| Bug #103059 | system_variable_source does not report DYNAMIC when queried from sys_var update | ||
|---|---|---|---|
| Submitted: | 22 Mar 2021 12:35 | Modified: | 22 Mar 2021 13:23 |
| Reporter: | Yura Sorokin (OCA) | Email Updates: | |
| Status: | Verified | Impact on me: | |
| Category: | MySQL Server: InnoDB storage engine | Severity: | S3 (Non-critical) |
| Version: | 8.0.23 | OS: | Any |
| Assigned to: | CPU Architecture: | Any | |
| Tags: | Contribution | ||
[22 Mar 2021 13:12]
Yura Sorokin
8.0 patch
Attachment: bug_103059.diff (application/octet-stream, text), 625 bytes.
[22 Mar 2021 13:23]
MySQL Verification Team
Hello Yura Sorokin, Thank you for the report and contribution. Please ensure to re-send the patch "Contribution" tab. Otherwise we would not be able to accept it. regards, Umesh
[22 Mar 2021 22:56]
Yura Sorokin
8.0 patch (*) I confirm the code being submitted is offered under the terms of the OCA, and that I am authorized to contribute it.
Contribution: bug_103059.diff (application/octet-stream, text), 625 bytes.
Description: Several existing InnoDB system variables (including innodb_undo_tablespaces, innodb_buffer_pool_size, innodb_log_file_size) use the following pattern in their "update" handler to determine the source from where the var is being changed. Internally they use something like ****************************************** acquire_sysvar_source_service(); if (sysvar_source_svc != nullptr) { static const char *variable_name = "<var_name>"; enum enum_variable_source source; if (!sysvar_source_svc->get( variable_name, static_cast<unsigned int>(strlen(variable_name)), &source)) { if (source != COMPILED) { ... } } } release_sysvar_source_service(); ****************************************** However, this approach does not work because according to ****************************************** int set_var::update(THD *thd) { int ret = 0; /* for persist only syntax do not update the value */ if (type != OPT_PERSIST_ONLY) { if (value) ret = (int)var->update(thd, this); else ret = (int)var->set_default(thd, this); } /* For PERSIST_ONLY syntax we dont change the value of the variable for the current session, thus we should not change variables source/timestamp/user/host. */ if (ret == 0 && type != OPT_PERSIST_ONLY) { update_source_user_host_timestamp(thd); } return ret; } ****************************************** the "source" of the "sys_var" change is set to DYNAMIC only AFTER "update()" handler is called (inside "update_source_user_host_timestamp()"). Therefore, when system_variable_source component is queried from within the sys_var update handler, user get the source of previous operation rather than the current one being executed. How to repeat: Changing innodb_undo_tablespaces for the first time won't produce a deprecation warning in the error log. Suggested fix: Set variable source to DYNAMIC before calling the "update()" handler var->set_source(enum_variable_source::DYNAMIC);