MySQL Bugs: #92532: Contribution by Facebook: Performance schema for Query attributes

Bug #92532	Contribution by Facebook: Performance schema for Query attributes
Submitted:	21 Sep 2018 16:26	Modified:	18 Jan 2021 12:26
Reporter:	FBContrib Admin	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Performance Schema	Severity:	S3 (Non-critical)
Version:	8.0.11	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
Background innformation provided by Facebook:

This patch is a "Query attributes" contribution where COM_QUERY requests are tagged. It implements the session_query_attrs performance schema table in 8.0 to return information about attributes.

Repo: https://github.com/mysql/mysql-server
Patch on top of 8.0.11: https://github.com/mysql/mysql-server/commit/8.0

How to repeat:
See description

Suggested fix:
See contribution code attached

Performance schema for Query attributes 
(*) This code is contributed under the Facebook agreement

Contribution: fb_patch_82.txt (text/plain), 39.42 KiB.

Implemented measuring CPU usage for queries instrumented with query attributes (*) This code is contributed under the Facebook agreement

Contribution: fb_patch_84.txt (text/plain), 40.25 KiB.

Additional information related to the second part of the contribution (fb_patch_84.txt):

These patches contain the changes which affect the performance_schema table for query attributes too.

Implemented measuring CPU usage for queries instrumented with query attributes.
Added system table QUERY_PERF_COUNTER to output results of measurements.

Repo: https://github.com/mysql/mysql-server
Patch on top of 8.0.11: https://github.com/mysql/mysql-server/commit/8.0

Facebook commits:
- https://github.com/facebook/mysql-5.6/commit/5832232
- https://github.com/facebook/mysql-5.6/commit/453353b

Implemented as WL#12542 in 8.0.23

Posted by developer:
 
Fixed in 8.0.23.

For some applications, it may be useful to define metadata on a
per-query basis. Examples include the URL of the page that produced a
query, or extra processing information to be passed with a query for
use by a plugin such as an audit plugin or query rewrite plugin.
MySQL now supports this capability without the use of workarounds
such as specially formatted comments included in query strings:

* On the client side, the mysql_bind_param() C API function enables
  defining query attributes. These attributes apply to the next SQL
  statement sent to the server for execution. Additionally, the mysql and
  mysqltest clients have a query_attributes command that enables defining
  query attributes.

* On the server side, a component service provides access to query
  attributes. A component named query_attributes uses this service to
  implement a mysql_query_attribute_string() user-defined function (UDF)
  that enables obtaining attribute values within SQL statements. The
  query_attributes component is optional but must be installed for the UDF
  to be available.

Thanks to Facebook for suggesting the idea (and for contributing
code, although it was not used).