BUG#12969301 : mysql_plugin: enable is ignored if plugin exists

This patch changes the mechanism by which the client enables a 
plugin. Instead of using INSERT IGNORE to reload a plugin library,
it now uses REPLACE INTO. This allows users to load a library
multiple times replacing the existing values in the mysql.plugin
table. This allows users to replace the symbol reference to a
different dl name in the table. Thus permitting enabling of 
multiple versions of the same library without first disabling
the old version.

A regression test was added to ensure this feature works.

1 files changed, 13 insertions, 1 deletions

diff --git a/mysql-test/r/mysql_plugin.result b/mysql-test/r/mysql_plugin.result
index 93567e28c3d..636b039047e 100644
--- a/mysql-test/r/mysql_plugin.result
+++ b/mysql-test/r/mysql_plugin.result
@@ -23,12 +23,24 @@ wacky	libdaemon_example.so
 wicky	libdaemon_example.so
 wonky	libdaemon_example.so
 #
+# Ensure the plugin is loaded.
+#
+SELECT * FROM mysql.plugin WHERE dl like '%libdaemon%' ORDER BY name;
+name	dl
+daemon_example	libdaemon_example.so
+#
+# Ensure the plugin is replaced.
+#
+SELECT * FROM mysql.plugin WHERE dl like '%libdaemon%' ORDER BY name;
+name	dl
+daemon_example	liblibdaemon_example.so
+#
 # Disable the plugin...
 #
 #
 # Ensure the plugin isn't loaded.
 #
-SELECT * FROM mysql.plugin WHERE dl like 'libdaemon%' ORDER BY name;
+SELECT * FROM mysql.plugin WHERE dl like '%libdaemon%' ORDER BY name;
 name	dl
 #
 # Attempt to load non-existant plugin