Avoid Mutating Error In
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Fix mutating error in trigger in oracle Oracle mutating trigger table errors Oracle tips by Burleson A mutation table is defined as a table that is mutating trigger in oracle 10g with example changing. But in dealing with triggers, it is a table that has the possibility of changing. What this means to a trigger is that if the trigger reads a table, it canMutating Trigger In Oracle 11g
not change the table that it read from. This does not impact the exclusive use of :OLD and :NEW. It says that if the trigger reads the table (such as using a SELECT query), that changes (even using :NEW) will fail. This can also happen when a trigger on a parent table causes an insert on a child table referencing a foreign key. Mutating mutating trigger with example Tables Each new release of the Oracle database reduces the impact of the mutating table error on triggers and they are much less of a problem with Oracle9i and above. If a trigger does result in a mutating table error, the only real option is to rewrite the trigger as a statement-level trigger. Mutating table errors only impact row level triggers. But to use a statement level trigger, some data may need to be preserved from each row, to be used by the statement level trigger. This data can be stored in a PL/SQL collection or in a temporary table. A simple row level trigger that causes a mutating table error can result in a very complicated statement level trigger to achieve the needed result. Here are some important items to remember about triggers. On insert triggers have no :OLD values. On delete triggers have no :NEW values. Triggers do not commit transactions. If a transaction is rolled back, the data changed by the trigger is also rolled back. Commits, rollbacks and save points are not allowed in the trigger body. A commit/rollback affects the entire transaction, it is all
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answer site for database professionals who wish to improve their database skills and learn from others in the community. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask http://www.dba-oracle.com/t_avoiding_mutating_table_error.htm a question Anybody can answer The best answers are voted up and rise to the top What are the causes and solutions for mutating table errors? up vote 7 down vote favorite 1 I understand mutating table errors are caused by a design flaw or problematic query. An old query was recently put into production which throws a mutating table error. Our DBA solved the problem but we do http://dba.stackexchange.com/questions/5432/what-are-the-causes-and-solutions-for-mutating-table-errors not know how. What exactly causes mutating table errors and how would our DBA have fixed the problem? sql oracle trigger plsql share|improve this question edited Jun 25 '15 at 17:56 Mahi_0707 1033 asked Sep 6 '11 at 8:46 parmanand 107238 add a comment| 3 Answers 3 active oldest votes up vote 13 down vote accepted The most likely cause of a mutating table error is the misuse of triggers. Here is a typical example: you insert a row in table A a trigger on table A (for each row) executes a query on table A, for example to compute a summary column Oracle throws an ORA-04091: table A is mutating, trigger/function may not see it This is an expected and normal behaviour, Oracle wants to protect you from yourself since Oracle guarantees: (i) that each statement is atomic (i.e will either fail or succeed completely) (ii) that each statement sees a consistent view of the data Most likely when you write this kind of trigger you would expect the query (2) to see the row inserted on (1). This would be in contradiction with both points above since the update is not finished yet (there could be more rows to be inserted). Oracle could return
Editions: US United States Australia United Kingdom Japan Newsletters Forums Resource Library Tech Pro Free Trial Membership Membership My Profile People Subscriptions My http://www.techrepublic.com/article/learn-to-avoid-the-mutating-table-problem-in-oracle/ stuff Preferences Send a message Log Out TechRepublic Search GO Topics: CXO http://www.geekinterview.com/question_details/38947 Cloud Big Data Security Innovation Software Data Centers Networking Startups Tech & Work All Topics Sections: Photos Videos All Writers Newsletters Forums Resource Library Tech Pro Free Trial Editions: US United States Australia United Kingdom Japan Membership Membership My Profile People Subscriptions My stuff Preferences Send in oracle a message Log Out Data Management Learn to avoid the mutating table problem in Oracle Mutating tables in Oracle can drive any IT database manager insane when it comes to tracking down the culprit. With a clear idea of the table design required, however, this problem can be avoided. By Scott Robinson | April 14, 2003, 12:00 AM mutating error in PST RSS Comments Facebook Linkedin Twitter More Email Print Reddit Delicious Digg Pinterest Stumbleupon Google Plus Tables are everything to IT database managers in ERP database environments. The organization of database tables, their relationships, and the manner in which they are managed are a fair indicator of the overall quality of performance you can expect from the system.So when something can happen to mess up your tables, you want to watch out for it. In Oracle, there’s a nasty snare out there waiting for you. It's Oracle error ORA-04091, the mutating table error, and the best way to deal with it is to avoid it altogether. This article will explain why.When tables mutateThere are several causes of mutating tables, but in general a table mutation error will result if you create a trigger on a table that attempts to examine the current table. Also, the error is given when an attempt is made to examine a parent table in a cascading update/delete.Why are these considered errors? It’s obvious when you think about i
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Was this answer useful?Yes 1 Reply manikandan Dec 8th, 2006 if the trigger attempts to select or modify the table while the trigger has not completed (ie. table is in transition). then mutating trigger error occurs.because the table is in middle of a transaction so it causes the trigger to mutate.you can change the trigger to statement level and apply the logic there. Was this answer useful?Yes Reply vikramssheth ProfileAnswers by vikramssheth Jan 30th, 2007 We can override this problem using temporary Table Concept. Was this answer useful?Yes Reply sripri ProfileAnswers by sripriQuestions by sripri May 8th, 2007 Mutating trigger has similar concept to that of deadlock. When a table is in the half way of executing a transaction and is the owner of a trigger and if the same table is accessed by the trigge