| Tables created with NOLOGGING [message #54965] |
Fri, 20 December 2002 10:46  |
jack
Messages: 123
Registered: September 2000
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Senior Member |
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Our database is in Archive Log Mode. If I create a table specifying NOLOGGING will any log entries be made when the tables is created? Also will any logging occur on insert, update, and deletes for this table?
Example:
CREATE TABLE EAST_EMP NOLOGGING AS
SELECT * FROM EMP WHERE LOC = 'E';
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| Re: Tables created with NOLOGGING [message #54998 is a reply to message #54965] |
Mon, 23 December 2002 13:42  |
Trifon Anguelov
Messages: 514
Registered: June 2002
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Senior Member |
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When you issue CREATE TABLE ... you will be changing the data dictionary tables, and since all the dictionary changes are always logged the answer to your first question is YES - CREATE TABLE.. will generate redo logs. That's because when you create a table, Oracle issues update and insert statements to the dictionary which go into the redo logfiles. So during recovery,Oracle encounters these statements and succeeds in creating the table.
when you use UNRECOVERABLE and NOLOGGING in Oracle8 you will only avoid the redolog entries generation for certain operation that can be easily recovered without using the database recovery mechanism. In this case the actual DDL statements will sent to the redo logs the information needed to modify the data dictionary but all rows loaded into the table during the "create as select" statement are not sent to the redo logs.
For the INSERT, UPDATE, DELETE with NOLOGGING clause enabled, you can read This and This . That will help you understand how NOLOGGING clause works.
Hope that helps,
clio_usa
OCP - DBA
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