参数

说明

备注

writebuffer_size

memtable内存大小

默认

max_write_buffer_number

memtable的最大个数

默认2

min_write_buffer_number_to_merge

it is the minimum number of memtables to be merged before flushing to storage. For example, if this option is set to 2, immutable memtables are only flushed when there are two of them

默认1

target_file_size_base

level1 sst大小

默认64M

target_file_size_multiplier

level L(L>1) sst大小

target_file_size_base (target_file_size_multiplier ^ (L-1))

默认1，

For example, if target_file_size_base is 2MB and
target_file_size_multiplier is 10, then each file on level-1 will
be 2MB, and each file on level-2 will be 20MB,
and each file on level-3 will be 200MB

max_bytes_for_level_base

level1的sst总大小

默认256M

max_bytes_for_level_multiplier

level L的sst总大小为 max_bytes_for_level_base(max_bytes_for_level_multiplier)^(L-1))*max_bytes_for_level_multiplier_additional(L-1)

(VersionStorageInfo::CalculateBaseBytes)

默认10

max_bytes_for_level_multiplier_additional

Different max-size multipliers for different levels.

(VersionStorageInfo::CalculateBaseBytes)

默认：1:1:1:1:1:1:1

num_levels

level数量

默认7

level0_file_num_compaction_trigger

当level0文件数量超过此值时触发level0 compact

默认4

level0_slowdown_writes_trigger

当level0文件数量超过此值时触发x写delay

默认20

level0_stop_writes_trigger

当level0文件数量超过此值时触发停写

默认36

pin_l0_filter_and_index_blocks_in_cache

if cache_index_and_filter_blocks is true and the below is true, then filter and index blocks are stored in the cache, but a reference is held in the “table reader” object so the blocks are pinned and only evicted from cache when the table reader is freed.

默认1，

column family单独设置会覆盖rocksdb_pin_l0_filter_and_index_blocks_in_cache

cache_index_and_filter_blocks

index和filter blocks是否缓存到block cache

默认1，

column family单独设置会覆盖rocksdb_cache_index_and_filter_blocks

optimize_filters_for_hits

设置为True， 最后一层不保存filter信息，最后一层bloomfilter实际没有用处

默认OFF

filter_policy

指定filter策略

filter_policy=bloomfilter:10:false

表示使用bloomfilter,

bits_per_key=10, hash函数个数为10*ln2，

false：useblock_based_builder=false，表示使用full filter

prefixextractor

指定filter使用前缀

prefix_extractor=capped:24表示最多取前缀24个字节，另外还有fixed:n方式表示只取前缀n个字节，忽略小于n个字节的key. 具体可参考CappedPrefixTransform，FixedPrefixTransform

partition_filters

表示时否使用partitioned filter

默认false

filter 参数优先级如下 block base > partitioned > full. 比如说同时指定use_block_based_builder=true和partition_filters=true实际使用的block based filter

whole_key_filtering

If true, place whole keys in the filter (not just prefixes)

默认1

level_compaction_dynamic_level_bytes

In this mode, size target of levels are changed dynamically based on size of the last level.

减少写放大

memtable

指定memtable类型(skiplist/vector/hash_linkedlist/prefix_hash/cuckoo)

默认skiplist

compaction_pri

compact选择文件策略

kByCompensatedSize：

Slightly prioritize larger files by size compensated by #deletes

kOldestLargestSeqFirst：

First compact files whose data’s latest update time is oldest

kOldestSmallestSeqFirst：

First compact files whose range hasn’t been compacted to the next level for the longest

kMinOverlappingRatio：

First compact files whose ratio between overlapping size in next level and its size is the smallest

默认kByCompensatedSize

compression_per_level

指定每个level的压缩策略

It usually makes sense to avoid compressing levels 0 and 1 and to compress data only in higher levels. You can even set slower compression in highest level and faster compression in lower levels (by highest we mean Lmax).

bottommost_compression

指定最底level的压缩策略

arena_block_size

rocksdb内存分配单位KBlockSize由参数arena_block_size指定

arena_block_size不指定时默认为write_buffer_size的1/8.

soft_pending_compaction_bytes_limit

All writes will be slowed down to at least delayed_write_rate if estimated
bytes needed to be compaction exceed this threshold

默认64G

hard_pending_compaction_bytes_limit

All writes are stopped if estimated bytes needed to be compaction exceed this threshold.

默认256G