lsm_tree::compaction

Type Alias Levelled

Source 
pub type Levelled = Leveled;
Expand description

Alias for Leveled

Aliased Type§

struct Levelled {
    pub l0_threshold: u8,
    pub target_size: u32,
    pub level_ratio: u8,
}

Fields§

§l0_threshold: u8

When the number of segments in L0 reaches this threshold, they are merged into L1.

Default = 4

Same as level0_file_num_compaction_trigger in RocksDB.

§target_size: u32

The target segment size as disk (possibly compressed).

Default = 64 MiB

Same as target_file_size_base in RocksDB.

§level_ratio: u8

Size ratio between levels of the LSM tree (a.k.a fanout, growth rate)

This is the exponential growth of the from one. level to the next

A level target size is: max_memtable_size * level_ratio.pow(#level + 1).