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I am a little confused by what you mean by columnar storage and "in fact, it doesn’t use indexes at all". Does that mean every columns (lines) are auto-indexed
by hartator 4y ago
I am a little confused by what you mean by columnar storage and "in fact, it doesn’t use indexes at all".
Does that mean every columns (lines) are auto-indexed? Can you use that strategy for storing things like users?
- wuputah 4y agoThe metadata can act as a basic form of indexing (or sometimes caching, though Hydra doesn't use metadata to calculate results yet), but it's not an index in the traditional sense. It's used to eliminate stripes and blocks from consideration during a scan. Columnar is not ideal for a `users` table where you want to select and update specific rows, often in very small, quick transactions (OLTP). You would want to continue to use a traditional (heap) table in that case. That's certainly something you can still do with Hydra, and combining both kinds of tables is considered HTAP, and something that is a unique use case of our product. To contrast, columnar is best for "fact" tables -- data about something that happened (thus it does not change) that will be analyzed in an aggregate way. Those might be logs, events, transactions, etc.
- winrid 4y agoClickhouse works the same way right?