Blob Store API | Apache Solr Reference Guide 6.6

The Blob Store REST API provides REST methods to store, retrieve or list files in a Lucene index.

It can be used to upload a jar file which contains standard solr components such as RequestHandlers, SearchComponents, or other custom code you have written for Solr. Schema components do not yet support the Blob Store.

When using the blob store, note that the API does not delete or overwrite a previous object if a new one is uploaded with the same name. It always adds a new version of the blob to the index. Deletes can be performed with standard REST delete commands.

The blob store is only available when running in SolrCloud mode. Solr in standalone mode does not support use of a blob store.

The blob store API is implemented as a requestHandler. A special collection named ".system" is used to store the blobs. This collection can be created in advance, but if it does not exist it will be created automatically.

About the .system Collection

Before uploading blobs to the blob store, a special collection must be created and it must be named .system. Solr will automatically create this collection if it does not already exist, but you can also create it manually if you choose.

The BlobHandler is automatically registered in the .system collection. The solrconfig.xml, Schema, and other configuration files for the collection are automatically provided by the system and don’t need to be defined specifically.

If you do not use the -shards or -replicationFactor options, then defaults of numShards=1 and replicationFactor=3 (or maximum nodes in the cluster) will be used.

You can create the .system collection with the Collections API, as in this example:

curl http://localhost:8983/solr/admin/collections?action=CREATE&name=.system&replicationFactor=2

The bin/solr script cannot be used to create the .system collection.

Upload Files to Blob Store

After the .system collection has been created, files can be uploaded to the blob store with a request similar to the following:

curl -X POST -H 'Content-Type: application/octet-stream' --data-binary @{filename} http://localhost:8983/solr/.system/blob/{blobname}

For example, to upload a file named "test1.jar" as a blob named "test", you would make a POST request like:

curl -X POST -H 'Content-Type: application/octet-stream' --data-binary @test1.jar http://localhost:8983/solr/.system/blob/test

A GET request will return the list of blobs and other details:

curl http://localhost:8983/solr/.system/blob?omitHeader=true

Output:

{
  "response":{"numFound":1,"start":0,"docs":[
      {
        "id":"test/1",
        "md5":"20ff915fa3f5a5d66216081ae705c41b",
        "blobName":"test",
        "version":1,
        "timestamp":"2015-02-04T16:45:48.374Z",
        "size":13108}]
  }
}

Details on individual blobs can be accessed with a request similar to:

curl http://localhost:8983/solr/.system/blob/{blobname}

For example, this request will return only the blob named 'test':

curl http://localhost:8983/solr/.system/blob/test?omitHeader=true

Output:

{
  "response":{"numFound":1,"start":0,"docs":[
      {
        "id":"test/1",
        "md5":"20ff915fa3f5a5d66216081ae705c41b",
        "blobName":"test",
        "version":1,
        "timestamp":"2015-02-04T16:45:48.374Z",
        "size":13108}]
  }
}

The filestream response writer can return a particular version of a blob for download, as in:

curl http://localhost:8983/solr/.system/blob/{blobname}/{version}?wt=filestream > {outputfilename}

For the latest version of a blob, the {version} can be omitted,

curl http://localhost:8983/solr/.system/blob/{blobname}?wt=filestream > {outputfilename}

Use a Blob in a Handler or Component

To use the blob as the class for a request handler or search component, you create a request handler in solrconfig.xml as usual. You will need to define the following parameters:

class: the fully qualified class name. For example, if you created a new request handler class called CRUDHandler, you would enter org.apache.solr.core.CRUDHandler.
runtimeLib: Set to true to require that this component should be loaded from the classloader that loads the runtime jars.

For example, to use a blob named test, you would configure solrconfig.xml like this:

<requestHandler name="/myhandler" class="org.apache.solr.core.myHandler" runtimeLib="true" version="1">
</requestHandler>

If there are parameters available in the custom handler, you can define them in the same way as any other request handler definition.

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