From 3895435f5f147188c9f6972039e972cd9e960357 Mon Sep 17 00:00:00 2001
From: Matias Grunberg <matias@yellowspot.dev>
Date: Mon, 19 Apr 2021 17:49:30 -0300
Subject: [PATCH 1/2] add create index if exists support

See
https://github.com/rails/rails/commit/7ba08037f8d807cce2a25b0445743d07adfbe44c
---
 .../sqlserver/schema_creation.rb                   | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/lib/active_record/connection_adapters/sqlserver/schema_creation.rb b/lib/active_record/connection_adapters/sqlserver/schema_creation.rb
index 44b96602b..0b70b8d50 100644
--- a/lib/active_record/connection_adapters/sqlserver/schema_creation.rb
+++ b/lib/active_record/connection_adapters/sqlserver/schema_creation.rb
@@ -33,6 +33,20 @@ def visit_TableDefinition(o)
           sql
         end
 
+        def visit_CreateIndexDefinition(o)
+          if_not_exists = o.if_not_exists
+
+          o.if_not_exists = false
+
+          sql = super
+
+          if if_not_exists
+            sql = "IF NOT EXISTS (SELECT name FROM sysindexes WHERE name = '#{o.index.name}') #{sql}"
+          end
+
+          sql
+        end
+
         def add_column_options!(sql, options)
           sql << " DEFAULT #{quote_default_expression(options[:default], options[:column])}" if options_include_default?(options)
           if options[:null] == false

From bc48cd93449cbe6642e85c5d7c51790023524323 Mon Sep 17 00:00:00 2001
From: Matias Grunberg <matias@yellowspot.dev>
Date: Mon, 19 Apr 2021 17:51:00 -0300
Subject: [PATCH 2/2] add changelog item

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 38bc6660b..27d6a66e6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@
 - [#885](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/885) Fix the quoting of ActiveModel attributes
 - [#890](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/890) Fix removal of invalid ordering from select statements
 - [#881](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/881) Dump column collation to schema.rb and allow collation changes using column_change
+- [#891](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/891) Add support for if_not_exists to indexes
 
 #### Changed