11. Document model
Lucene, Xapian:
List of terms
Solr, Sphinx:
Fields in a predefined fixed schema.
Flax, Xappy:
Fields, with associated modifiable schema.
ElasticSearch:
Fields, document types, free schema.
12. Updates
Lucene, Xapian + families:
Dynamic updates
Use batches for fastest updates
Sphinx:
No updates to existing indexes
(“Realtime indexing” in beta with SQL API)
14. Scaling / replication
● All engines allow searches across databases
● Allows sharding
● All engines allow replication
● Allows spreading load and high availability
● Had difficulty with Sphinx
● Elastic search does it completely transparently