From 52994c6e3edda6b82c3773317294a6898592ef79 Mon Sep 17 00:00:00 2001
From: Ryuta Kamizono <kamipo@gmail.com>
Date: Tue, 26 Jan 2021 18:58:13 +0900
Subject: [PATCH] Set charset name utf8mb4 by default

mysql2 gem dropped testing for MySQL 5.1 which was released in Dec 2008
and already EOL in Dec 2013 at efa47a935447bb96f178c11ce32834f877c36b77.

If we no longer support MySQL 5.1, utf8 (utf8mb3) is not appropriate
default encoding for MySQL 5.5 or higher, utf8mb4 should be set for
that.

FYI, Rails 6.0 no longer support MySQL 5.1 and set utf8mb4 by default.

https://github.com/rails/rails/pull/33608
https://github.com/rails/rails/pull/33853
---
 README.md            | 4 ++--
 lib/mysql2/client.rb | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 72ff37ff0..5e26875d2 100644
--- a/README.md
+++ b/README.md
@@ -233,7 +233,7 @@ Mysql2::Client.new(
   :database,
   :socket = '/path/to/mysql.sock',
   :flags = REMEMBER_OPTIONS | LONG_PASSWORD | LONG_FLAG | TRANSACTIONS | PROTOCOL_41 | SECURE_CONNECTION | MULTI_STATEMENTS,
-  :encoding = 'utf8',
+  :encoding = 'utf8mb4',
   :read_timeout = seconds,
   :write_timeout = seconds,
   :connect_timeout = seconds,
@@ -309,7 +309,7 @@ Use the value `mysql2` as the adapter name. For example:
 ``` yaml
 development:
   adapter: mysql2
-  encoding: utf8
+  encoding: utf8mb4
   database: my_db_name
   username: root
   password: my_password
diff --git a/lib/mysql2/client.rb b/lib/mysql2/client.rb
index 607ad6d6a..31e9e3301 100644
--- a/lib/mysql2/client.rb
+++ b/lib/mysql2/client.rb
@@ -43,8 +43,8 @@ def initialize(opts = {})
         end
       end
 
-      # force the encoding to utf8
-      self.charset_name = opts[:encoding] || 'utf8'
+      # force the encoding to utf8mb4
+      self.charset_name = opts[:encoding] || 'utf8mb4'
 
       ssl_options = opts.values_at(:sslkey, :sslcert, :sslca, :sslcapath, :sslcipher)
       ssl_set(*ssl_options) if ssl_options.any? || opts.key?(:sslverify)