Name
adler32, tridgell32, uuid, rdf_uuid_impl, rdf_struuid_impl — checksum and UUID generation helpers
Synopsis
integer adler32(
|
in data varchar); |
any tridgell32(
|
in data varchar, |
in as_integer integer); |
varchar uuid(
|
); |
IRI_ID rdf_uuid_impl(
|
); |
varchar rdf_struuid_impl(
|
); |
Description
adler32 computes the Adler-32 checksum (RFC 1950) of
its argument and returns it as an integer. The same checksum is used by
the zlib container around DEFLATE payloads.
tridgell32 computes the 32-bit rolling checksum
introduced by Andrew Tridgell for the rsync algorithm. Returned as a
string of hex digits by default; pass a non-zero second argument to return
the value as a plain integer.
uuid generates a new RFC 4122 version-4 UUID and
returns it as a 36-character lowercase string. Each call returns a fresh
value (the function is marked BMD_NO_FOLD, so the SQL
compiler does not constant-fold repeated invocations).
rdf_uuid_impl is the SPARQL UUID()
backend: it returns a fresh UUID wrapped in an IRI_ID using
the urn:uuid: scheme.
rdf_struuid_impl is the SPARQL
STRUUID() backend and the canonical alias of
uuid: it returns the same lowercase 36-character UUID
string. Documented separately because the SPARQL planner emits
rdf_struuid_impl directly.