From 02621f2a14d1348baa7262452ce6b8e938d5fd78 Mon Sep 17 00:00:00 2001
From: Gary Pendergast <gary@pento.net>
Date: Fri, 8 May 2015 12:22:25 +0000
Subject: [PATCH] Upgrades: If a table has already been converted to `utf8mb4`,
 there's no need to try and convert it again.

Props gabrielperezs for the initial patch.

See #32310.


Built from https://develop.svn.wordpress.org/trunk@32456


git-svn-id: http://core.svn.wordpress.org/trunk@32426 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-admin/includes/upgrade.php | 11 +++++++++++
 wp-includes/version.php       |  2 +-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/wp-admin/includes/upgrade.php b/wp-admin/includes/upgrade.php
index a8b4c740a5..dde618ab02 100644
--- a/wp-admin/includes/upgrade.php
+++ b/wp-admin/includes/upgrade.php
@@ -1751,6 +1751,17 @@ function maybe_convert_table_to_utf8mb4( $table ) {
 		}
 	}
 
+	$table_details = $wpdb->get_row( "SHOW TABLE STATUS LIKE '$table'" );
+	if ( ! $table_details ) {
+		return false;
+	}
+
+	list( $table_charset ) = explode( '_', $table_details->Collation );
+	$table_charset = strtolower( $table_charset );
+	if ( 'utf8mb4' === $table_charset ) {
+		return true;
+	}
+
 	return $wpdb->query( "ALTER TABLE $table CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci" );
 }
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index d5fa32dad4..c35b6c709a 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.3-alpha-32455';
+$wp_version = '4.3-alpha-32456';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.