On 2019-04-09 08:04, Peter Eisentraut wrote:
> On 2019-04-08 23:06, Andres Freund wrote:
>> The randomness based UUID generators don't really have dependencies, now
>> that we have a dependency on strong randomness. I kinda thing the
>> dependency argument actually works *against* uuid-ossp - precisely
>> because of its dependencies (which also vary by OS) it's not a proper
>> replacement for a type of facility a very sizable fraction of our users
>> need.
>
> Yeah, I think implementing a v4 generator in core would be trivial and
> address almost everyone's requirements.
Here is a proposed patch for this. I did a fair bit of looking around
in other systems for a naming pattern but didn't find anything
consistent. So I ended up just taking the function name and code from
pgcrypto.
As you can see, the code is trivial and has no external dependencies. I
think this would significantly upgrade the usability of the uuid type.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
From dec1949a482ae425527987a43d28c8b26ba1e0ed Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pe...@eisentraut.org>
Date: Tue, 4 Jun 2019 09:00:31 +0200
Subject: [PATCH] Add gen_random_uuid function
---
doc/src/sgml/datatype.sgml | 12 ++---------
doc/src/sgml/func.sgml | 26 ++++++++++++++++++++++++
doc/src/sgml/pgcrypto.sgml | 3 ++-
doc/src/sgml/uuid-ossp.sgml | 11 +++-------
src/backend/utils/adt/uuid.c | 20 ++++++++++++++++++
src/include/catalog/pg_proc.dat | 3 +++
src/test/regress/expected/opr_sanity.out | 1 +
src/test/regress/expected/uuid.out | 10 +++++++++
src/test/regress/sql/uuid.sql | 6 ++++++
9 files changed, 73 insertions(+), 19 deletions(-)
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index fc300f605f..809d98036c 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -4175,16 +4175,8 @@ <title><acronym>UUID</acronym> Type</title>
</para>
<para>
- <productname>PostgreSQL</productname> provides storage and comparison
- functions for UUIDs, but the core database does not include any
- function for generating UUIDs, because no single algorithm is well
- suited for every application. The <xref
- linkend="uuid-ossp"/> module
- provides functions that implement several standard algorithms.
- The <xref linkend="pgcrypto"/> module also provides a generation
- function for random UUIDs.
- Alternatively, UUIDs could be generated by client applications or
- other libraries invoked through a server-side function.
+ See <xref linkend="functions-uuid"/> for how to generate a UUID in
+ <productname>PostgreSQL</productname>.
</para>
</sect1>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index a79e7c0380..b6caaf6b9b 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -10291,6 +10291,32 @@ <title>Text Search Debugging Functions</title>
</sect1>
+ <sect1 id="functions-uuid">
+ <title>UUID Functions</title>
+
+ <indexterm zone="datatype-uuid">
+ <primary>UUID</primary>
+ <secondary>generating</secondary>
+ </indexterm>
+
+ <indexterm>
+ <primary>gen_random_uuid</primary>
+ </indexterm>
+
+ <para>
+ <productname>PostgreSQL</productname> includes one function to generate a
UUID:
+<synopsis>
+gen_random_uuid() returns uuid
+</synopsis>
+ This function returns a version 4 (random) UUID. This is the most commonly
+ used type of UUID and is appropriate for most applications.
+ </para>
+
+ <para>
+ The <xref linkend="uuid-ossp"/> module provides additional functions that
+ implement other standard algorithms for generating UUIDs.
+ </para>
+ </sect1>
<sect1 id="functions-xml">
diff --git a/doc/src/sgml/pgcrypto.sgml b/doc/src/sgml/pgcrypto.sgml
index 5c79666654..0acd11ed55 100644
--- a/doc/src/sgml/pgcrypto.sgml
+++ b/doc/src/sgml/pgcrypto.sgml
@@ -1132,7 +1132,8 @@ <title>Random-Data Functions</title>
gen_random_uuid() returns uuid
</synopsis>
<para>
- Returns a version 4 (random) UUID.
+ Returns a version 4 (random) UUID. (Obsolete, this function is now also
+ included in core <productname>PostgreSQL</productname>.)
</para>
</sect2>
diff --git a/doc/src/sgml/uuid-ossp.sgml b/doc/src/sgml/uuid-ossp.sgml
index b3b816c372..0fbabbfda2 100644
--- a/doc/src/sgml/uuid-ossp.sgml
+++ b/doc/src/sgml/uuid-ossp.sgml
@@ -11,6 +11,9 @@ <title>uuid-ossp</title>
The <filename>uuid-ossp</filename> module provides functions to generate
universally
unique identifiers (UUIDs) using one of several standard algorithms. There
are also functions to produce certain special UUID constants.
+ This module is only necessary for special requirements beyond what is
+ available in core <productname>PostgreSQL</productname>. See <xref
+ linkend="functions-uuid"/> for built-in ways to generate UUIDs.
