Using external catalogs


The Plone catalog can be extend to use external catalogs like Solr or Elasticsearch. Add-ons like collective.solr use that to hook into the catalog API and do some Indexing outside of Plone in Solr, which increases performance and flexibility of indexing a lot.

Implement IIndexingQueueProcessor

To hook into the catalog one can implement the IIndexingQueueProcessor interface from Products.CMFCore.

New in version 5.1: For Plone versions before 5.1 you need to use the interfaces from collective.indexing package!

class IIndexQueueProcessor(IIndexing):
    """A queue processor, i.e. an actual implementation of index operations
    for a particular search engine, e.g. the catalog, solr etc

    def begin():
        """Called before processing of the queue is started"""

    def commit():
        """Called after processing of the queue has ended"""

    def abort():
        """Called if processing of the queue needs to be aborted"""

Implement IIndexing

And also the underlying IIndexing interface.

class IIndexing(Interface):
    """ interface for indexing operations, used both for the queue and
        the processors, which perform the actual indexing;  the queue gets
        registered as a utility while the processors (portal catalog, solr)
        are registered as named utilties """

    def index(obj, attributes=None):
        """ queue an index operation for the given object and attributes """

    def reindex(obj, attributes=None):
        """ queue a reindex operation for the given object and attributes """

    def unindex(obj):
        """ queue an unindex operation for the given object """

Example implementation

For an example implementation of an external IndexingQueueProcessor, look at the SolrIndexProcessor of collective.solr, which implements ISolrIndexQueueProcessor (IIndexQueueProcessor).

Catalog queue and tests

When running tests, specially during the transition to Plone 5.1, some tests might fail due to the queue holding back and processing until a transaction happens.

If that behavior is not desired one can use the CATALOG_OPTIMIZATION_DISABLED environment variable to disable the catalog queue.