For PostgreSQL >= 9.4 use `gen_random_uuid()` #25395

yawboakye · 2016-06-13T21:11:38Z

Since version 9.4, the PostgreSQL community recommends moving away from
uuid-ossp's UUID generation functions and using pcrypto's
gen_random_uuid() instead. It generates UUID version 4 by default,
which is what everyone tends to use by the way.

These changes use the appropriate UUID function depending on the
underlying PostgreSQL server's version, while maintaining
uuid_generate_v4() in older migrations.

rails-bot · 2016-06-13T21:11:41Z

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rafaelfranca · 2016-06-13T21:16:45Z

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        #
        # Note that setting the UUID primary key default value to +nil+ will
        # require you to assure that you always provide a UUID value before saving
        # a record (as primary keys cannot be +nil+). This might be done via the
        # +SecureRandom.uuid+ method and a +before_save+ callback, for instance.
        def primary_key(name, type = :primary_key, **options)
-          options[:default] = options.fetch(:default, 'uuid_generate_v4()') if type == :uuid
+          if type == :uuid
+            uuid_function = ActiveRecord::Base.connection.supports_pgcrypto_uuid? ? 'gen_random_uuid()' : 'uuid_generate_v4()'


This should be using the connection that it already hold instead of ActiveRecord::Base. Could you change it?

@rafaelfranca Help me out. I can't find which connection to use :(

Seems TableDefinition doesn't have access to a connection. So we should remove the connection check here and pick gen_random_uuid as default. Using ActiveRecord::Base.connection will make this code not support multi connections.

How will that work for users on PostgreSQL 9.3 or lower since gen_random_uuid() is not available to them? Will 9.4 be the minimum required version?

They will have to explicitly tell that they want to use uuid_generate_v4(). I think it is a fair trade off and since it is documented in the changelog users will know it.

rafaelfranca · 2016-06-13T22:13:48Z

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+    else
+      def test_schema_dumper_for_uuid_primary_key
+        schema = dump_table_schema "pg_uuids"
+        assert_match(/\bcreate_table "pg_uuids", id: :uuid, default: -> { "uuid_generate_v4\(\)" }/, schema)


why is this uuid_generate_v4 not uuid_generate_v1?

Two different columns. The id column, also the primary key, uses the uuid_generate_v1() function while other_uuid uses uuid_generate_v4(). Both are functions in the uuid-ossp extension.

Yeah, but in this test if is using uuid_generate_v4 while in the test above (that should be the same test of this) is using uuid_generate_v1

Thanks for pointing it out. Turns out that test isn't necessary. The test for using gen_random_uuid() when no default is set is done using the pg_uuids_3 table instead.

kamipo · 2016-06-13T23:06:51Z

Duplicate to #21327.

yawboakye · 2016-06-14T14:07:20Z

@kamipo Yes. This PR started life as corrections to @y-yagi's original.

ianks · 2016-06-30T03:44:16Z

@yawboakye Would it be possible to include some information about migrating from uuid-ossp to gen_random_uuid()?

senny · 2016-07-19T06:15:05Z

@ianks I don't think we need to cover migration issues. This is a guide about Active Record not the PostgreSQL database. We should just make sure that we encourage best practices in our examples.

yawboakye · 2016-07-19T07:26:37Z

@senny As this will be my first contribution to Rails, I want to see it through. So please provide feedback and comments to help me improve it. Thanks cc/ @rafaelfranca @maclover7

rafaelfranca · 2016-07-20T01:27:02Z

r? @senny

senny · 2016-07-20T06:37:01Z

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@@ -9,6 +9,10 @@ def connection
  def drop_table(name)
    connection.drop_table name, if_exists: true
  end
+
+  def uuid_function
+    connection.supports_pgcrypto_uuid? ? 'gen_random_uuid()' : 'uuid_generate_v4()'


Wouldn't this mean that upgrading the PG database would case migrations to generate a different result? This might be unexpected at times.

Using a configuration option that's set in an initializer could do the trick. Quite a bit of work for a simple change like this though.

@matthewd any thoughts how we could make this less intrusive?

This is just the test, so it seems fine

matthewd · 2016-08-22T22:39:54Z

activerecord/lib/active_record/migration/compatibility.rb

+            if options[:id] == :uuid && !options[:default]
+              options[:default] = "uuid_generate_v4()"
+            end
+          end


This needs to be in V5_0

kamipo · 2016-08-23T01:13:00Z

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+*   For PostgreSQL >= 9.4 use `pgcrypto`'s `gen_random_uuid()` instead of
+    `uuid-ossp`'s UUID generation function.
+
+    *Yaw Boakye*


The original of this PR is #21327. I think that it should be credited the original author.