</para>
<sect2>
@@ -181,14 +184,6 @@ <title>Building <filename>uuid-ossp</filename></title>
More than one of these libraries might be available on a particular
machine, so <filename>configure</filename> does not automatically choose
one.
</para>
-
- <note>
- <para>
- If you only need randomly-generated (version 4) UUIDs,
- consider using the <function>gen_random_uuid()</function> function
- from the <xref linkend="pgcrypto"/> module instead.
- </para>
- </note>
</sect2>
<sect2>
diff --git a/src/backend/utils/adt/uuid.c b/src/backend/utils/adt/uuid.c
index 09aa6b6daa..589c2d51dd 100644
--- a/src/backend/utils/adt/uuid.c
+++ b/src/backend/utils/adt/uuid.c
@@ -416,3 +416,23 @@ uuid_hash_extended(PG_FUNCTION_ARGS)
return hash_any_extended(key->data, UUID_LEN, PG_GETARG_INT64(1));
}
+
+Datum
+gen_random_uuid(PG_FUNCTION_ARGS)
+{
+ pg_uuid_t *uuid = palloc(UUID_LEN);
+
+ if (!pg_strong_random(uuid, UUID_LEN))
+ ereport(ERROR,
+ (errcode(ERRCODE_INTERNAL_ERROR),
+ errmsg("could not generate random values")));
+
+ /*
+ * Set magic numbers for a "version 4" (pseudorandom) UUID, see
+ * http://tools.ietf.org/html/rfc4122#section-4.4
+ */
+ uuid->data[6] = (uuid->data[6] & 0x0f) | 0x40; /* time_hi_and_version
*/
+ uuid->data[8] = (uuid->data[8] & 0x3f) | 0x80; /*
clock_seq_hi_and_reserved */
+
+ PG_RETURN_UUID_P(uuid);
+}
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 87335248a0..8ecf379955 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -8341,6 +8341,9 @@
{ oid => '3412', descr => 'hash',
proname => 'uuid_hash_extended', prorettype => 'int8',
proargtypes => 'uuid int8', prosrc => 'uuid_hash_extended' },
+{ oid => '3429', descr => 'generate random UUID',
+ proname => 'gen_random_uuid', proleakproof => 't', prorettype => 'uuid',
+ proargtypes => '', prosrc => 'gen_random_uuid' },
# pg_lsn
{ oid => '3229', descr => 'I/O',
diff --git a/src/test/regress/expected/opr_sanity.out
b/src/test/regress/expected/opr_sanity.out
index 85af36ee5b..33c058ff51 100644
--- a/src/test/regress/expected/opr_sanity.out
+++ b/src/test/regress/expected/opr_sanity.out
@@ -742,6 +742,7 @@ sha224(bytea)
sha256(bytea)
sha384(bytea)
sha512(bytea)
+gen_random_uuid()
starts_with(text,text)
macaddr8_eq(macaddr8,macaddr8)
macaddr8_lt(macaddr8,macaddr8)
diff --git a/src/test/regress/expected/uuid.out
b/src/test/regress/expected/uuid.out
index db66dc723e..090103df48 100644
--- a/src/test/regress/expected/uuid.out
+++ b/src/test/regress/expected/uuid.out
@@ -145,5 +145,15 @@ SELECT COUNT(*) FROM guid1 g1 LEFT JOIN guid2 g2 ON
g1.guid_field = g2.guid_fiel
1
(1 row)
+-- generation test
+TRUNCATE guid1;
+INSERT INTO guid1 (guid_field) VALUES (gen_random_uuid());
+INSERT INTO guid1 (guid_field) VALUES (gen_random_uuid());
+SELECT count(DISTINCT guid_field) FROM guid1;
+ count
+-------
+ 2
+(1 row)
+
-- clean up
DROP TABLE guid1, guid2 CASCADE;
diff --git a/src/test/regress/sql/uuid.sql b/src/test/regress/sql/uuid.sql
index 518d2b75c0..3bd3b357c7 100644
--- a/src/test/regress/sql/uuid.sql
+++ b/src/test/regress/sql/uuid.sql
@@ -75,5 +75,11 @@ CREATE UNIQUE INDEX guid1_unique_BTREE ON guid1 USING BTREE
(guid_field);
SELECT COUNT(*) FROM guid1 g1 INNER JOIN guid2 g2 ON g1.guid_field =
g2.guid_field;
SELECT COUNT(*) FROM guid1 g1 LEFT JOIN guid2 g2 ON g1.guid_field =
g2.guid_field WHERE g2.guid_field IS NULL;
+-- generation test
+TRUNCATE guid1;
+INSERT INTO guid1 (guid_field) VALUES (gen_random_uuid());
+INSERT INTO guid1 (guid_field) VALUES (gen_random_uuid());
+SELECT count(DISTINCT guid_field) FROM guid1;
+
-- clean up
DROP TABLE guid1, guid2 CASCADE;
--
2.21.0
