Oracle WITH 和 MATERIALIZE 提示充当函数的自治事务

Question

在 Oracle 12c 中，如果我在 WITH..AS 部分中使用 MATERIALIZE 提示的查询中调用一个函数，该函数调用就像一个自主事务：

DROP TABLE my_table;

CREATE TABLE my_table (
    my_column NUMBER
);

-- Returns number of records in table 
CREATE OR REPLACE FUNCTION my_function 
RETURN INTEGER
IS
    i INTEGER;
BEGIN
    SELECT COUNT(1) INTO i FROM my_table;
    RETURN i;
END;
/

-- Inserts one record to table 
INSERT INTO my_table (my_column) VALUES (9);

-- Returns number of records in table. This works correctly, returns 1
SELECT COUNT(1) AS "use simple select" FROM my_table;

-- Returns number of records in table. This works correctly, returns 1
WITH x AS (
    SELECT /*+ MATERIALIZE */ COUNT(1) AS "use WITH, MATERIALIZE" FROM my_table
)
SELECT * FROM x;

-- Returns number of records in table. This works correctly, returns 1
SELECT my_function AS "use FUNCTION" FROM dual;

-- Returns number of records in table. This works INCORRECTLY, returns 0. 
-- Function is called in autonomous transaction?
WITH x AS (
    SELECT /*+ MATERIALIZE */ my_function "use WITH,MATERIALIZE,FUNCTION" FROM dual
)
SELECT * FROM x;

ROLLBACK;

有人知道这是什么原因吗？它是 Oracle 错误还是旨在像这样工作？（为什么？）为什么只有WITH结合MATERIALIZED hint和FUNCTION call时才会这样？

Answer 1

这看起来像错误 15889476，"Wrong results with cursor-duration temp table and function running on an active transaction"；和 13253977 "Wrong results or error with cursor-duration temp table and PLSQL function running on an active transaction".

我可以在 11.2.0.3 上重现，但不能在 11.2.0.4 上重现；从 Husqvik 的评论来看，它似乎没有在 12.1.0.2 上重现。这与错误文档中受影响的版本和修复优先包含的信息一致。

有关详细信息，请参阅 MOS 文档 15889476.8 和 13253977.8。您可能需要联系 Oracle 支持以确认这是您遇到的问题，但它看起来非常相似。

Oracle WITH 和 MATERIALIZE 提示充当函数的自治事务

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