Oracle Database 11g Release 2. Please also tag oracle for search purposes.

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28
votes
13answers
76k views

Eliminate duplicates in ListAgg (Oracle)

Prior to Oracle 11.2 I was using a custom aggregate function to concatenate a column into a row. 11.2 Added the LISTAGG function, so I am trying to use that instead. My problem is that I need to ...
26
votes
3answers
42k views

What is the difference between sys and system accounts in Oracle databases?

There are two ways to connect to Oracle as a administrator using sqlplus: sqlplus sys as sysdba sqlplus system/manager These accounts should be uses for different purposes, I suppose. Which tasks ...
25
votes
4answers
12k views

Why is OS authentication considered poor security for Oracle databases?

Oracle is deprecating OS authentication according to the Oracle Database Security Guide, which says Be aware that the REMOTE_OS_AUTHENT parameter was deprecated in Oracle Database 11g Release ...
21
votes
8answers
20k views

How do you version your Oracle database changes?

I am interested to know what methods other people are using to keep track of changes made to the database including table definition changes, new objects, packages changes, etc. Do you use flat files ...
14
votes
3answers
11k views

How to differentiate between SQL and PL/SQL?

I know the question might sound too stupid, but I never understood this part. SQL*Plus works with both SQL and PL/SQL. How do I know whether some code is SQL or PL/SQL? If my code has a for ...
14
votes
4answers
5k views

What is the significance of a semicolon at the end of SQL*Plus commands?

Some statements like create table, insert into etc take a semicolon at the end: CREATE TABLE employees_demo ( employee_id NUMBER(6) , first_name VARCHAR2(20) , last_name ...
14
votes
3answers
1k views

Oracle is not using a unique index for a long key

I have a table with 250K rows in my test database. (There are a few hundred millions in production, we can observe the same issue there.) The table has an nvarchar2(50) string identifier, not null, ...
12
votes
1answer
2k views

Commit vs Fast Commit vs Commit Cleanout in Oracle Database

I was wondering whether someone could verify my understanding regarding the differences between those 3 terms as pertaining to Oracle Databases. Many sources confuse these terms and do not explain ...
11
votes
2answers
3k views

Security for Application Developers doing PL/SQL work in Oracle

How do you handle the lack of Schema level privileges in Oracle? Oracle’s security architecture works well for applications that only need object level privileges and it works well for DBAs that need ...
9
votes
3answers
3k views

How can I ensure that only one copy of a procedure is running in Oracle?

We have the need to ensure that only one copy of a particular procedure is running in Oracle. If it is already running and a user tries to open another, then it should error. Whats the best method ...
9
votes
2answers
2k views

Oracle Shutdown Method

Shutting down a database before doing an upgrade or a patch can be done several ways. shutdown immediate; or shutdown abort; startup restrict; shutdown immediate; or shutdown abort; startup ...
9
votes
2answers
1k views

LNNVL Justification

LNNVL is an oracle built in function that returns TRUE for conditions evaluating to FALSE or UNKNOWN, and returns FALSE for conditions evaluating to TRUE. My question is what would be the benefit of ...
9
votes
2answers
843 views

Why is a “non-single-group group function” allowed in a subselect but not on it's own?

Why does the first query not fail with the same error as the second: with w as (select 1 product_id, 10 units from dual union all select 2, 5 from dual) select sum(units) from (select product_id, ...
9
votes
4answers
34k views

Execute a script with SQLPlus containing blanks, semi-colons, and forward slashes

Occasionally I will get a script that will run fine in SQL Developer or Toad, but requires modification in order to be run successfully from SQL*Plus. Here is a worst case example containing multiple ...
8
votes
3answers
6k views

I have a powerful machine with 70 GB RAM. How many Oracle instances with 20 GB can be created?

