ORA-28405
This post is an update to an earlier one, which I have now deleted. I tested the first part of it in an Oracle 11.1.0.6 database. First I created a role which was identified by a password: SQL> conn...
View ArticleClustering_Factor
I attended the UKOUG conference early in December. While I was there, I went to a presentation by Chris Saxon, where he explained how Oracle decides when to use an index. The example below, which I ran...
View ArticleClustering_Factor = 0
I looked at clustering_factor in the previous post and wondered what might cause it to be well below the number of blocks in the table. Chris Saxon suggested it might be due to rows with null values. I...
View ArticleINSERT /*+ APPEND */ Hint Does Not Seem to Work Consistently
I ran the following SQL in an Oracle 11.2.0.1 database:SQL> create table tab1 2 (col1 number) 3 / Table created. SQL> alter session set sql_trace = true 2 / Session altered. SQL> insert...
View ArticleClik here to view.
SELECTs Do Not Block UPDATEs
I went on my first DBA course in 1997 and the lecturer there explained that readers do not block writers in an Oracle database. I had an issue recently which appeared to contradict this so I have...
View ArticleCreating Tables in the UNDO Tablespace??
I was reading an article written by Martin Widlake in Oracle Scene Issue 58 (Autumn/Winter 2015). It said:The second new item is the UNDO tablespace. This is a special tablespace that is only used for...
View ArticleRMAN Backup Without Compression
I wanted to test the effect of RMAN backup compression on an Oracle 11.2.0.1 database running on Windows. I configured the flash recovery area, closed the database and mounted it. Then I did a backup...
View ArticleRMAN Backup With Compression
I repeated the test from the previous post but this time I tried to compress the backup. At this stage I need your help. I believe I have used the free compression which does not require an extra...
View ArticleBind Variables
This example, tested on Oracle 11, shows how you can define bind variables in SQL*Plus, assign values to them in PL/SQL then display those values afterwards back in SQL*Plus:SQL> variable bv1...
View Article%TYPE Declaration Gives PLS-00302
A developer reported a problem with a %TYPE declaration which was returning PLS-00302 in an Oracle 10 database. The cause turned out to be a variation on a problem which I have already reported....
View ArticleHow to See When an Oracle Role Was Created
You can get the date and time a role was created from the CTIME column in SYS.USER$. You can see what I mean in the example below, which I tested in an Oracle 11.2.0.4 database. First I created a role...
View ArticleORA-01109
I read that you cannot take a tablespace offline if the database is only mounted so I decided to test this in an Oracle 11.2.0.4 database. I mounted the database and tried to take the USERS tablespace...
View ArticleARCHIVE_LAG_TARGET on Oracle 11.2.0.4
I read about this parameter, which is supposed to force a redo log switch after a certain number of seconds. I decided to try it out in an Oracle 11.2.0.4 database. This is the record from the alert...
View ArticleORA-39710 and ORA-00704
I tried to use dbua to upgrade a database from Oracle 11.2.0.4 to Oracle 12.1.0.2. Part way through, my PC lost connection with the UNIX server hosting the database. I tried to connect to the database...
View ArticleMaking a Hot Backup and Doing an Incomplete Recovery
This post shows how to do a hot backup followed by an incomplete recovery. I ran it on an Oracle 11.2.0.4 test database. First I checked that the database was in ARCHIVELOG mode:SQL> select log_mode...
View ArticleSUBSTR Versus LIKE in Oracle 11.2
I was reading an old SQL tuning book which was printed in 2002. It said that a where clause with like could often use an index whereas a similar clause using substr could not. I wondered if this might...
View ArticleHow to Automatically Trace a User's Sessions
This post shows how you can use a logon trigger to automatically trace all sessions for a given user. This can be useful where an application is launched from a desktop but fails before the DBA has had...
View ArticleDeferred Segment Creation not Supported for Partitioned Tables in Oracle...
I tried to create a partitioned table with deferred segment creation in an Oracle 11.2.0.1 database.First I tried to do so explicitly but this did not work:SQL> create table partitioned_table 2...
View ArticleDatapump Does not Export Permissions on Objects Owned by SYS
This post was sponsored by Technimove I was reminded recently that Datapump does not export permissions on objects owned by SYS so I decided to write a post about it for my blog. It was tested on an...
View ArticleClik here to view.
SELECT ANY SEQUENCE
I used to think that a user with SELECT ANY TABLE and SELECT ANY DICTIONARY could see anything in a database. I found out today that these 2 privileges do not allow you to SELECT from another user’s...
View Article