*Yuji Yaginuma*, *Yaw Boakye*

Since 9.4, PostgreSQL recommends using `pgcrypto`'s `gen_random_uuid()` to generate version 4 UUIDs instead of the functions in the `uuid-ossp` extension. These changes uses the appropriate UUID function depending on the underlying PostgreSQL server's version, while maintaining `uuid_generate_v4()` in older migrations.

yawboakye · 2016-11-23T11:18:27Z

@matthewd Hi Matt, looks like we're good to go! 😄

matthewd · 2016-11-24T00:37:15Z

🎉

❤️❤️

prathamesh-sonpatki · 2016-11-24T09:31:25Z

activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb

        #
        # Note that setting the UUID primary key default value to +nil+ will
        # require you to assure that you always provide a UUID value before saving
        # a record (as primary keys cannot be +nil+). This might be done via the
        # +SecureRandom.uuid+ method and a +before_save+ callback, for instance.
        def primary_key(name, type = :primary_key, **options)
-          options[:default] = options.fetch(:default, "uuid_generate_v4()") if type == :uuid
+          options[:default] = options.fetch(:default, "gen_random_uuid()") if type == :uuid


Shouldn't this check supports_pgcrypto_uuid? and then decide whether to use gen_random_uuid or uuid_generate_v4?

nevermind, I got confused by PR description but checked comment by Rafael.

- Mentioned clearly that for PostgreSQL < 9.4, you need to pass the default option with "uuid_generate_v4()" - Also updated PostgreSQL Active Record guide with this change. - rails#25395 (comment)

Follow up to rails#25395.

jcraigk · 2016-12-07T22:23:58Z

activerecord/test/cases/adapters/postgresql/uuid_test.rb

+      ensure
+        drop_table "pg_uuids_4"
+      end
+    else


Unnecessary else?

Removed at #27170.

UUID primary key with no default value feature (rails#10404, rails#18206) was lost in legacy migration caused by rails#25395 got merged. Restore the feature again in legacy migration.

Lewiscowles1986 · 2019-06-28T08:57:18Z

Is there a way to override this behaviour? It's a problem

local dev we have to enable the extension if we use postgres > 9.4
deploying to RDS we don't want our application user to be able to enable and disable extensions or know about root credentials

I'm trying (perhaps naively) to force using the uuid_generate_v4() which seems to be available for all databases we use

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use gen_random_uuid() function from pgcrypto extension in default of uuid primary key (only PostgreSQL >= 9.4) #21327

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activerecord/lib/active_record/migration/compatibility.rb

if options[:id] == :uuid && !options[:default]

options[:default] = "uuid_generate_v4()"

end

end

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matthewd Aug 22, 2016
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This needs to be in V5_0

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yawboakye force-pushed the yawboakye:use_gen_random_uuid_from_pgcrypto_extension branch to b915b11 Nov 22, 2016

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yawboakye reopened this Nov 23, 2016

rafaelfranca merged commit 8556ab5 into rails:master Nov 23, 2016
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Followup of UUID default extension in the docs #27165

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Should test `test_change_column_default` in `PostgresqlUUIDTest`

e683950

Follow up to rails#25395.

kamipo mentioned this pull request Nov 24, 2016

Should test test_change_column_default in PostgresqlUUIDTest #27172

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compatibility of default uuid generating with postgresql extension #26639

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activerecord/test/cases/adapters/postgresql/uuid_test.rb

ensure

drop_table "pg_uuids_4"

end

else

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jcraigk Dec 7, 2016

Unnecessary else?

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Removed at #27170.

kamipo mentioned this pull request Jan 9, 2017

Fix UUID primary key with default nil in legacy migration #27618

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eugeneius mentioned this pull request Jun 10, 2017

Allow uuid_test.rb to be loaded on all adapters #29409

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bwebster mentioned this pull request Sep 11, 2019

task/enable-pgcrypto-for-UUID-creation stitchfix/stitches#85

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For PostgreSQL >= 9.4 use `gen_random_uuid()` #25395

For PostgreSQL >= 9.4 use `gen_random_uuid()` #25395

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Lewiscowles1986 commented Jun 28, 2019

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For PostgreSQL >= 9.4 use gen_random_uuid() #25395

For PostgreSQL >= 9.4 use gen_random_uuid() #25395

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Lewiscowles1986 commented Jun 28, 2019

For PostgreSQL >= 9.4 use `gen_random_uuid()` #25395

For PostgreSQL >= 9.4 use `gen_random_uuid()` #25395

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