I have powerful machine with 70 GB RAM. I created one Oracle instance with 20 GB as sga_target. I am not able to create another Oracle instance with sga_target > 10G even when I keep the ...
8
votes
1answer
44k views

Getting “ORA-00942: table or view does not exist” while table does exist

I'm fairly new to Oracle database. I have installed Oracle Database 11g R2 on Oracle Linux 6. I have successfully created a new database with dbca and connected to the database using: $ sqlplus "/ as ...
8
votes
2answers
3k views

Limit redo for materialized view complete refresh or manual equivalent

A materialized view(MV) log can be used to allow a MV to do a fast refresh which only modifies the data that has changed. However, various conditions prevent the MV from using the log and therefore ...
8
votes
2answers
12k views

Why in Oracle 11gR2 I can't drop the materialized view with the same user that created it?

I created a materialized view with the DI_TEST_AL user, let's name it MY_MVIEW. It appears in the USER_OBJECTS table as MATERIALIZED VIEW, I try to drop it, I get a success message, but the object is ...
8
votes
1answer
606 views

How can a datapump export have its resource usage limited on linux?

Doing an export of a number of users causes high CPU and I/O usage. I can mitigate the effects of the CPU usage using Resource Manager and setting the export session to a low priority group, but how ...
7
votes
4answers
797 views

Can this business logic be enforced by a conditional database constraint?

I am trying to duplicate the business logic embodied an intranet C# web application in the database so that other databases can access it and work under the same rules. This "rule" seems difficult to ...
7
votes
2answers
44k views

“ORA-01950: no privileges on tablespace 'SYSTEM' ” : What error is it?

Earlier I created a user : SQL>create user suhail identified by password SQL>User created. SQL>Grant create session,create table to suhail; SQL>Grant Succeeded. but when I login as ...
7
votes
2answers
1k views

are there significant differences with 500+ million row tables in Oracle?

I am in a database designer in a data warehouse environment. I am used to dealing with tables with a maximum of 1 millions rows and am now faced with tables with more than half a billion rows. Are ...
7
votes
1answer
33k views

Importing schema to new or different tablespace

Is there a convenient way to import a schema into Oracle 11gR2 using a single new or different tablespace than where the data originated? As an example, I have exported BLOG_DATA from OLDDB, where ...
7
votes
1answer
164 views

Cardinality is so far off from reality

I've got a table where the cardinality for plans just seems waaaaaay too high - despite updating stats and even trying dynamic sampling for Oracle 11gR2. select count(*) from table1 where col1 = ...
7
votes
1answer
916 views

Can I use Oracle Standard or Enterprise edition for my own training purposes?

Question is about Oracle licensing terms. I would like to learn more about Oracle Database administration. Unfortunatelly I am using 32 bit verison of LInux, so I can't install Oracle 11 XE (I can't ...
7
votes
1answer
25k views

How to free up disk space? which logs/directories to clean?

I want to free up the disk space on my Linux machine. I've drill down the space usage and found that the following directories have a big size /u01/app/11.2.0/grid/cv/log ...
7
votes
1answer
2k views

Generate XML using Oracle XML schema

I have some XML schema definitions that have been registered using DBMS_XMLSCHEMA. I have created tables using the XMLTypes generated. I can create XML using XMLQuery and if I understand correctly, ...
6
votes
4answers
1k views

Does an IOT guarantee order in a select?

We need to add a priority column to a table that gets hit about 250 times a second, approx 170 selects, 125 inserts and 60 updates. The column will be a simple number(1). The priority does not matter ...
6
votes
4answers
1k views

How do I sync instance A to instance B without losing any of the data already on instance B?

Like I said in a comment below, I'm no DBA and I'm still in a learning process. Here's my scenario : I have an Oracle server running a couple schemas (let' call it Source). What I would like to do ...
6
votes
2answers
37k views

How do you get the explain plan?

Can some one please explain a bit about explain plan, and how does one get the explain plan for a query. Also, if there is any sql script which can be used as utility for this, that would be great.
6
votes
1answer
3k views

Comments in EXPDB parameter file

Is there a way to put comments in a data pump export parameter file?
6
votes
3answers
10k views

Trouble killing sessions then immediately dropping users in Oracle 11g XE

I would like to be able to kill active sessions by a given user, and then drop that user, and do so within a single database call. Here is what I have so far: DECLARE cursor c is select * ...
6
votes
2answers
758 views

Oracle Advanced Queuing LIFO

With Oracle's Advanced Queuing is there a way to dequeue messages in a LIFO (last in first out) order? There is an indication through a lack of information that this is not an option, but perhaps ...
6
votes
2answers
1k views

Identify which parameters were passed to a procedure (Oracle)

Procedures in PL/SQL can have default values for parameters, but the caller can pass values that are identical to the default values. Is there a way from within the PL/SQL to determine whether a ...
6
votes
2answers
11k views

Learning to Optimize SQL Queries and Understand Execution Plans - Resources?

