Module encoding 

Term encoding: every RDF term maps to a tagged 64-bit integer id.

Layout (the sign bit is always 0, so ids are positive SQLite INTEGERs):

 63 | 62..59 | 58..0
  0 |  tag   | payload (hash, or inline value)

Hashed kinds store a 59-bit xxh3 hash of a canonical key and need a row in terms. Inline kinds (canonical xsd:integer in ±2^58 and canonical xsd:boolean) carry their value in the payload, need no terms row, and — because the integer payload is offset — sort by value, so range filters on inline integers are id range scans.

Modules

numeric_type

Numeric type ranks used for SPARQL type promotion.

Structs

EncodedRows

Everything that must be written so that an encoded term can be decoded later.

TermRow

The row stored in terms for a hashed term.

TripleRow

The row stored in triple_terms for an RDF 1.2 triple term.

Enums

Tag

Term kinds, stored in the 4 tag bits.

Constants

DEFAULT_GRAPH_ID

The id of the default graph.

INT_MAX

Largest inline integer.

INT_MIN

Smallest inline integer.

INT_OFFSET

Offset applied to inline integers so that ids sort by value.

PAYLOAD_BITS

Number of bits used by the payload.

PAYLOAD_MASK

Mask selecting the payload.

Functions

blank_node_id

Encodes a blank node.

boolean_id

Builds the id of a boolean.

decode_inline

Decodes an inline id (integer, boolean) without any lookup.

decode_row

Decodes a hashed id from its terms row.

encode_literal

Encodes a literal, returning its id and (for hashed literals) the row to store.

graph_id

integer_id

Builds the id of an inline integer, if it fits.

make_quad

Builds a quad from decoded parts.

make_triple

Rebuilds a triple from its decoded components.

named_node_id

Encodes a named node.

numeric_rank

Returns the numeric type rank of a datatype, if numeric.

rdf_type_id

Well-known ids used by the planner and reasoner.

sort_key

A string whose byte order is the ORDER BY order of terms (blank nodes, IRIs, numbers by value, other literals by lexical form, triple terms by components).

subject_id

tag_of

Extracts the tag of an id.

term_id

Encodes a term without collecting rows (only the id).

timestamp

Seconds since the epoch of an xsd:dateTime or xsd:date lexical form (no timezone = UTC).

timezone_flag

For xsd:dateTime / xsd:date values: 1 if the lexical form has a timezone, else 0.

to_graph_name

Converts a decoded term into a graph name.

to_subject

Converts a decoded term into a subject.

triple_id

Id of a triple term (hash of its component ids).

value_key

A string that is equal for value-equal terms (numbers by value, dates by instant): used to compare triple terms with SPARQL = in one SQL comparison.