Mutating Table in Oracle 11 caused by a function

Question

We\'ve recently upgraded from Oracle 10 to Oracle 11.2. After upgrading, I started seeing a mutating table error caused by a function rather than a trigger (which I\'ve nev

Answer 1

Statement-Level Read Consistency and Transaction-Level Read Consistency".

From the manual:

"If a SELECT list contains a function, then the database applies statement-level read consistency at the statement level for SQL run within the PL/SQL function code, rather than at the parent SQL level. For example, a function could access a table whose data is changed and committed by another user. For each execution of the SELECT in the function, a new read consistent snapshot is established".

Both concepts are explained in the "Oracle® Database Concepts" :

http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/consist.htm#sthref1955

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->>> UPDATE

->>>*Section added after the OP was closed

The rule

The technical rule , well linked by Mr Kemp(@jeffrey-kemp) and well explained by Toon Koppelaars here, is reported in "Pl/Sql language reference - Controlling Side Effects of PL/SQL Subprograms"(your function violates RNDS reads no database state):

When invoked from an INSERT, UPDATE, or DELETE statement, the function cannot query or modify any database tables modified by that statement.

If a function either queries or modifies a table, and a DML statement on that table invokes the function, then ORA-04091 (mutating-table error) occurs.

PL/SQL Functions that SQL Statements Can Invoke