Merge branch 'bw-replication-slots-supported' into 'master'

add Gitlab::Database.replication_slots_supported?

See merge request gitlab-org/gitlab-ce!15744

lib/gitlab/database.rb

@@ -50,6 +50,10 @@ module Gitlab
       postgresql? && version.to_f >= 9.3
     end
 
+    def self.replication_slots_supported?
+      postgresql? && version.to_f >= 9.4
+    end
+
     def self.nulls_last_order(field, direction = 'ASC')
       order = "#{field} #{direction}"
 

spec/lib/gitlab/database_spec.rb

@@ -73,6 +73,28 @@ describe Gitlab::Database do
     end
   end
 
+  describe '.replication_slots_supported?' do
+    it 'returns false when using MySQL' do
+      allow(described_class).to receive(:postgresql?).and_return(false)
+
+      expect(described_class.replication_slots_supported?).to eq(false)
+    end
+
+    it 'returns false when using PostgreSQL 9.3' do
+      allow(described_class).to receive(:postgresql?).and_return(true)
+      allow(described_class).to receive(:version).and_return('9.3.1')
+
+      expect(described_class.replication_slots_supported?).to eq(false)
+    end
+
+    it 'returns true when using PostgreSQL 9.4.0 or newer' do
+      allow(described_class).to receive(:postgresql?).and_return(true)
+      allow(described_class).to receive(:version).and_return('9.4.0')
+
+      expect(described_class.replication_slots_supported?).to eq(true)
+    end
+  end
+
   describe '.nulls_last_order' do
     context 'when using PostgreSQL' do
       before do