}
}' http://<solr_host>:8983/api/collections/<collection_name>/schema

Note: Ensure the target collection is using a configset that has been updated and reloaded with ManagedIndexSchemaFactory.

Reindexing considerations

Not all schema changes require reindexing. Typically:

• Adding new fields that are not used in existing queries: no reindexing required

• Modifying properties like stored or indexed: no reindexing required

• Changing field types or analyzers: reindexing required

Refer to the Solr documentation for more guidance: https://solr.apache.org/guide/8_11/reindexing.html

Troubleshooting tip

If after updating solrconfig.xml and reloading the collection the Schema API still returns "schema is not editable", verify:

• The config was successfully pushed to ZooKeeper using zkcli.sh

• The collection was reloaded post-upload

• The managed-schema file is visible in the Admin UI

Restarting Solr is not required after using the Schema API if all the above steps are completed correctly.