Hackers,
While working on an application, the need arose to be able
efficiently differentiate v4/v5 UUIDs (for use in partial indexes, among
others)
... so please find attached a trivial patch which adds the
functionality. The "uuid_version_bits()" function (from the test suite?)
seems quite a bit hackish, apart from inefficient :(
I'm not sure whether this actually would justify a version bump for
the OSSP-UUID extension ---a misnomer, BTW, since at least in all the
systems I have access to, the extension is actually linked against
libuuid from e2fsutils, but I digress --- or not, given that it doesn't
change exposed functionality.
Another matter, which I'd like to propose in a later thread, is
whether it'd be interesting to include the main UUID functionality
directly in core, with the remaining functions in ossp-uuid (just like
it is now, for backwards compatibility): Most current patterns for
distributed/sharded databases are based on using UUIDs for many PKs.
Thanks,
J.L.
diff --git a/contrib/uuid-ossp/uuid-ossp--1.1.sql b/contrib/uuid-ossp/uuid-ossp--1.1.sql
index c9cefd7360..a2eb217fd8 100644
--- a/contrib/uuid-ossp/uuid-ossp--1.1.sql
+++ b/contrib/uuid-ossp/uuid-ossp--1.1.sql
@@ -52,3 +52,8 @@ CREATE FUNCTION uuid_generate_v5(namespace uuid, name text)
RETURNS uuid
AS 'MODULE_PATHNAME', 'uuid_generate_v5'
IMMUTABLE STRICT LANGUAGE C PARALLEL SAFE;
+
+CREATE FUNCTION uuid_version(namespace uuid)
+RETURNS int4
+AS 'MODULE_PATHNAME', 'uuid_version'
+IMMUTABLE STRICT LANGUAGE C PARALLEL SAFE;
diff --git a/contrib/uuid-ossp/uuid-ossp.c b/contrib/uuid-ossp/uuid-ossp.c
index f5ae915f24..b4997281c0 100644
--- a/contrib/uuid-ossp/uuid-ossp.c
+++ b/contrib/uuid-ossp/uuid-ossp.c
@@ -122,6 +122,7 @@ PG_FUNCTION_INFO_V1(uuid_generate_v1mc);
PG_FUNCTION_INFO_V1(uuid_generate_v3);
PG_FUNCTION_INFO_V1(uuid_generate_v4);
PG_FUNCTION_INFO_V1(uuid_generate_v5);
+PG_FUNCTION_INFO_V1(uuid_version);
#ifdef HAVE_UUID_OSSP
@@ -531,3 +532,16 @@ uuid_generate_v5(PG_FUNCTION_ARGS)
VARDATA_ANY(name), VARSIZE_ANY_EXHDR(name));
#endif
}
+
+Datum
+uuid_version(PG_FUNCTION_ARGS)
+{
+ pg_uuid_t *arg = PG_GETARG_UUID_P(0);
+ dce_uuid_t uu;
+
+ /* function is marked STRICT, so arg can't be NULL */
+ memcpy(&uu,arg,UUID_LEN);
+ UUID_TO_NETWORK(uu);
+
+ PG_RETURN_INT32(uu.time_hi_and_version >> 12);
+}
diff --git a/doc/src/sgml/uuid-ossp.sgml b/doc/src/sgml/uuid-ossp.sgml
index b3b816c372..43dd565886 100644
--- a/doc/src/sgml/uuid-ossp.sgml
+++ b/doc/src/sgml/uuid-ossp.sgml
@@ -156,6 +156,22 @@ SELECT uuid_generate_v3(uuid_ns_url(), 'http://www.postgresql.org');
</tbody>
</tgroup>
</table>
+
+ <table id="uuid-ossp-info">
+ <title>Functions Returning UUID attributes</title>
+ <tgroup cols="2">
+ <tbody>
+ <row>
+ <entry><literal>uuid_version()</literal></entry>
+ <entry>
+ <para>
+ Returns the UUID version (1,3,4,5). Assumes variant 1 (RFC4122).
+ </para>
+ </entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
</sect2>
<sect2>
