Revision a661c0d2085b6de1ff745eb83f056a87801985b4 authored by Maysam Yabandeh on 27 February 2019, 00:52:20 UTC, committed by Facebook Github Bot on 27 February 2019, 00:56:19 UTC
Summary: The read path includes a callback function, ReadCallback, which would eventually calls IsInSnapshot to figure if a particular seq is in the reading snapshot or not. This callback is virtual, which adds the cost of multiple virtual function call to each read. The first few checks in IsInSnapshot, however, are quite trivial and take care of majority of the cases. The patch moves those to a non-virtual function in the the parent class, ReadCallback, to lower the virtual callback cost. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5018 Differential Revision: D14226562 Pulled By: maysamyabandeh fbshipit-source-id: 6feed5b34f3b082e52092c5ef143e29b49c46b44
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DEFAULT_OPTIONS_HISTORY.md
# RocksDB default options change log
## Unreleased
* delayed_write_rate takes the rate given by rate_limiter if not specified.
## 5.2
* Change the default of delayed slowdown value to 16MB/s and further increase the L0 stop condition to 36 files.
## 5.0 (11/17/2016)
* Options::allow_concurrent_memtable_write and Options::enable_write_thread_adaptive_yield are now true by default
* Options.level0_stop_writes_trigger default value changes from 24 to 32.
## 4.8.0 (5/2/2016)
* options.max_open_files changes from 5000 to -1. It improves performance, but users need to set file descriptor limit to be large enough and watch memory usage for index and bloom filters.
* options.base_background_compactions changes from max_background_compactions to 1. When users set higher max_background_compactions but the write throughput is not high, the writes are less spiky to disks.
* options.wal_recovery_mode changes from kTolerateCorruptedTailRecords to kPointInTimeRecovery. Avoid some false positive when file system or hardware reorder the writes for file data and metadata.
## 4.7.0 (4/8/2016)
* options.write_buffer_size changes from 4MB to 64MB.
* options.target_file_size_base changes from 2MB to 64MB.
* options.max_bytes_for_level_base changes from 10MB to 256MB.
* options.soft_pending_compaction_bytes_limit changes from 0 (disabled) to 64GB.
* options.hard_pending_compaction_bytes_limit changes from 0 (disabled) to 256GB.
* table_cache_numshardbits changes from 4 to 6.
* max_file_opening_threads changes from 1 to 16.
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