From 5cb4ea7fc4f1c15c049dff717e8d4d5dfdc4b279 Mon Sep 17 00:00:00 2001
From: Daniel Westendorf <daniel@prowestech.com>
Date: Tue, 8 Oct 2024 23:22:55 -0600
Subject: [PATCH] Add support for force `CREATE FUNCTION` (#146)

* Switch from `CREATE FUNCTION` to `CREATE OR REPLACE FUNCTION`

In a rails app, with existing Clickhouse schema w/a function defined, a `rails db:schema:load` will not always succeed; this is because the function may already exist.

```
Code: 609. DB::Exception: User-defined function 'uuid7ToDateTime' already exists. (FUNCTION_ALREADY_EXISTS) (version 23.9.6.20 (official build))
```
---
 lib/active_record/connection_adapters/clickhouse_adapter.rb  | 4 ++--
 lib/clickhouse-activerecord/schema_dumper.rb                 | 2 +-
 spec/cluster/migration_spec.rb                               | 5 ++++-
 .../migrations/dsl_create_function/1_create_some_function.rb | 1 +
 spec/single/migration_spec.rb                                | 5 ++++-
 5 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/lib/active_record/connection_adapters/clickhouse_adapter.rb b/lib/active_record/connection_adapters/clickhouse_adapter.rb
index 8d7257e2..2b31c3bf 100644
--- a/lib/active_record/connection_adapters/clickhouse_adapter.rb
+++ b/lib/active_record/connection_adapters/clickhouse_adapter.rb
@@ -356,8 +356,8 @@ def create_table(table_name, **options, &block)
         end
       end
 
-      def create_function(name, body)
-        fd = "CREATE FUNCTION #{apply_cluster(quote_table_name(name))} AS #{body}"
+      def create_function(name, body, **options)
+        fd = "CREATE#{' OR REPLACE' if options[:force]} FUNCTION #{apply_cluster(quote_table_name(name))} AS #{body}"
         do_execute(fd, format: nil)
       end
 
diff --git a/lib/clickhouse-activerecord/schema_dumper.rb b/lib/clickhouse-activerecord/schema_dumper.rb
index 44a2bd8c..61fe71c1 100644
--- a/lib/clickhouse-activerecord/schema_dumper.rb
+++ b/lib/clickhouse-activerecord/schema_dumper.rb
@@ -112,7 +112,7 @@ def function(function, stream)
       stream.puts "  # FUNCTION: #{function}"
       sql = @connection.show_create_function(function)
       stream.puts "  # SQL: #{sql}" if sql
-      stream.puts "  create_function \"#{function}\", \"#{sql.gsub(/^CREATE FUNCTION (.*?) AS/, '').strip}\"" if sql
+      stream.puts "  create_function \"#{function}\", \"#{sql.gsub(/^CREATE FUNCTION (.*?) AS/, '').strip}\", force: true" if sql
     end
 
     def format_options(options)
diff --git a/spec/cluster/migration_spec.rb b/spec/cluster/migration_spec.rb
index eb60f93a..09edf193 100644
--- a/spec/cluster/migration_spec.rb
+++ b/spec/cluster/migration_spec.rb
@@ -70,9 +70,12 @@
           let(:directory) { 'dsl_create_function' }
 
           it 'creates a function' do
+            ActiveRecord::Base.connection.do_execute('CREATE FUNCTION forced_fun AS (x, k, b) -> k*x + b', format: nil)
+
             subject
 
-            expect(ActiveRecord::Base.connection.functions).to match_array(['some_fun'])
+            expect(ActiveRecord::Base.connection.functions).to match_array(['some_fun', 'forced_fun'])
+            expect(ActiveRecord::Base.connection.show_create_function('forced_fun').chomp).to eq('CREATE FUNCTION forced_fun AS (x, y) -> (x + y)')
           end
         end
       end
diff --git a/spec/fixtures/migrations/dsl_create_function/1_create_some_function.rb b/spec/fixtures/migrations/dsl_create_function/1_create_some_function.rb
index f49bd4df..940a1ee6 100644
--- a/spec/fixtures/migrations/dsl_create_function/1_create_some_function.rb
+++ b/spec/fixtures/migrations/dsl_create_function/1_create_some_function.rb
@@ -3,5 +3,6 @@
 class CreateSomeFunction < ActiveRecord::Migration[7.1]
   def up
     create_function :some_fun, "(x,y) -> x + y"
+    create_function :forced_fun, "(x,y) -> x + y", force: true
   end
 end
diff --git a/spec/single/migration_spec.rb b/spec/single/migration_spec.rb
index c82fb32c..7f6565c3 100644
--- a/spec/single/migration_spec.rb
+++ b/spec/single/migration_spec.rb
@@ -369,9 +369,12 @@
       context 'dsl' do
         let(:directory) { 'dsl_create_function' }
         it 'creates a function' do
+          ActiveRecord::Base.connection.do_execute('CREATE FUNCTION forced_fun AS (x, k, b) -> k*x + b', format: nil)
+
           subject
 
-          expect(ActiveRecord::Base.connection.functions).to match_array(['some_fun'])
+          expect(ActiveRecord::Base.connection.functions).to match_array(['some_fun', 'forced_fun'])
+          expect(ActiveRecord::Base.connection.show_create_function('forced_fun').chomp).to eq('CREATE FUNCTION forced_fun AS (x, y) -> (x + y)')
         end
       end
     end