Elasticsearch Alternatives

2022-01: We are adding support for https://dev.tiki.org/Manticore-Search

Unfortunately, Elasticsearch is no longer Open Source: https://www.elastic.co/blog/licensing-change
https://www.elastic.co/blog/license-change-clarification

Meanwhile, organizations that refuse to run proprietary software in production will no longer be able to run Elasticsearch in good conscious (at least, not the SSPL versions). I work for Wikimedia and we use Elasticsearch to power article search. We're going to have to drop it.
— Ryan Kemper (@RyanKemper10) January 15, 2021

https://opensource.org/node/1099

Context

Context: https://doc.tiki.org/Unified-Index-Comparison

Also, So, i think for Virtualmin 7 (...) we’ll switch the default database in Virtualmin installations to mariadb for all distros.

Goals

For the default Tiki Unified Index engine to be suitable for most projects, as has been for many years with MySQL/MariaDB using the MyISAM storage engine.
- Ideally, can be used for https://doc.tiki.org/Federated-Search for *.tiki.org
- Ideally, performance is good enough that it can be used for search on avan.tech, and proposals.evoludata.com
- Ideally, we can add facets
- Ideally, we address MySQL-limitations-for-Unified-Index
For advanced needs, support an Open Source solution (candidates are listed below) to replace our use of Elasticsearch of the last few years.
Switching between options should produce same results in lists (Although full text search results will vary because relevance algorithm will be different)
Revisit our discussion about the abstraction layer
Make it clear how functionality may change with non-default engine
Integrate with Rubix ML as was done for More Like This
Maintain Elasticsearch support on current versions (Until end of life of Tiki 21.x LTS) but not in Tiki 24.x unless it's very little work.
https://wikisuite.org/Component-criteria
Segmentation: Each Virtualmin Virtual Server should have its own data.
- Open Distro offers role-based access control/multi-tenancy