Make sure PostgreSQL and MySQL give the same resultgitlab-connection-pool

This might go too far by using `ActiveRecord::AttributeSet::Builder`
but unfortunately that's how Rails is doing that to unify the results
from different database adapters. I don't know why it's built into
the model so tightly while it could just stay as in connection.

2 files changed, 20 insertions, 8 deletions

diff --git a/lib/gitlab/database/connection_pool.rb b/lib/gitlab/database/connection_pool.rb
index 7cc1604559c..fb4c55a8ac0 100644
--- a/lib/gitlab/database/connection_pool.rb
+++ b/lib/gitlab/database/connection_pool.rb
@@ -23,11 +23,13 @@ module Gitlab
         @ar_pool.spec.config[:pool]
       end
 
-      def execute_async(sql)
+      # Pass `method: :exec_query` if we want unified result from query
+      # across PostgreSQL and MySQL
+      def execute_async(sql, method: :execute)
         @mutex.synchronize do
           @workers << Thread.new do
             @ar_pool.with_connection do |connection|
-              connection.execute(sql)
+              connection.public_send(method, sql)
             end
           end
         end
diff --git a/spec/lib/gitlab/database/connection_pool_spec.rb b/spec/lib/gitlab/database/connection_pool_spec.rb
index a137a3eeb2d..2e3c6a23571 100644
--- a/spec/lib/gitlab/database/connection_pool_spec.rb
+++ b/spec/lib/gitlab/database/connection_pool_spec.rb
@@ -52,27 +52,28 @@ describe Gitlab::Database::ConnectionPool, lib: true do
 
   describe '#execute_async' do
     it 'runs the right query' do
-      subject.execute_async('SELECT 1+2 AS value;')
+      subject.execute_async('SELECT 1+2 AS value;', method: :exec_query)
+      result = convert_result_to_hash(subject.join)
 
-      expect(subject.join.map(&:to_a)).to eq([[{ 'value' => '3' }]])
+      expect(result).to eq([[{ 'value' => 3 }]])
     end
   end
 
   describe '#join' do
     before do
       2.times.map do |n|
-        subject.execute_async("SELECT #{n} AS value;")
+        subject.execute_async("SELECT #{n} AS value;", method: :exec_query)
       end
     end
 
     it 'joins the threads and give respective values, and clear workers' do
-      result = subject.join
+      result = convert_result_to_hash(subject.join)
 
       expected = 2.times.map do |n|
-        [{ 'value' => n.to_s }]
+        [{ 'value' => n }]
       end
 
-      expect(result.map(&:to_a)).to eq(expected)
+      expect(result).to eq(expected)
       expect(subject.workers).to be_empty
     end
   end
@@ -91,4 +92,13 @@ describe Gitlab::Database::ConnectionPool, lib: true do
       expect(subject).to be_closed
     end
   end
+
+  def convert_result_to_hash(values)
+    values.map do |result|
+      result.map do |row|
+        ActiveRecord::AttributeSet::Builder.new({})
+          .build_from_database(row, result.column_types).to_h
+      end
+    end
+  end
 end