rocksdb/docs/_posts/2017-07-25-rocksdb-5-6-1-released.markdown at 6a9335dbbb3ecc87fb1cb8701be39b3ec16beb20

title	layout	author	category
RocksDB 5.6.1 Released!	post	yiwu	blog

Scheduling flushes and compactions in the same thread pool is no longer supported by setting max_background_flushes=0. Instead, users can achieve this by configuring their high-pri thread pool to have zero threads. See https://github.com/facebook/rocksdb/wiki/Thread-Pool for more details.
Replace Options::max_background_flushes, Options::max_background_compactions, and Options::base_background_compactions all with Options::max_background_jobs, which automatically decides how many threads to allocate towards flush/compaction.
options.delayed_write_rate by default take the value of options.rate_limiter rate.
Replace global variable IOStatsContext iostats_context with IOStatsContext* get_iostats_context(); replace global variable PerfContext perf_context with PerfContext* get_perf_context().

Change ticker/histogram statistics implementations to use core-local storage. This improves aggregation speed compared to our previous thread-local approach, particularly for applications with many threads. See http://rocksdb.org/blog/2017/05/14/core-local-stats.html for more details.
Users can pass a cache object to write buffer manager, so that they can cap memory usage for memtable and block cache using one single limit.
Flush will be triggered when 7/8 of the limit introduced by write_buffer_manager or db_write_buffer_size is triggered, so that the hard threshold is hard to hit. See https://github.com/facebook/rocksdb/wiki/Write-Buffer-Manager for more details.
Introduce WriteOptions.low_pri. If it is true, low priority writes will be throttled if the compaction is behind. See https://github.com/facebook/rocksdb/wiki/Low-Priority-Write for more details.
DB::IngestExternalFile() now supports ingesting files into a database containing range deletions.