Cleanup checks for replication slot in Geo

This removes checking for the presence of PG
replication slots. This is not necessary anymore since that has been
supported since PG 9.4 and we're on >= PG11 now.

ee/app/models/geo_node.rb

@@ -300,19 +300,19 @@ class GeoNode < ApplicationRecord
   end
 
   def replication_slots_count
-    return unless Gitlab::Database.replication_slots_supported? && primary?
+    return unless primary?
 
     PgReplicationSlot.count
   end
 
   def replication_slots_used_count
-    return unless Gitlab::Database.replication_slots_supported? && primary?
+    return unless primary?
 
     PgReplicationSlot.used_slots_count
   end
 
   def replication_slots_max_retained_wal_bytes
-    return unless Gitlab::Database.replication_slots_supported? && primary?
+    return unless primary?
 
     PgReplicationSlot.max_retained_wal
   end

ee/spec/models/pg_replication_slot_spec.rb

@@ -3,52 +3,48 @@
 require 'spec_helper'
 
 RSpec.describe PgReplicationSlot do
-  if Gitlab::Database.replication_slots_supported?
-    describe 'with replication slot support' do
-      it '#max_replication_slots' do
-        expect(described_class.max_replication_slots).to be >= 0
-      end
+  it '#max_replication_slots' do
+    expect(described_class.max_replication_slots).to be >= 0
+  end
+
+  skip_examples = described_class.max_replication_slots <= described_class.count
+  context 'with enough slots available' do
+    before(:all) do
+      skip('max_replication_slots too small') if skip_examples
+
+      @current_slot_count =
+        ActiveRecord::Base.connection.execute("SELECT COUNT(*) FROM pg_replication_slots;")
+        .first.fetch('count').to_i
+      @current_unused_count =
+        ActiveRecord::Base.connection.execute("SELECT COUNT(*) FROM pg_replication_slots WHERE active = 'f';")
+        .first.fetch('count').to_i
 
-      skip_examples = described_class.max_replication_slots <= described_class.count
-      context 'with enough slots available' do
-        before(:all) do
-          skip('max_replication_slots too small') if skip_examples
-
-          @current_slot_count =
-            ActiveRecord::Base.connection.execute("SELECT COUNT(*) FROM pg_replication_slots;")
-            .first.fetch('count').to_i
-          @current_unused_count =
-            ActiveRecord::Base.connection.execute("SELECT COUNT(*) FROM pg_replication_slots WHERE active = 'f';")
-            .first.fetch('count').to_i
-
-          ActiveRecord::Base.connection.execute("SELECT * FROM pg_create_physical_replication_slot('test_slot');")
-        end
-
-        after(:all) do
-          unless skip_examples
-            ActiveRecord::Base.connection.execute("SELECT pg_drop_replication_slot('test_slot');")
-          end
-        end
-
-        it '#slots_count' do
-          expect(described_class.count).to eq(@current_slot_count + 1)
-        end
-
-        it '#unused_slots_count' do
-          expect(described_class.unused_slots_count).to eq(@current_unused_count + 1)
-        end
-
-        it '#max_retained_wal' do
-          expect(described_class.max_retained_wal).not_to be_nil
-        end
-
-        it '#slots_retained_bytes' do
-          slot = described_class.slots_retained_bytes.find {|x| x['slot_name'] == 'test_slot' }
-
-          expect(slot).not_to be_nil
-          expect(slot['retained_bytes']).to be_nil
-        end
+      ActiveRecord::Base.connection.execute("SELECT * FROM pg_create_physical_replication_slot('test_slot');")
+    end
+
+    after(:all) do
+      unless skip_examples
+        ActiveRecord::Base.connection.execute("SELECT pg_drop_replication_slot('test_slot');")
       end
     end
+
+    it '#slots_count' do
+      expect(described_class.count).to eq(@current_slot_count + 1)
+    end
+
+    it '#unused_slots_count' do
+      expect(described_class.unused_slots_count).to eq(@current_unused_count + 1)
+    end
+
+    it '#max_retained_wal' do
+      expect(described_class.max_retained_wal).not_to be_nil
+    end
+
+    it '#slots_retained_bytes' do
+      slot = described_class.slots_retained_bytes.find {|x| x['slot_name'] == 'test_slot' }
+
+      expect(slot).not_to be_nil
+      expect(slot['retained_bytes']).to be_nil
+    end
   end
 end

lib/gitlab/database.rb

@@ -99,10 +99,6 @@ module Gitlab
       version.to_f < 10
     end
 
-    def self.replication_slots_supported?
-      version.to_f >= 9.4
-    end
-
     def self.postgresql_minimum_supported_version?
       version.to_f >= MINIMUM_POSTGRES_VERSION
     end

spec/lib/gitlab/database_spec.rb

@@ -156,20 +156,6 @@ RSpec.describe Gitlab::Database do
     end
   end
 
-  describe '.replication_slots_supported?' do
-    it 'returns false when using PostgreSQL 9.3' do
-      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(:version).and_return('9.4.0')
-
-      expect(described_class.replication_slots_supported?).to eq(true)
-    end
-  end
-
   describe '.pg_wal_lsn_diff' do
     it 'returns old name when using PostgreSQL 9.6' do
       allow(described_class).to receive(:version).and_return('9.6')