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https://issues.apache.org/jira/browse/CASSANDRA-13553?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16023900#comment-16023900
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Dikang Gu commented on CASSANDRA-13553:
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This will include changes both in Cassandra and RocksDB, we already submitted a
PR for the rocksdb merge operator changes,
https://github.com/facebook/rocksdb/pull/2289/files
> Map C* Wide column to RocksDB key value data model
> --------------------------------------------------
>
> Key: CASSANDRA-13553
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13553
> Project: Cassandra
> Issue Type: Sub-task
> Components: Core
> Reporter: Dikang Gu
> Assignee: Dikang Gu
>
> The goal for this ticket is to find a way to map Cassandra's wide column data
> model to RocksDB's key value data model.
> To support most common C* queries on top of RocksDB, we plan to use this
> strategy, for each row in Cassandra:
> 1. Encode Cassandra partition key + clustering keys into RocksDB key.
> 2. Encode rest of Cassandra columns into RocksDB value.
> With this approach, there are two major problems we need to solve:
> 1. After we encode C* keys into RocksDB key, we need to preserve the same
> sorting order in RocksDB byte comparator, as in original data type.
> 2. Support timestamp, ttl, and tombestone on the values.
> To solve problem 1, we need to carefully design the encoding algorithm for
> each data type. Fortunately, there are some existing libraries we can play
> with, such as orderly (https://github.com/ndimiduk/orderly), which is used by
> HBase. Or flatbuffer (https://github.com/google/flatbuffers)
> To solve problem 2, our plan is to encode C* timestamp, ttl, and tombestone
> together with the values, and then use RocksDB's merge operator/compaction
> filter to merge different version of data, and handle ttl/tombestones.
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