Manual:$wgDebugLogGroups

Details
Set to an array of log group keys to filenames.

If set,   output for that group will go to that file instead of the regular  .

Useful for enabling selective logging in production.

If a group is configured in  , then all debug messages with the according group key will be logged to that file, also if   is not set! With other words: If a group key is configured in  , messages will be written, even if an empty value of   generally disables debugging. }}

Log destinations may be one of the following:
 * false to completely remove from the output, including from $wgDebugLogFile.
 * string values specifying a filename or URI.
 * associative array with keys:
 * 'destination' desired filename or URI.
 * 'sample' an integer value, specifying a sampling factor (optional)
 * 'level' A \Psr\Log\LogLevel constant, indicating the minimum level log (optional, since 1.25)

Example
Example:

Advanced example:

This example logs debug messages of group "ConfirmEditExtension" to "debug-ext_confirmedit.log" and those of group "SpamRegex" to "debug-spam.log".