Hi there. I've been digging deeper into Elasticsearch lately, and I'm wondering about the ramifications of multiple types in a single index.
For some background, I got into Elasticsearch because a number of Ruby on Rails projects I've worked on use it. It seems to be idiomatic for the various Ruby gems to split up each document type into its own index.
However, that limits the ability to do parent-child queries and so on.
What's the story behind indices and types? Should they stay split up unless one needs to reason about the relationships between documents? Should they all go in a single index just for fun? Does it matter tremendously one way or another?
My instinct tells me to keep them separated. I would suspect (without any data to back it up) that ES has an easier time of just about everything (searching, indexing, storage, partitioning) when document types are broken out into different indices.