规格约束

自治事务执行时，将会在后台启动自治事务session，可以通过max_concurrent_autonomous_transactions设置自治事务执行的最大并行数量，该参数取值范围为0~10000，默认值为10。
当max_concurrent_autonomous_transactions参数设置为0时，自治事务将无法执行。
自治事务新启session后，将使用默认session参数，不共享主session下对象（包括session级别变量，本地临时变量，全局临时表的数据等）。
自治事务理论上限为10000，实际上限为动态值，参考GUC参数max_concurrent_autonomous_transactions描述。
自治事务受通信缓冲区影响，返回给客户端的信息大小受限于通信缓冲区长度，超过通信缓冲区长度时报错。

触发器函数不支持自治事务。

gaussdb=# CREATE TABLE test_trigger_des_tbl(id1 int, id2 int, id3 int);
CREATE TABLE

gaussdb=# CREATE OR REPLACE FUNCTION tri_insert_func() RETURNS TRIGGER AS
$$
DECLARE
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
INSERT INTO test_trigger_des_tbl VALUES(new.id1, new.id2, new.id3);
RETURN new;
END$$ LANGUAGE plpgsql;
ERROR:  Triggers do not support autonomous transactions
DETAIL:  N/A

gaussdb=# DROP TABLE test_trigger_des_tbl;
DROP TABLE

自治事务不支持非顶层匿名块调用（仅支持顶层自治事务，包括存储过程、函数和匿名块）。

gaussdb=# CREATE TABLE t1(a INT ,b TEXT);
CREATE TABLE

gaussdb=# DECLARE 
--PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
DECLARE 
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
DBE_OUTPUT.PRINT_LINE('JUST USE CALL.');
INSERT INTO t1 VALUES(1,'CAN YOU ROLLBACK!');
END;
INSERT INTO t1 VALUES(2,'I WILL ROLLBACK!');
ROLLBACK;
END;
/
JUST USE CALL.
ANONYMOUS BLOCK EXECUTE
gaussdb=# SELECT * FROM t1;
 a | b 
---+---
(0 rows)

gaussdb=# DROP TABLE t1;
DROP TABLE

自治事务仅支持PROCEDURE OUT参数传递ref cursor参数，不支持IN、INOUT以及FUNCTION传递ref cursor参数；仅支持在存储过程中使用自治事务OUT参数传递ref cursor参数，不支持在客户端（如gsql、jdbc）中直接调用。

--创建表
gaussdb=# CREATE TABLE sections(section_id INT);
CREATE TABLE
gaussdb=# INSERT INTO sections VALUES(1);
INSERT 0 1
gaussdb=# INSERT INTO sections VALUES(1);
INSERT 0 1
gaussdb=# INSERT INTO sections VALUES(1);
INSERT 0 1
gaussdb=# INSERT INTO sections VALUES(1);
INSERT 0 1

PROCEDURE OUT出参传递ref cursor（支持）

gaussdb=# CREATE OR REPLACE PROCEDURE proc_sys_ref(OUT c1 REFCURSOR)
IS
DECLARE
  PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
 OPEN c1 FOR SELECT section_id FROM sections ORDER BY section_id;

END;
/
CREATE PROCEDURE

gaussdb=# CREATE OR REPLACE PROCEDURE proc_sys_call() AS 
DECLARE
  c1 SYS_REFCURSOR;
  temp NUMBER(4);
BEGIN
  proc_sys_ref(c1);
  IF c1%ISOPEN THEN
    RAISE NOTICE '%','OK';
 END IF;

  LOOP
    FETCH c1 INTO temp;
    RAISE NOTICE '%',c1%ROWCOUNT;
    EXIT WHEN c1%NOTFOUND;
  END LOOP;
END;
/
CREATE PROCEDURE

gaussdb=# CALL proc_sys_call();
NOTICE:  OK
NOTICE:  1
NOTICE:  2
NOTICE:  3
NOTICE:  4
NOTICE:  4
 proc_sys_call 
---------------

