Maysam Yabandeh caf0f53a74 Index value delta encoding (#3983) ... Summary: Given that index value is a BlockHandle, which is basically an <offset, size> pair we can apply delta encoding on the values. The first value at each index restart interval encoded the full BlockHandle but the rest encode only the size. Refer to IndexBlockIter::DecodeCurrentValue for the detail of the encoding. This reduces the index size which helps using the block cache more efficiently. The feature is enabled with using format_version 4. The feature comes with a bit of cpu overhead which should be paid back by the higher cache hits due to smaller index block size. Results with sysbench read-only using 4k blocks and using 16 index restart interval: Format 2: 19585 rocksdb read-only range=100 Format 3: 19569 rocksdb read-only range=100 Format 4: 19352 rocksdb read-only range=100 Pull Request resolved: https://github.com/facebook/rocksdb/pull/3983 Differential Revision: D8361343 Pulled By: maysamyabandeh fbshipit-source-id: f882ee082322acac32b0072e2bdbb0b5f854e651		2018-08-09 16:58:40 -07:00
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rocksdb	Index value delta encoding (#3983)	2018-08-09 16:58:40 -07:00