MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
The MySQL server and most MySQL clients are compiled with the DBUG package originally created by Fred Fish. When you have configured MySQL for debugging, this package makes it possible to get a trace file of what the program is doing. SeeSection 5.9.1.2, “Creating Trace Files”.
This section summarizes the argument values that you can specify in debug options on the command line for MySQL programs that have been built with debugging support.
The DBUG package can be used by invoking a program with the--debug[=ordebug_options]-# [option. If you specify thedebug_options]--debugor-#option without adebug_optionsvalue, most MySQL programs use a default value. The server default isd:t:i:o,/tmp/mysqld.traceon Unix andd:t:i:O,\mysqld.trace在Windows上。th的影响is default is:
d: Enable output for all debug macrost: Trace function calls and exitsi: Add PID to output lineso,/tmp/mysqld.trace,O,\mysqld.trace: Set the debug output file.
Most client programs use a defaultdebug_optionsvalue ofd:t:o,/tmp/, regardless of platform.program_name.trace
Here are some example debug control strings as they might be specified on a shell command line:
--debug=d:t --debug=d:f,main,subr1:F:L:t,20 --debug=d,input,output,files:n --debug=d:t:i:O,\\mysqld.traceFormysqld,也有可能改变DBUG设置在runtime by setting thedebugsystem variable. This variable has global and session values:
mysql> SET GLOBAL debug = 'debug_options'; mysql> SET SESSION debug = 'debug_options';Changing the globaldebugvalue requires privileges sufficient to set global system variables. Changing the sessiondebugvalue requires privileges sufficient to set restricted session system variables. SeeSection 5.1.9.1, “System Variable Privileges”.
Thedebug_optionsvalue is a sequence of colon-separated fields:
field_1:field_2:...:field_NEach field within the value consists of a mandatory flag character, optionally preceded by a+or-character, and optionally followed by a comma-separated list of modifiers:
[+|-]flag[,modifier,modifier,...,modifier]The following table describes the permitted flag characters. Unrecognized flag characters are silently ignored.
Flag |
Description |
|---|---|
|
Enable output from DBUG_ 在MySQL中,常见的调试宏关键词,使基于“增大化现实”技术e |
|
Delay after each debugger output line. The argument is the delay, in tenths of seconds, subject to machine capabilities. For example, |
|
Limit debugging, tracing, and profiling to the list of named functions. An empty list enables all functions. The appropriate |
|
Identify the source file name for each line of debug or trace output. |
|
Identify the process with the PID or thread ID for each line of debug or trace output. |
|
Identify the source file line number for each line of debug or trace output. |
|
Print the current function nesting depth for each line of debug or trace output. |
|
Number each line of debug output. |
|
Redirect the debugger output stream to the specified file. The default output is |
|
Like |
|
Limit debugger actions to specified processes. A process must be identified with the |
|
Print the current process name for each line of debug or trace output. |
|
When pushing a new state, do not inherit the previous state's function nesting level. Useful when the output is to start at the left margin. |
|
Do function |
|
Enable function call/exit trace lines. May be followed by a list (containing only one modifier) giving a numeric maximum trace level, beyond which no output occurs for either debugging or tracing macros. The default is a compile time option. |
The leading+or-character and trailing list of modifiers are used for flag characters such asdorfthat can enable a debug operation for all applicable modifiers or just some of them:
With no leading
+or-, the flag value is set to exactly the modifier list as given.With a leading
+or-, the modifiers in the list are added to or subtracted from the current modifier list.
The following examples show how this works for thedflag. An emptydlist enabled output for all debug macros. A nonempty list enables output only for the macro keywords in the list.
These statements set thedvalue to the modifier list as given:
mysql> SET debug = 'd'; mysql> SELECT @@debug; +---------+ | @@debug | +---------+ | d | +---------+ mysql> SET debug = 'd,error,warning'; mysql> SELECT @@debug; +-----------------+ | @@debug | +-----------------+ | d,error,warning | +-----------------+A leading+or-adds to or subtracts from the currentdvalue:
mysql> SET debug = '+d,loop'; mysql> SELECT @@debug; +----------------------+ | @@debug | +----------------------+ | d,error,warning,loop | +----------------------+ mysql> SET debug = '-d,error,loop'; mysql> SELECT @@debug; +-----------+ | @@debug | +-----------+ | d,warning | +-----------+Adding to“all macros enabled”results in no change:
mysql> SET debug = 'd'; mysql> SELECT @@debug; +---------+ | @@debug | +---------+ | d | +---------+ mysql> SET debug = '+d,loop'; mysql> SELECT @@debug; +---------+ | @@debug | +---------+ | d | +---------+Disabling all enabled macros disables thedflag entirely:
mysql> SET debug = 'd,error,loop'; mysql> SELECT @@debug; +--------------+ | @@debug | +--------------+ | d,error,loop | +--------------+ mysql> SET debug = '-d,error,loop'; mysql> SELECT @@debug; +---------+ | @@debug | +---------+ | | +---------+