(1 row)
gaussdb=# DROP PROCEDURE proc_sys_ref;
DROP PROCEDURE 
gaussdb=# DROP PROCEDURE proc_sys_call;
DROP PROCEDURE

PROCEDURE IN或INOUT出参传递REF CURSOR（不支持）

gaussdb=# CREATE OR REPLACE PROCEDURE proc_sys_ref(IN c1 REFCURSOR)
IS
DECLARE
  PRAGMA AUTONOMOUS_TRANSACTION;
  temp NUMBER(4);
BEGIN
  IF c1%ISOPEN THEN
    RAISE NOTICE '%','OK';
  END IF;

  LOOP
    FETCH c1 INTO temp;
    RAISE NOTICE '%',c1%ROWCOUNT;
    EXIT WHEN c1%NOTFOUND;
  END LOOP;
END;
/
CREATE PROCEDURE

gaussdb=# CREATE OR REPLACE PROCEDURE proc_sys_call() AS 
DECLARE
  c1 SYS_REFCURSOR;
  temp NUMBER(4);
BEGIN
  OPEN c1 FOR SELECT section_id FROM sections ORDER BY section_id;
  proc_sys_ref(c1);
END;
/
CREATE PROCEDURE

gaussdb=# CALL proc_sys_call();
ERROR:  Unsupported: ref_cursor parameter is not supported for autonomous transactions.
CONTEXT:  SQL statement "CALL proc_sys_ref(c1)"
PL/pgSQL function proc_sys_call() line 7 at PERFORM
gaussdb=# DROP PROCEDURE proc_sys_ref;
DROP PROCEDURE

FUNCTION RETURN传递ref cursor（不支持）

gaussdb=# DROP PROCEDURE IF EXISTS proc_sys_ref;
gaussdb=# CREATE OR REPLACE FUNCTION proc_sys_ref() RETURN SYS_REFCURSOR IS
DECLARE
  PRAGMA AUTONOMOUS_TRANSACTION;
        c1 SYS_REFCURSOR;
BEGIN
 OPEN c1 FOR SELECT section_id FROM sections ORDER BY section_id;
 return c1;
END;
/
ERROR:  Autonomous function do not support ref cursor as return types or out, inout arguments.
DETAIL:  N/A

FUNCTION OUT出参传递ref cursor（不支持）

gaussdb=# DROP FUNCTION IF EXISTS proc_sys_ref;
gaussdb=# CREATE OR REPLACE FUNCTION proc_sys_ref(C1 out SYS_REFCURSOR)
gaussdb-# return SYS_REFCURSOR
gaussdb-# IS
gaussdb$# declare
gaussdb$#   PRAGMA AUTONOMOUS_TRANSACTION;
gaussdb$# BEGIN
gaussdb$#  OPEN C1 FOR SELECT section_ID FROM sections ORDER BY section_ID;
gaussdb$#  return 1;
gaussdb$# END;
gaussdb$# /
ERROR:  Autonomous function do not support ref cursor as return types or out, inout arguments.
DETAIL:  N/A

客户端中（例如gsql，jdbc）直接调用带ref cursor出参的自治事务PROCEDURE（不支持，此时无法读取cursor数据）

gaussdb=# CREATE OR REPLACE PROCEDURE proc_sys_ref(OUT c1 REFCURSOR)
IS
DECLARE
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
OPEN c1 FOR SELECT section_id FROM sections ORDER BY section_id;
END;
/
CREATE PROCEDURE
gaussdb=# begin;
BEGIN
gaussdb=# call proc_sys_ref(null);
         c1
--------------------
 <unnamed portal 1>
(1 row)

gaussdb=# fetch "<unnamed portal 1>";
ERROR:  cursor "<unnamed portal 1>" does not exist
gaussdb=# end;
ROLLBACK
gaussdb=# DROP PROCEDURE proc_sys_ref;
DROP PROCEDURE
--删除表
gaussdb=# DROP TABLE sections;
DROP TABLE

