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5f3a46eabb
"This patchset implements load_new_sstables, allowing one to move tables inside the data directory of a CF, and then call "nodetool refresh" to start using them. Keep in mind that for Cassandra, this is deemed an unsafe operation: https://issues.apache.org/jira/browse/CASSANDRA-6245 It is still for us something we should not recommend - unless the CF is totally empty and not yet used, but we can do a much better job in the safety front. To guarantee that, the process works in four steps: 1) All writes to this specific column family are disabled. This is a horrible thing to do, because dirty memory can grow much more than desired during this. Throughout out this implementation, we will try to keep the time during which the writes are disabled to its bare minimum. While disabling the writes, each shard will tell us about the highest generation number it has seen. 2) We will scan all tables that we haven't seen before. Those are any tables found in the CF datadir, that are higher than the highest generation number seen so far. We will link them to new generation numbers that are sequential to the ones we have so far, and end up with a new generation number that is returned to the next step 3) The generation number computed in the previous step is now propagated to all CFs, which guarantees that all further writes will pick generation numbers that won't conflict with the existing tables. Right after doing that, the writes are resumed. 4) The tables we found in step 2 are passed on to each of the CFs. They can now load those tables while operations to the CF proceed normally."