更新时间:2024-06-03 GMT+08:00

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,取值范围:0~10000,默认值: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);
    NOTICE:  The 'DISTRIBUTE BY' clause is not specified. Using 'id1' as the distribution column by default.
    HINT:  Please use 'DISTRIBUTE BY' clause to specify suitable data distribution column.
    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、匿名块)。
    gaussdb=# CREATE TABLE t1(a INT ,b TEXT);
    NOTICE:  The 'DISTRIBUTE BY' clause is not specified. Using 'a' as the distribution column by default.
    HINT:  Please use 'DISTRIBUTE BY' clause to specify suitable data distribution column.
    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);
    NOTICE:  The 'DISTRIBUTE BY' clause is not specified. Using 'section_id' as the distribution column by default.
    HINT:  Please use 'DISTRIBUTE BY' clause to specify suitable data distribution column.
    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
    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)
    2. 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
    3. 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
    4. FUNCTION OUT出参传递ref cursor(不支持)
      gaussdb=# CREATE OR REPLACE FUNCTION proc_sys_ref(c1 OUT SYS_REFCURSOR)
      RETURN SYS_REFCURSOR
      IS
      DECLARE
        PRAGMA AUTONOMOUS_TRANSACTION;
      BEGIN
       OPEN c1 FOR SELECT section_id FROM sections ORDER BY section_id;
       RETURN 1;
      END;
      /
      ERROR:  Autonomous function do not support ref cursor as return types or out, inout arguments.
      DETAIL:  N/A
    5. 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
  • 分布式自治事务不支持下推(IMMUTABLE、STABLE类型)。
    gaussdb=# CREATE OR REPLACE PROCEDURE autonomous_test_in_p_116(num1 INT ) 
    IMMUTABLE 
    AS
    DECLARE
    PRAGMA AUTONOMOUS_TRANSACTION;
    BEGIN
    PERFORM pg_sleep(1);
    END;
    /
    ERROR:  Autonomous transactions do not support STABLE/IMMUTABLE.
    DETAIL:  Please remove stable/immutable.
    
    gaussdb=# CREATE OR REPLACE PROCEDURE autonomous_test_in_p_117(num1 INT ) STABLE AS
    DECLARE
    PRAGMA AUTONOMOUS_TRANSACTION;
    BEGIN
    PERFORM pg_sleep(1);
    END;
    /
    ERROR:  Autonomous transactions do not support STABLE/IMMUTABLE.
    DETAIL:  Please remove stable/immutable.
  • 分布式不支持检测。
    gaussdb=# CREATE TABLE test_lock (id INT,a DATE);
    NOTICE:  The 'DISTRIBUTE BY' clause is not specified. Using 'id' as the distribution column by default.
    HINT:  Please use 'DISTRIBUTE BY' clause to specify suitable data distribution column.
    CREATE TABLE
    gaussdb=# INSERT INTO test_lock VALUES (10,SYSDATE),(11,SYSDATE),(12,SYSDATE);
    INSERT 0 3
    gaussdb=# CREATE OR REPLACE FUNCTION autonomous_test_lock(num1 INT,num2 INT) RETURNS
    INTEGER LANGUAGE plpgsql AS $$
    DECLARE num3 INT := 4;
    PRAGMA AUTONOMOUS_TRANSACTION;
    BEGIN
    UPDATE test_lock SET a=SYSDATE WHERE id =11;
    RETURN num1+num2+num3;
    END;
    $$;
    CREATE FUNCTION
    
    gaussdb=# START TRANSACTION;
    START TRANSACTION
    gaussdb=# UPDATE test_lock SET a=SYSDATE WHERE id =11;
    UPDATE 1
    gaussdb=# CALL autonomous_test_lock(1,1);
    ERROR:  ERROR:  Lock wait timeout: thread 139874535470848 on node datanode1 waiting for ShareLock on transaction 16214 after 120000.124 ms
    DETAIL:  blocked by hold lock thread 139874577413888, statement <UPDATE test_lock SET a = "sysdate"() WHERE id =11;>, hold lockmode ExclusiveLock.
    CONTEXT:  SQL statement "UPDATE test_lock SET a=SYSDATE WHERE id =11"
    PL/SQL function autonomous_test_lock(integer,integer) line 5 at SQL statement
    referenced column: autonomous_test_lock
    
    gaussdb=# END;
    ROLLBACK
    gaussdb=# DROP TABLE test_lock;
    DROP TABLE
  • 自治事务函数不支持直接返回record类型和out出参、record类型同时返回。
    gaussdb=# CREATE OR REPLACE FUNCTION auto_func() RETURN RECORD
    AS
    DECLARE
      TYPE rec_type IS RECORD(c1 INT, c2 INT);
      r rec_type;
      PRAGMA AUTONOMOUS_TRANSACTION;
    BEGIN
      r.c1:=101;
      r.c2:=201;
      RETURN r;
    END;
    /
    CREATE FUNCTION
    
    gaussdb=# SELECT auto_func();
    ERROR:  unrecognized return type for PLSQL function.
    CONTEXT:  referenced column: auto_func
  • 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 FUNCTION
    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/SQL function auto_func(integer) line 6 at SQL statement
    referenced column: auto_func
  • 不支持自治事务返回集合类型(setof)。
    gaussdb=# CREATE OR REPLACE FUNCTION test_set() RETURN SETOF INT
    AS
    DECLARE
    PRAGMA AUTONOMOUS_TRANSACTION;
    BEGIN
        RETURN QUERY (SELECT unnest(ARRAY[ARRAY[1, 2], ARRAY[3, 4]]));
    END;
    /
    ERROR:  Autonomous transactions do not support RETURN SETOF.
    DETAIL:  N/A