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Looks interesting. From reading http://hyperdex.org http://hyperdex.org (tutorial link is not useful, find the QuickStart in the regular documentation) and cons

by jws 14y ago

Looks interesting. From reading http://hyperdex.org http://hyperdex.org (tutorial link is not useful, find the QuickStart in the regular documentation) and considering it against redis for my current project… • In a single server configuration, HyperDex is marginally faster than redis at GET and PUT. • SEARCH looks like it can be much faster on HyperDex. I don't search, but I do keep some ancillary mappings from secondary attributes to keys, I could lose that with a good SEARCH. • redis has a richer set of data types and operations, in particular I would miss the server side atomic EXEC of Lua code¹. • HyperDex uses a schema as opposed to the free form of redis. That's ok for me. I like to make rules about my data. • If you plan to go beyond "in RAM" sizes, redis won't work. • Should I be so lucky as to need multiple servers, it feels like HyperDex would scale better, but it is early days for redis clustering so that would need to be assessed at that time. • I'm not seeing a wire protocol documentation for HyperDex. I think because there must be logic in the client end for hyperspace hashing. The wire protocol is a beautiful thing if you live in a strange world of insane performance goals achieved with asynchronous threading. You can just toss the supplied libraries and write your own. It will probably take a full port to figure out if there are problems with the HyperDex API in my world. So what it comes down to is, I'm not switching now, but I like what I'm seeing and will give it a spin and be ready to move if I need to. ␄ ¹ In practice, the unprotected nature of redis means code out front anyway and I can move the logic out there, but that is nonblocking C code for me and it is a lot easier to write the logic in Lua that gets atomicity for free, plus probably faster since it doesn't have to shuttle data back and forth to my process.

rescrv 14y ago
Thanks for your time. I'm the lead dev on HyperDex, so I'd be happy to address your points. - A SEARCH is simply a mapping from secondary attributes to objects and it was designed for your use case. - We're still adding server-side atomic operations. In the future we'll definitely have richer types and operations. - Server-side exec of Lua code is definitely an interesting feature. - We've put a lot of effort into making it easy to manage a HyperDex cluster without sacrificing on the scalability or fault tolerance. When you do your assessment comparing the two systems, please let us know the outcome because we'll definitely correct any deficiencies. - The client does indeed maintain a mapping for hashing. Our design is pretty asynchronous already (from the C API), so it'd be a good idea to optimize that further. Of course, we'll eventually document the wire protocol for those who want to go further. Feel free to contact me if you have questions or need a hand.
- DEinspanjer 14y ago
  @rescrv I remember seeing some of your earlier posts about HyperDex. It continues to be an interesting project to follow. I had several questions that I didn't see covered in the docs. Would love to see them answered somewhere: 1. If you have more than f faults and the cluster shuts down, what are the ramifications? How do you start it back up and recover? What if one or more of the faulted nodes are unrecoverable? Can you easily recover the partial data? 2. Can you perform OR logic in searches? i.e. Where attribute is 'a' OR 'b'? 3. Where is the new count method documented? 4. Is it possible to add new attributes to an existing space? Add new subspaces? Remove subspaces? What is the storage/memory cost associated with subspaces? 5. Are there plans for grouping and aggregation of any sort? I've been searching for a while to find a good key/value or document store system that can provide very expressive searching in combination with grouping and aggregation to provide an analytic platform for storing documents that don't fit very well in a traditional SQL store due to complexity of the structure (nested lists, etc) or dynamic addition of attributes.
  - rescrv 14y ago
    1. In the current release it's possible to completely shutdown the cluster. You cannot just cut power, but it's relatively painless to do otherwise. Checkout http://hyperdex.org/doc/06.faults/#shutting-down-and-restoring-a-cluster http://hyperdex.org/doc/06.faults/#shutting-down-and-restori... for more details. 2. Currently you cannot perform OR logic in searches. It'd be relatively easy to add though, so we'll probably do so in the future. It's possible to do two searches concurrently and combine the results. 3. This is an oversight on our part. We have to document it. In the Python bindings, you call it the same way as a regular search, but instead of getting a generator that yields objects, you simply get a number. 4. Currently, things are pretty static. We've got ideas for changing that, but just haven't pursued it yet. Each subspace replicates the data again. The memory cost of a subspace is nearly nothing (just a list of replicas). 5. I think that one-level group-by might be achievable, similar to our sorted_search primitive. There's a lot of research that people have done on this topic, and it's very interesting. That being said, the simple/straightforward approach would probably be what we'd take. Thanks for following the project!
- 14y ago

by jws 14y ago

rescrv 14y ago

Thanks for your time. I'm the lead dev on HyperDex, so I'd be happy to address your points. - A SEARCH is simply a mapping from secondary attributes to objects and it was designed for your use case. - We're still adding server-side atomic operations. In the future we'll definitely have richer types and operations. - Server-side exec of Lua code is definitely an interesting feature. - We've put a lot of effort into making it easy to manage a HyperDex cluster without sacrificing on the scalability or fault tolerance. When you do your assessment comparing the two systems, please let us know the outcome because we'll definitely correct any deficiencies. - The client does indeed maintain a mapping for hashing. Our design is pretty asynchronous already (from the C API), so it'd be a good idea to optimize that further. Of course, we'll eventually document the wire protocol for those who want to go further. Feel free to contact me if you have questions or need a hand.

DEinspanjer 14y ago
@rescrv I remember seeing some of your earlier posts about HyperDex. It continues to be an interesting project to follow. I had several questions that I didn't see covered in the docs. Would love to see them answered somewhere: 1. If you have more than f faults and the cluster shuts down, what are the ramifications? How do you start it back up and recover? What if one or more of the faulted nodes are unrecoverable? Can you easily recover the partial data? 2. Can you perform OR logic in searches? i.e. Where attribute is 'a' OR 'b'? 3. Where is the new count method documented? 4. Is it possible to add new attributes to an existing space? Add new subspaces? Remove subspaces? What is the storage/memory cost associated with subspaces? 5. Are there plans for grouping and aggregation of any sort? I've been searching for a while to find a good key/value or document store system that can provide very expressive searching in combination with grouping and aggregation to provide an analytic platform for storing documents that don't fit very well in a traditional SQL store due to complexity of the structure (nested lists, etc) or dynamic addition of attributes.
- rescrv 14y ago
  1. In the current release it's possible to completely shutdown the cluster. You cannot just cut power, but it's relatively painless to do otherwise. Checkout http://hyperdex.org/doc/06.faults/#shutting-down-and-restoring-a-cluster http://hyperdex.org/doc/06.faults/#shutting-down-and-restori... for more details. 2. Currently you cannot perform OR logic in searches. It'd be relatively easy to add though, so we'll probably do so in the future. It's possible to do two searches concurrently and combine the results. 3. This is an oversight on our part. We have to document it. In the Python bindings, you call it the same way as a regular search, but instead of getting a generator that yields objects, you simply get a number. 4. Currently, things are pretty static. We've got ideas for changing that, but just haven't pursued it yet. Each subspace replicates the data again. The memory cost of a subspace is nearly nothing (just a list of replicas). 5. I think that one-level group-by might be achievable, similar to our sorted_search primitive. There's a lot of research that people have done on this topic, and it's very interesting. That being said, the simple/straightforward approach would probably be what we'd take. Thanks for following the project!
14y ago