Struct lsm_tree::Segment

pub struct Segment {
    pub metadata: Metadata,
    /* private fields */
}

Disk segment (a.k.a. SSTable, sorted string table) that is located on disk

A segment is an immutable list of key-value pairs, split into compressed blocks (see [block::ValueBlock]). The block offset and size in the file is saved in the “block index”.

Deleted entries are represented by tombstones.

Segments can be merged together to remove duplicates, reducing disk space and improving read performance.

Fields

metadata: Metadata

Segment metadata object (will be stored in a JSON file)

Implementations

impl Segment

pub fn recover<P: AsRef<Path>>( folder: P, block_cache: Arc<BlockCache>, descriptor_table: Arc<FileDescriptorTable> ) -> Result<Self>

Tries to recover a segment from a folder.

pub fn get<K: AsRef<[u8]>>( &self, key: K, seqno: Option<SeqNo> ) -> Result<Option<Value>>

Retrieves an item from the segment.

Errors

Will return Err if an IO error occurs.

pub fn iter(&self, use_cache: bool) -> Reader

Creates an iterator over the Segment.

Errors

Will return Err if an IO error occurs.

pub fn range(&self, range: (Bound<UserKey>, Bound<UserKey>)) -> Range

Creates a ranged iterator over the Segment.

Errors

Will return Err if an IO error occurs.

pub fn prefix<K: Into<UserKey>>(&self, prefix: K) -> PrefixedReader

Creates a prefixed iterator over the Segment.

Errors

Will return Err if an IO error occurs.

pub fn get_lsn(&self) -> SeqNo

Returns the highest sequence number in the segment.

pub fn tombstone_count(&self) -> u64

Returns the amount of tombstone markers in the Segment.

Trait Implementations

impl Debug for Segment

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.