Struct Config

pub struct Config {
    pub tree_type: TreeType,
    pub compression: CompressionType,
    pub blob_compression: CompressionType,
    pub data_block_size: u32,
    pub index_block_size: u32,
    pub level_count: u8,
    /* private fields */
}

Tree configuration builder

Fields

tree_type: TreeType

Tree type (unused)

compression: CompressionType

What type of compression is used

blob_compression: CompressionType

What type of compression is used for blobs

data_block_size: u32

Block size of data blocks

index_block_size: u32

Block size of index blocks

level_count: u8

Amount of levels of the LSM tree (depth of tree)

Implementations

impl Config

pub fn new<P: AsRef<Path>>(path: P) -> Self

Initializes a new config

pub fn bloom_bits_per_key(self, bits: i8) -> Self

Sets the bits per key to use for bloom filters in levels that are not L0 or L1.

Use -1 to disable bloom filters even in L0, L1, L2.

Defaults to 10 bits.

Panics

Panics if n is less than -1.

pub fn compression(self, compression: CompressionType) -> Self

Sets the compression method.

Using some compression is recommended.

Default = None

pub fn blob_compression(self, compression: CompressionType) -> Self

Sets the compression method.

Using some compression is recommended.

Default = None

pub fn level_count(self, n: u8) -> Self

Sets the amount of levels of the LSM tree (depth of tree).

Defaults to 7, like LevelDB and RocksDB.

Cannot be changed once set.

Panics

Panics if n is 0.

pub fn data_block_size(self, block_size: u32) -> Self

Sets the data block size.

Defaults to 4 KiB (4096 bytes).

For point read heavy workloads (get) a sensible default is somewhere between 4 - 8 KiB, depending on the average value size.

For scan heavy workloads (range, prefix), use 16 - 64 KiB which also increases compression efficiency.

Panics

Panics if the block size is smaller than 1 KiB or larger than 512 KiB.

pub fn index_block_size(self, block_size: u32) -> Self

Sets the index block size.

Defaults to 4 KiB (4096 bytes).

For point read heavy workloads (get) a sensible default is somewhere between 4 - 8 KiB, depending on the average value size.

For scan heavy workloads (range, prefix), use 16 - 64 KiB which also increases compression efficiency.

Panics

Panics if the block size is smaller than 1 KiB or larger than 512 KiB.

pub fn use_cache(self, cache: Arc<Cache>) -> Self

Sets the global cache.

You can create a global Cache and share it between multiple trees to cap global cache memory usage.

Defaults to a cache with 8 MiB of capacity per tree.

pub fn blob_file_target_size(self, bytes: u64) -> Self

Sets the target size of blob files.

Smaller blob files allow more granular garbage collection which allows lower space amp for lower write I/O cost.

Larger blob files decrease the number of files on disk and maintenance overhead.

Defaults to 64 MiB.

This option has no effect when not used for opening a blob tree.

pub fn blob_file_separation_threshold(self, bytes: u32) -> Self

Sets the key-value separation threshold in bytes.

Smaller value will reduce compaction overhead and thus write amplification, at the cost of lower read performance.

Defaults to 4KiB.

This option has no effect when not used for opening a blob tree.

pub fn open(self) -> Result<Tree>

Opens a tree using the config.

Errors

Will return Err if an IO error occurs.

pub fn open_as_blob_tree(self) -> Result<BlobTree>

Opens a blob tree using the config.

Errors

Will return Err if an IO error occurs.

Trait Implementations

impl Clone for Config

fn clone(&self) -> Config

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for Config

fn default() -> Self

Returns the “default value” for a type.