•URN: file://component_log_sink_json 

•Multiple uses permitted: Yes. 

•Output destination: This sink determines its output destination based on the default error log destination, which is given by the log_error  system variable: 

•If log_error  names a file, the sink bases output file naming on that file name, plus a numbered . NN .json  suffix, with NN  starting at 00. For example, if log_error  is file_name , successive instances of log_sink_json  named in the log_error_services  value write to file_name .00.json , file_name .01.json , and so forth. 

•If log_error  is stderr , the sink writes to the console. If log_sink_json  is named multiple times in the log_error_services  value, they all write to the console, which is likely not useful. 

•Performance Schema support: Writes to the error_log  table. Provides a parser for reading error log files created by previous server instances. 

## The log_sink_syseventlog Component 

•Purpose: Implements error logging to the system log. This is the Event Log on Windows, and syslog  on Unix and Unix-like systems. See Section 5.4.2.8, “Error Logging to the System Log” . 

•URN: file://component_log_sink_syseventlog 

•Multiple uses permitted: No. 

•Output destination: Writes to the system log. Does not use the default error log destination. 

•Performance Schema support: Does not write to the error_log  table. Does not provide a parser for reading error log files created by previous server instances. 

## The log_sink_test Component 

•Purpose: Intended for internal use in writing test cases, not for production use. 

•URN: file://component_log_sink_test 

Sink properties such as whether multiple uses are permitted and the output destination are not specified for log_sink_test  because, as mentioned, it is for internal use. As such, its behavior is subject to change at any time. 

## 5.5.4 Query Attribute Components 

As of MySQL 8.0.23, a a component service provides access to query attributes (see Section 9.6, “Query Attributes” ). The query_attributes  component uses this service to provide access to query attributes within SQL statements. 

•Purpose: Implements the mysql_query_attribute_string()  function that takes an attribute name argument and returns the attribute value as a string, or NULL  if the attribute does not exist. 

•URN: file://component_query_attributes 

Developers who wish to incorporate the same query-attribute component service used by query_attributes  should consult the mysql_query_attributes.h  file in a MySQL source distribution. 

## 5.6 MySQL Server Plugins 

