| Bug #90420 | Contribution by Facebook: Query attributes | ||
|---|---|---|---|
| Submitted: | 13 Apr 2018 0:21 | Modified: | 18 Jan 2021 12:26 |
| Reporter: | FBContrib Admin | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: Connection Handling | Severity: | S4 (Feature request) |
| Version: | 8.0.11 | OS: | Any |
| Assigned to: | CPU Architecture: | Any | |
[13 Apr 2018 0:21]
FBContrib Admin
Query attributes (*) This code is contributed under the Facebook agreement
Contribution: fb_patch_43.txt (text/plain), 20.84 KiB.
[1 Oct 2018 22:27]
FBContrib Admin
Query attributes for 8.0.11 (*) This code is contributed under the Facebook agreement
Contribution: fb_patch_83.txt (text/plain), 22.16 KiB.
[18 Jan 2021 8:17]
Georgi Kodinov
Implemented as WL#12542 in 8.0.23
[18 Jan 2021 12:26]
Paul DuBois
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).
Description: Background innformation provided by Facebook: Abstract: This adds a way to tag COM_QUERY requests. Currently, queries sent over the network are encoded as follows: total packet length COM_QUERY query string The length of the query string is implicit from and calculated from the packet length. This change adds a new command called COM_QUERY_ATTRS with the following structure total packet length COM_QUERY_ATTRS total attributes length attributes string query string Note that query string length is still implicit. In order to avoid conflicting RPC values with Oracle, COM_QUERY_ATTRS was put at the end of the valid RPC range. Its value is set at 255. For upstream purposes, COM_QUERY_ATTRS and COM_QUERY can probably be merged, using capability flags to help with the format change. Repo: https://github.com/mysql/mysql-server Patch on top of 8.0.4: https://github.com/mysql/mysql-server/commit/577fbcf856cd693434d554545d499559bcdd3695 Facebook commits: https://github.com/facebook/mysql-5.6/commit/a619992 How to repeat: See description Suggested fix: See contribution code attached