Bug #101389 getwarnings should check warning count before sending SHOW

• Submitted: 30 Oct 2020 0:30
• Modified: 30 Oct 2020 5:23
• Reporter: Trey Raymond
• Status: Verified
• Category: Connector / J
• Severity: S3 (Non-critical)
• Version: 8.0, 5.1
• OS: Any
• CPU Architecture: Any

[30 Oct 2020 0:30] Trey Raymond

Description:
refs
https://github.com/mysql/mysql-connector-j/blob/release/8.0/src/main/user-impl/java/com/my...

https://github.com/mysql/mysql-connector-j/blob/release/8.0/src/main/protocol-impl/java/co...

https://github.com/mysql/mysql-connector-j/blob/release/8.0/src/main/protocol-impl/java/co...

specifically this line
https://github.com/mysql/mysql-connector-j/blob/release/8.0/src/main/protocol-impl/java/co...

this function will send a 'show warnings' statement to the server even if the statement returned warningcount=0, which is quite expensive.  it should only send the SHOW query if count>0, else it already knows there are zero results.

How to repeat:
call getwarnings after any zero-warning statement, it will still run SHOW.
or use one of the popular libs like hibernate, jooq, etc which all suffer terribly from this.

Suggested fix:
wrap an if around that SHOW call.  easy fix!

[30 Oct 2020 5:23] MySQL Verification Team

Hello Trey Raymond,

Thank you for the report and feedback.

regards,
Umesh