I find myself writing more and more SQL queries at work (mostly Oracle 11g, but some SQL Server 2005-2008) and have started creating some pretty complex views for the rest of the analyst team. They ...
6
votes
1answer
95 views

Why are some aggregates treated differently in the RHS of a rule in the model clause?

With my limited understanding of the model clause, I'd expected the following three queries to return the same results because there are no nulls in the data, and the functions are equivalent: select ...
6
votes
1answer
9k views

Cannot change service name for Oracle

I'm trying to change the service name of an Oracle 11.2.0.3 installation on a Windows 2003 server. During installation the service name was defined with the default domain, but we'd like to get rid ...
6
votes
1answer
2k views

DBMS_Resource_Manager.Calibrate_IO Usage

DBMS_Resource_Manager has a procedure called Calibrate_IO with a Physical Disks input parameter. The documentation says this value should be set to the... Approximate number of physical disks in ...
6
votes
3answers
5k views

Add Oracle Label Security to an existing Oracle installation

We are using Amazon EC2 to host some Oracle database instances while we are evaluating and prototyping some software. We are using the AMIs provided by Oracle - specifically, Oracle Database 11g ...
6
votes
1answer
452 views

Sudden increase in log_file_sync waits

I'm on Oracle 11gR2 with a 2 node RAC system. It's shared fiber storage to an EMC Clariion. Last friday things went bad..fast. All of the sudden processes that normally ran fine for years became ...
6
votes
1answer
1k views

Global locking for multi-master Oracle GoldenGate replication

This is a very complex scenario, but I figured a state-of-the-art challenge might interest some of the many high-end users of dba.se. Problem I'm working on an intercontinental data replication ...
6
votes
1answer
965 views

Package state not re-intialized on raise_application_error

When a package has state and the header is changed, the first call gets an error stack something like this: ORA-04068: existing state of packages has been discarded ORA-04061: existing state of ...
5
votes
2answers
2k views

What storage engines work with Oracle?

http://en.wikipedia.org/wiki/Database_engine mentions about database engines aka storage engines. What all storage engines can be used with the Oracle database?
5
votes
4answers
11k views

Why does = NULL not work in Oracle?

I recently realized that we need to use a special syntax IS NULL to compare a literal to NULL. Why does = NULL not work here?
5
votes
2answers
745 views

Defining constraints in `CREATE TABLE` statements

Recently I have been using a Database Abstraction Layer built by a Python web-framework called web2py (click for their DAL syntax). They include the option to include your constraints within the ...
5
votes
2answers
2k views

Updating rows conditionally with a gapless ascending value

A user has a table they would like to update. Depending on the data in other columns they want a particular column to be updated with an ascending value starting from 1 that is gap-less. The rows ...
5
votes
2answers
4k views

What is the difference between ROLE and PRIVILEGE for Oracle?

Is role a collection of certain privileges?
5
votes
2answers
2k views

What is the difference between these two create table statements?

a) SQL> CREATE TABLE xml_tab1(poDoc XMLTYPE); Table created. SQL> desc xml_tab1; Name Null? Type ----------------------------------------- -------- ...
5
votes
1answer
245 views

Why does the CBO not chose a lower cost skip scan without stats?

In the script below, the CBO chooses an INDEX FAST FULL SCAN over an INDEX SKIP SCAN (this is illustrated by the queries with the UNION ALL but you can demonstrate it is true with just explain plan ...
5
votes
1answer
8k views

How to find the schema name of a data pump dmp file?

I have been given a DMP data pump export file to import into my local Oracle instance. I've tried running this command line: impdp full=Y directory=DATA_PUMP_DIR dumpfile=MyDumpFile.dmp ...