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Search Manual / Version 2207

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3.5.4 Reindexing Content Feeder and CAE Feeder Indices from Scratch

The most simple approach for Content Feeder and CAE Feeder indices is to clear the existing index and restart the Feeder. The Feeder will then reindex everything from scratch. In most cases this is not what you want, because search will be unavailable (or only return partial results) until reindexing has completed. See Section 4.6.4, “Clear Search Engine index” and Section 5.3.2, “Resetting” for instructions how to clear an existing index for Content Feeder and CAE Feeder, respectively.

A better solution is to feed a new index from scratch but keep using the old one for search until the new index is up to date. Applications can use the new index when reindexing is complete. When everything is fine, the old index can be deleted afterwards. This approach does not only have the advantage of avoiding search downtime but makes it also possible to test changes before enabling the index for all search applications.

To prepare a new index, you need to set up an additional Feeder and configure it to feed the new index. The new Feeder instance will eventually replace the existing Feeder instance.

The following steps describe the procedure for a standalone Solr server with optional leader/follower replication. For a SolrCloud cluster, different steps have to be taken. See the Solr Reference Guide at for reindexing into another SolrCloud collection.

  1. Add a new Solr core for the new index. The Solr Admin UI supports adding Solr cores in general but currently still lacks support for named config sets (SOLR-6728), so you have to create the new core with a HTTP request. To this end, you just need to send a request to the following URL with correct parameters, for example by opening it in your browser.


    1. Replace <hostname> and <port> with host name and port of the Apache Solr leader.

    2. Replace <name> with the name of the new core. You can choose any name you like as long as no such core and no such directory below the configured coreRootDirectory exists yet. If you are using Elastic Social you should also avoid names that start with the configured elastic.solr.index-prefix followed by an underscore (for example, blueprint_) to avoid name collisions with automatically created Solr cores.

    3. Replace <configSet> with the name of the config set of the new core. This should be "content" for Content Feeder indices and "cae" for CAE Feeder indices. Alternatively you can set it to the name of a custom config set, if you are using differently named config sets in your project.

  2. Check that the new core was successfully created in the coreRootDirectory. There should be a new subdirectory with the name of the newly created core which contains a file. For example, if a core studio2 with config set content was created, then <coreRootDirectory>/studio2/ should contain something like:

    #Written by CorePropertiesLocator
    #Mon Feb 27 14:45:44 UTC 2017

    You can also open the Solr Admin UI at http://<hostname>:<port>/solr, which shows the newly created core on the Core Admin page:

    New Solr Core

    Figure 3.1. New Solr Core

  3. Set up a new Feeder instance and configure it to feed into the new Solr core. In the Content Feeder, the name of the new core must be configured with property solr.content.collection. In the CAE Feeder, the name of the new core must be configured with property solr.cae.collection.

    For example, to configure a newly set up Content Feeder to feed into the new core with name studio2, set in


    In case of a CAE Feeder, you must also configure it with a separate empty database schema.

  4. Start the new Feeder and wait until the new index is up-to-date, for example by checking the log files or searching for a recent change in the new index. Depending on the size of the content repository this may take some time.

  5. Stop the Feeders for both the old and new Solr core.

  6. To activate the new index, it's now time to swap the cores so that the new core replaces the existing one. You can swap cores with the [Swap] button on the Core Admin page of the Solr Admin UI. Afterwards, all search applications automatically use the new core, which is now available under the original core name.

    Swap Solr Cores

    Figure 3.2. Swap Solr Cores

    It's important to understand that this operation does not change the directory structure in <coreRootDirectory> but just the name property in the respective files. For the example of swapping cores studio and studio2, you now have a newly indexed Solr core named studio in directory <coreRootDirectory>/studio2. You can verify this by looking into its file:

    #Written by CorePropertiesLocator
    #Mon Feb 27 15:06:27 UTC 2017
  7. Reconfigure the new Feeder instance to use the new core under the original name. To this end, the value of property solr.content.collection for the Content Feeder or property solr.cae.collection for the CAE Feeder needs to be changed accordingly. Start the new Feeder instance.

    For example, to configure the Content Feeder to feed into the new core which is now available under name studio, set in

  8. If you're using Solr replication, the new index will be replicated automatically to the Solr followers after a commit was made on the Solr leader for the new core. The restart of the Feeder in the previous step caused a Solr commit so that replication should have started automatically. If not, a Solr commit can also be triggered with a request to the following URL, for example in your browser with http://localhost:40080/solr/studio/update?commit=true for the Solr core named studio on the Solr leader running on localhost and port 40080.

    Note that depending on the index size, replication of the new core may take some seconds up to a few minutes during which the old index is still used when searching from Solr followers. You can see the progress of replication on the Solr follower's Admin UI on page Replication after selecting the corresponding core.

  9. To clean things up, you can now unload the old Solr core from the Solr leader with the [Unload] button on the Core Admin page of the Solr Admin UI. In the example, this would be the core named studio2.

    Unload old Solr Core

    Figure 3.3. Unload old Solr Core

    If you like, you can now also delete the old Feeder installation and the directory of the old Solr core with its index. In this example that would be <coreRootDirectory>/studio



You can use HTTP requests to perform the [Swap] and [Unload] actions instead of using the Solr Admin UI as described above. For details, see the Solr Reference Guide at

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