自治事务函数不支持直接返回record类型或者out出参和record类型同时返回。

gaussdb=# CREATE TABLE test_in (id INT,a DATE);
CREATE TABLE

gaussdb=# CREATE OR REPLACE FUNCTION autonomous_out()
RETURNS RECORD
LANGUAGE PLPGSQL AS $$
DECLARE PRAGMA AUTONOMOUS_TRANSACTION;
         r1 RECORD;
BEGIN
    DBE_OUTPUT.PRINT_LINE('THIS IS IN AUTONOMOUS_F_139_7');
    TRUNCATE test_in;
    INSERT INTO test_in VALUES (1,'1909-01-01');
    SELECT * INTO r1 FROM test_in;
RETURN r1;
END;
$$;
CREATE FUNCTION

gaussdb=# SELECT ok.id,ok.a FROM autonomous_out() AS ok(id INT,a DATE);
ERROR:  unrecognized return type for PLSQL function.

gaussdb=# CREATE TYPE rec IS (e1 INTEGER, e2 VARCHAR2);
CREATE TYPE
gaussdb=# CREATE OR REPLACE FUNCTION func(ele3 INOUT VARCHAR2) RETURN rec AS
i INTEGER;
ele1 rec;
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
NULL;
RETURN ele1;
END;
/
CREATE FUNCTION

gaussdb=# CALL func(1);
 e1 | e2 
----+----
    | 
(1 row)

gaussdb=# DROP TABLE test_in;
DROP TABLE
gaussdb=# DROP FUNCTION autonomous_out;
DROP FUNCTION 
gaussdb=# DROP FUNCTION func;
DROP FUNCTION

不支持修改自治事务的隔离级别。

gaussdb=# CREATE OR REPLACE PROCEDURE auto_func(r INT)
AS
DECLARE
  a INT;
  PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
 a:=r;
END;
/
CREATE PROCEDURE
gaussdb=# call auto_func(1);
ERROR:  ERROR:  SET TRANSACTION ISOLATION LEVEL must be called before any query
CONTEXT:  SQL statement "SET TRANSACTION ISOLATION LEVEL SERIALIZABLE"
PL/pgSQL function auto_func(integer) line 6 at SQL statement
referenced column: auto_func
gaussdb=# DROP FUNCTION auto_func;
DROP FUNCTION

不支持自治事务返回集合类型（setof）。

gaussdb=# CREATE TABLE test_in (id INT,a DATE);
CREATE TABLE
gaussdb=# CREATE TABLE test_main (id INT,a DATE);
CREATE TABLE
gaussdb=# INSERT INTO test_main VALUES (1111,'2021-01-01'),(2222,'2021-02-02');
INSERT 0 2
gaussdb=# TRUNCATE test_in,test_main;
TRUNCATE TABLE
gaussdb=# CREATE OR REPLACE FUNCTION autonomous_f_022(num1  INT) RETURNS SETOF test_in
LANGUAGE PLPGSQL AS $$
DECLARE
count INT :=3;
test_row test_in%ROWTYPE;
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
    WHILE TRUE
    LOOP
    IF count=3 THEN
    NULL;
    ELSE 
    IF count=2 THEN
        INSERT INTO test_main VALUES (count,'2021-03-03');
        GOTO pos1;
    END IF;                
    END IF;
    count=count-1;
    END LOOP;
    INSERT INTO test_main VALUES (1000,'2021-04-04');
     <<pos1>>
     FOR test_row IN SELECT * FROM test_main
     LOOP
        RETURN NEXT test_row;
       END LOOP;
      RETURN;
END;
$$;
ERROR:  Autonomous transactions do not support RETURN SETOF.
DETAIL:  N/A

gaussdb=# DROP TABLE test_main;
DROP TABLE
gaussdb=# DROP TABLE test_in;
DROP TABLE

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