PostgreSQL plpgsql 存储过程、函数 - 状态、异常变量打印、异常捕获… - GET [STACKED] DIAGNOSTICS

背景

使用GET STACKED DIAGNOSTICS捕获异常时的STACK内容。

使用GET DIAGNOSTICS捕获运行过程中的状态值。

GET DIAGNOSTICS捕获运行过程中的状态值

There are several ways to determine the effect of a command. The first method is to use the GET DIAGNOSTICS command, which has the form:

GET [ CURRENT ] DIAGNOSTICS variable { = | := } item [ , ... ];  

GET DIAGNOSTICS integer_var = ROW_COUNT;  

Name	Type	Description
ROW_COUNT	bigint	the number of rows processed by the most recent SQL command
RESULT_OID	oid	the OID of the last row inserted by the most recent SQL command (only useful after an INSERT command into a table having OIDs)
PG_CONTEXT	text	line(s) of text describing the current call stack (see Section 43.6.8)

The GET DIAGNOSTICS command, previously described in Section 43.5.5, retrieves information about current execution state (whereas the GET STACKED DIAGNOSTICS command discussed above reports information about the execution state as of a previous error).

例子

CREATE OR REPLACE FUNCTION outer_func() RETURNS integer AS $$  
BEGIN  
  RETURN inner_func();  
END;  
$$ LANGUAGE plpgsql;  
  
CREATE OR REPLACE FUNCTION inner_func() RETURNS integer AS $$  
DECLARE  
  stack text;  
BEGIN  
  GET DIAGNOSTICS stack = PG_CONTEXT;  
  RAISE NOTICE E'--- Call Stack ---\n%', stack;  
  RETURN 1;  
END;  
$$ LANGUAGE plpgsql;  
  
SELECT outer_func();  
  
NOTICE:  --- Call Stack ---  
PL/pgSQL function inner_func() line 5 at GET DIAGNOSTICS  
PL/pgSQL function outer_func() line 3 at RETURN  
CONTEXT:  PL/pgSQL function outer_func() line 3 at RETURN  
 outer_func  
 ------------  
           1  
(1 row)  

GET STACKED DIAGNOSTICS捕获异常时的STACK内容

GET STACKED DIAGNOSTICS … PG_EXCEPTION_CONTEXT returns the same sort of stack trace, but describing the location at which an error was detected, rather than the current location.

Name	Type	Description
RETURNED_SQLSTATE	text	the SQLSTATE error code of the exception
COLUMN_NAME	text	the name of the column related to exception
CONSTRAINT_NAME	text	the name of the constraint related to exception
PG_DATATYPE_NAME	text	the name of the data type related to exception
MESSAGE_TEXT	text	the text of the exception’s primary message
TABLE_NAME	text	the name of the table related to exception
SCHEMA_NAME	text	the name of the schema related to exception
PG_EXCEPTION_DETAIL	text	the text of the exception’s detail message, if any
PG_EXCEPTION_HINT	text	the text of the exception’s hint message, if any
PG_EXCEPTION_CONTEXT	text	line(s) of text describing the call stack at the time of the exception (see Section 43.6.8)

例子

DECLARE  
  text_var1 text;  
  text_var2 text;  
  text_var3 text;  
BEGIN  
  -- some processing which might cause an exception  
  ...  
EXCEPTION WHEN OTHERS THEN  
  GET STACKED DIAGNOSTICS text_var1 = MESSAGE_TEXT,  
                          text_var2 = PG_EXCEPTION_DETAIL,  
                          text_var3 = PG_EXCEPTION_HINT;  
END;  

参考

https://www.postgresql.org/docs/11/static/plpgsql-control-structures.html#PLPGSQL-CALL-STACK

https://www.postgresql.org/docs/11/static/plpgsql-statements.html

《Using “GET DIAGNOSTICS integer_var = ROW_COUNT;” capture rows effect by the last SQL》

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