LevelDB 不存在的特性

Multithread compaction 多线程 compaction压缩
Multithread memtable inserts 多线程memtable插入
Reduced DB mutex holding 减少 DB互斥锁的持有
Optimized level-based compaction style and universal compaction style 优化的分级压缩方式和通用压缩方式
Prefix bloom filter 前缀Bloom过滤器
Memtable bloom filter MemtableBloom过滤器
Single bloom filter covering the whole SST file 单Bloom过滤器覆盖整个SST文件
Write lock optimization 写锁优化
Improved Iter::Prev() performance 改进Iter::Prev()性能
Fewer comparator calls during SkipList searches 在SkipList跳表搜索期间，比较器调用更少
Allocate memtable memory using huge page. 使用大页面分配内存。

Rate limiting 速度限制
Tunable Slowdown and Stop threshold 可调减速和停止阈值
Option to keep all files open 保留所有文件打开的选项
Option to keep all index and bloom filter blocks in block cache 选项可将所有索引和bloom过滤器块保存在块缓存中
Multiple WAL recovery modes 多种WAL恢复模式
Fadvise hints for readahead and to avoid caching in OS page cache Fadvise提示提前读取，避免在OS页面缓存中缓存
Option to pin indexes and bloom filters of L0 files in memory 选择将L0文件的索引和Bloom过滤器固定在内存中
More Compression Types: zlib, lz4, zstd 更多压缩类型:zlib, lz4, zstd
Compression Dictionary 压缩字典
Checksum Type: xxhash 校验和类型:xxhash
Different level size multiplier and compression type for each level. 每个级别的级别大小乘法器和压缩类型不同。