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Fetching key range with common prefix in Cassandra

开发者 https://www.devze.com 2023-03-11 21:57 出处:网络
I want to fetch all rows having a common prefix using hector API. I played with RangeSuperSlicesQuery a bit but didn\'t find a way to get it working properly. Does key range parameters work with wild

I want to fetch all rows having a common prefix using hector API. I played with RangeSuperSlicesQuery a bit but didn't find a way to get it working properly. Does key range parameters work with wild cards etc?

Update开发者_JAVA技巧: I used ByteOrderedPartitioner instead of RandomPartitioner and it works fine with that. Is this the expected behavior?


Yes, that's the expected behavior. In RandomPartitioner, rows are stored in the order of the MD5 hash of their keys, so to get a meaningful range of keys, you need to use an order preserving partitioner like ByteOrderedPartitioner.

However, there are downsides to using ByteOrderedPartitioner or OrderPreservingPartitioner that you can usually avoid with a slightly different data model and RandomPartitioner.


To elaborate on the above answer, you should consider using column names as your "common prefix" instead of the key. Then you can either use a column slice to get all column names in a certain range, or you could use a secondary index then do an indexed slice for all keys with that column name.

Column slice example:

Key (without prefix) 
  <prefix1> : <data>
  <prefix2> : <data>
  ...

Secondary index example:

Key (with or without prefix)
  "prefix" : <the_prefix> <-- this column is indexed
  otherCol1 : <data>    
  ...
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