MySQL Bugs: #93202: connector/net doesn't need to run SHOW VARIABLES

Bug #93202	connector/net doesn't need to run SHOW VARIABLES
Submitted:	15 Nov 2018 7:06	Modified:	19 Jun 2019 16:50
Reporter:	Shane Bester (Platinum Quality Contributor)	Email Updates:
Status:	Closed	Impact on me:	None
Category:	Connector / NET	Severity:	S5 (Performance)
Version:	8.0.13	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
Same request as in:
 https://bugs.mysql.com/bug.php?id=93201

Please do not run SHOW VARIABLES.
Rather use SELECT @@varname;  alternative syntax.

How to repeat:
Look at how serverProps gets populated,  and how it is actually used.
Check method public virtual void Configure(MySqlConnection connection)
in C/NET Driver.cs.

It'll call LoadServerProperties at least once (depending on pool size/CacheServerProperties).

Yet, look when serverProps is referenced on the lines:

string licenseType = serverProps["license"];
MaxPacketSize = Convert.ToInt64(serverProps["max_allowed_packet"]);
serverProps.TryGetValue("character_set_client", out clientCharSet);
serverProps.TryGetValue("character_set_connection", out connCharSet);
string mode = Connection.driver.Property("sql_mode");
int caseSetting = Int32.Parse(connection.driver.Property("lower_case_table_names"));

Suggested fix:
Please optimize this code to avoid SHOW VARIABLES at any cost.
How about this instead:

SELECT @@max_allowed_packet, @@license, @@character_set_client, @@character_set_connection, @@lower_case_table_names, @@sql_mode;

Hello Shane,

Thank you for the report.
Observed this with VS 2017 and C/NET 8.0.13.

Regards,
Umesh

Posted by developer:
 
Fixed as of the upcoming MySQL Connector/NET  6.10.9 and 8.0.17 release, and here's the changelog entry:

Connector/NET connections executed SHOW VARIABLES unnecessarily.

Thank you for the bug report.