One of the things we often notice about existing systems based on relational databases (RDB) is that as they scale to millions of items, simple lookup tasks become slow and inefficient. These tasks don’t usually require complicated database operations, so in most cases it is possible to relocate the data from the RDB into a search engine like Flax.
Consider a system where a search engine has already been implemented to search textual product information, but numerical data on each product, such as price, is still being stored in a RDB. Users will often need filters on search results such as ‘show me items under £10’ and so a RDB operation similar to ‘
SELECT productID FROM products WHERE price<£10‘ will be needed, in addition to the search engine query. Modern search engines like Flax implement range search functions, so that numerical information can be added to documents, and it is thus possible to carry out this operation in the search engine as part of the full-text search for the product information.
We’ve noticed with several clients that it is now possible to move all their data from the original RDB into the search engine. This can obviously lead to cost savings, as only one system must be hosted, maintained and backed up, and scaling out can be far simpler.
Another way to look at this is to consider a search engine as an example of a document-oriented database.