This would add a new boolean config option: hfile.block.cache.datablocks
Default would be true.
Setting this to false allows HBase in a mode where only index blocks are cached, which is useful for analytical scenarios where a useful working set of the data cannot be expected to fit into the (aggregate) cache.
This is the equivalent of setting cacheBlocks to false on all scans (including scans on behalf of gets).
I would like to get a general feeling about what folks think about this.
The change itself would be simple.
Update (Mikhail): we probably don't need a new conf option. Instead, we will make index blocks cached by default.