[infinispan-issues] [JBoss JIRA] (ISPN-12011) Investigate CompactionFilter for purging expired entries in RocksDB

[Dan Berindei (Jira)]

Dan Berindei created ISPN-12011:
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             Summary: Investigate CompactionFilter for purging expired entries in RocksDB
                 Key: ISPN-12011
                 URL: https://issues.redhat.com/browse/ISPN-12011
             Project: Infinispan
          Issue Type: Sub-task
          Components: Loaders and Stores
            Reporter: Dan Berindei
             Fix For: 12.0.0.Final


RocksDB allows the application to process/delete entries during compaction, and we could use this {{}}[CompactionFilter|https://github.com/facebook/rocksdb/blob/master/include/rocksdb/compaction_filter.h] callback to implement the purging of expired entries.

It's not straightforward, through: {{CompactionFilter}} must be implemented in a native (C++) library. {{rocksdb-jni}} allows using a native implementation from Java, but it does not allow defining it in Java (like it does for comparators).

Potential solutions:
 # Write a native library implementing {{CompactionFilter}} for our current storage format
 # Change the value format to match the Cassandra storage format and use the predefined {{CassandraCompactionFilter}} 
 # Revive the now-removed [LuaCompactionFilter|https://github.com/facebook/rocksdb/wiki/Lua-CompactionFilter] and write our filter implementation in Lua
 # Contribute an adapter for Java CompactionFilter implementations to the RocksDB project, inspired by the existing AbstractComparator



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