Struct IndexMetadata 

pub struct IndexMetadata {
    pub uuid: Option<Uuid>,
    pub fields: Vec<i32>,
    pub name: String,
    pub dataset_version: u64,
    pub fragment_bitmap: Vec<u8>,
    pub index_details: Option<Any>,
    pub index_version: Option<i32>,
    pub created_at: Option<u64>,
    pub base_id: Option<u32>,
    pub files: Vec<IndexFile>,
    pub covering_fields: Vec<i32>,
}

Metadata describing an index.

Fields

uuid: Option<Uuid>

Unique ID of an index. It is unique across all the dataset versions.

fields: Vec<i32>

The columns to build the index. These refer to file.Field.id.

fields[0] is always a column the index is keyed on. Trailing entries may instead be merely carried, not keyed on – see covering_fields below.

name: String

Index name. Must be unique within one dataset version.

dataset_version: u64

The version of the dataset this index was built from.

fragment_bitmap: Vec<u8>

A bitmap of the included fragment ids.

This may by used to determine how much of the dataset is covered by the index. This information can be retrieved from the dataset by looking at the dataset at dataset_version. However, since the old version may be deleted while the index is still in use, this information is also stored in the index.

The bitmap is stored as a 32-bit Roaring bitmap.

index_details: Option<Any>

Details, specific to the index type, which are needed to load / interpret the index

Indices should avoid putting large amounts of information in this field, as it will bloat the manifest.

Indexes are plugins, and so the format of the details message is flexible and not fully defined by the table format. However, there are some conventions that should be followed:

• When Lance APIs refer to indexes they will use the type URL of the index details as the identifier for the index type. If a user provides a simple string identifier like “btree” then it will be converted to “/lance.table.BTreeIndexDetails”
• Type URLs comparisons are case-insensitive. Thereform an index must have a unique type URL ignoring case.

index_version: Option<i32>

The minimum lance version that this index is compatible with.

created_at: Option<u64>

Timestamp when the index was created (UTC timestamp in milliseconds since epoch)

This field is optional for backward compatibility. For existing indices created before this field was added, this will be None/null.

base_id: Option<u32>

The base path index of the data file. Used when the file is imported or referred from another dataset. Lance use it as key of the base_paths field in Manifest to determine the actual base path of the data file.

files: Vec<IndexFile>

List of files and their sizes for this index segment. This enables skipping HEAD calls when opening indices and allows reporting of index sizes without extra IO. If this is empty, the index files sizes are unknown.

covering_fields: Vec<i32>

The subset of fields whose values this index co-locates alongside its own data, so a query projecting only those columns can be answered from the index without a take against the base table.

Must be a suffix of fields: the columns the index is keyed on come first, the columns it merely carries come last, and at least one keyed column always remains. Empty for an index that carries no extra columns, which is every index written before this field existed.

Carried columns are listed in fields as well. That is deliberate: every consumer that reads fields as the index’s dependency set – staleness, commit conflict detection, schema evolution guards – then covers them with no change and no way to forget one.

This declaration is not authoritative for what the segment can actually serve. The segment’s own storage schema is: a reader must confirm the storage carries a column before answering a query from it, and fall back to a take against the base table otherwise. A declaration naming columns the storage does not hold is a legal state, not corruption – a maintenance operation that cannot carry the values through a rebuild is permitted to withdraw the payload while leaving this declaration in place.

Implementations

impl IndexMetadata

pub fn index_version(&self) -> i32

Returns the value of index_version, or the default value if index_version is unset.

pub fn created_at(&self) -> u64

Returns the value of created_at, or the default value if created_at is unset.

pub fn base_id(&self) -> u32

Returns the value of base_id, or the default value if base_id is unset.

Trait Implementations

impl Clone for IndexMetadata

fn clone(&self) -> IndexMetadata

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for IndexMetadata

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

Formats the value using the given formatter.

impl Default for IndexMetadata

fn default() -> Self

Returns the “default value” for a type.

impl Message for IndexMetadata

fn encoded_len(&self) -> usize

Returns the encoded length of the message without a length delimiter.

fn clear(&mut self)

Clears the message, resetting all fields to their default.

fn encode(&self, buf: &mut impl BufMut) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message to a buffer.

fn encode_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message to a newly allocated buffer.

fn encode_length_delimited( &self, buf: &mut impl BufMut, ) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message with a length-delimiter to a buffer.

fn encode_length_delimited_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message with a length-delimiter to a newly allocated buffer.

fn decode(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes an instance of the message from a buffer.

fn decode_length_delimited(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes a length-delimited instance of the message from the buffer.

fn merge(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes an instance of the message from a buffer, and merges it into self.

fn merge_length_delimited(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes a length-delimited instance of the message from buffer, and merges it into self.

impl PartialEq for IndexMetadata

fn eq(&self, other: &IndexMetadata) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for IndexMetadata