[yummyfajitas]

As a happy user of ElephantDB, I'd say people are definitely too harsh. Elephantdb is awesome - my company has completely replaced HBase with ElephantDB and MaryJane (a lightweight way of putting data into hadoop that we wrote, https://github.com/stucchio/MaryJane- ).

That said, I'd love to see some code released, even if it isn't ready for primetime.

[gojomo]

Can you say anything about what made ElephantDB + MaryJane better than HBase for your workload? (Occasional batch loads that then need random reads but not random inserts?)

[yummyfajitas]

Absolutely - I need batch loads, and random reads. The term "insert" is somewhat meaningless - I have random appends and a periodic mapreduce job compiles the randomly appended data into structured data to served via ElephantDB. The structured data requires random queries. In principle, HBase should have filled my needs completely. But in practice, I couldn't make it work.

Our HBase cluster (3 boxes serving 30 human oracles, each submitting data at a rate of 1 record every 5-10 seconds) choked frequently - i.e., it stopped accepting new records. Ultimately what I had to do is have the human data go into postgres and a cron job flushed that into HBase every half hour or so.

I'll emphasize that this is probably my fault. I'm not claiming HBase doesn't scale to 30 concurrent users - clearly Facebook demonstrates it can. But I couldn't figure out how to make that happen. HBase is a complex system and I make no claim of understanding it.

ElephantDB + MaryJane are simple. There is almost nothing that can go wrong - put together they probably amount to 5000 lines of code and have as many as 10 minimally interacting configuration options. The effort required to manage them is minimal - I had EDB working flawlessly in less than a day.

HBase is an enterprise tool. It works well if you are Facebook and can put a couple of people on maintenance duty. It's overkill if you are Styloot (my stealth mode startup, currently smaller than Backtype).

[gojomo]

Thanks! So on each batched load, is the previous data rewritten with interleaved new data? Or is the key ordering such that's never necessary?

[yummyfajitas]

Each batched load has no ordering. But the data I'm loading is not the same as the data I'm reading.

The data I'm loading is stuff like tags - e.g., <itemid>\t<tagid>. In human terms, "Dress A has a ruched collar." Mapreduce can handle data like this, even when it comes unordered.

The data I'm reading is computational results based on the loaded data - e.g., an index: <tagid>\t[<itemid1>, <itemid2>, ...] (where each itemid has been tagged with tagid). E.g., "here are all the dresses with a ruched collar."

(Actually, we do considerably more than this, nor do we need Hadoop for an index. But an index is the simplest example I could give.)

The original data is very boring. It's only after aggregation and calculation that it becomes worth reading.

[omakase]

Cool, great to see you're making use of EDB. Would love to hear more about how you're using, how the transition was, etc. [e-mail].