The second and terminal release of Oracle Corporations Oracle 11g database product. 11.2 was released for Linux on September 1st, 2009. New features added include RAC One Node, Improved data compression ratios (up to 20x), Edition Based Redefinition, Recursive Subquery Factoring, Instance Caging, ...

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2answers
4k views

Why can't we specify group functions in Oracle in the where clause?

SQL> desc tab1 Name Null? Type ----------------------------------------- -------- ---------------------------- ID ...
4
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2answers
2k views

Determine Index Compression Candidates Online

By doing the following I can determine if an index will benefit from compression and how many columns should be included in the compression: ANALYZE INDEX Owner.IndexName VALIDATE STRUCTURE OFFLINE; ...
7
votes
2answers
2k 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 ...
6
votes
3answers
3k 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 ...
8
votes
2answers
603 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 ...
5
votes
1answer
1k views

DROP PARTITION strategy using LIST-REF composite partitioning

We have a large Oracle 11gR2 instance with some tables that have recently become an annoyance when deleting data. This database powers a large optimization cluster that takes input metadata from the ...
3
votes
1answer
1k views

Unable to create a tablespace, unusual error

I'm having difficulty creating tablespaces with Oracle 11gR2 on a fiber attached disk array. Permissions are correct and there is ample space available. I can create tablespaces on other mounts that ...
2
votes
1answer
494 views

Recover Oracle database after drive loss Interview Question

How would you answer this as an interview question? The database crashed and you lost a drive containing one of your control files and another drive containing an entire redo log group. You ...
3
votes
2answers
284 views

How to create a user with a particular user_id?

Is it possible to specify the user_id of a user while creating it? SQL> create user user1 identified by user1; User created. SQL> select user_id, username from all_users where ...
3
votes
1answer
619 views

Oracle query against SQL Server database giving inconsistent results

We have multiple Oracle 11.2.0.2 databases with og4odbc database links to a SQL Server 2008 database. A particular table in the SQL Server database has two Varchar(36) columns. The following ...
1
vote
1answer
196 views

Why am I not seeing any benefits of parallel execution when parallel clause is used?

I have these two methods of creating a table and populating with rows. The first one uses a parallel (degree 3) clause, so I expected the inserts to be much faster. But I timed the time taken for a) ...
5
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 ...
3
votes
1answer
2k views

Optimal value for LOG_BUFFER parameter

The wait event “log buffer space” according to the documentation can indicate that the log buffer is too small or the I/O is slow. We have a system seeing this event in which the redo buffer ...
4
votes
2answers
1k 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 ...
2
votes
2answers
9k views

SGA_MAX_SIZE and SGA_TARGET

We recently increased sga_max_size to 4g from 2g but didnt increase sga_target, is it ok not to increase sga_target?? reason we wanted to increase sga is to reduce wait time on sequential reads in our ...
2
votes
2answers
2k views

What does 'nls' in nls_date_format stand for?

For example: alter session set nls_date_format = 'DD-MON-YYYY hh24:mi:ss'; changes the date format for the session. What is nls here?
5
votes
2answers
508 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 ...
4
votes
1answer
417 views

Help with Query Tuning

EDIT - drachenstern: see this question for more information on this problem and on the source of his query below: Group data by non-unique keys by distinct time range Can someone please advise ...
2
votes
2answers
3k views

In Oracle, how to globally enable parallel execution?

In Oracle 11g, is there a way to tell the database to use parallel execution whenever possible by setting a flag etc, rather than using PARALLEL hints with every SQL statement?
1
vote
1answer
8k views

Where all can the /*+ PARALLEL */ hint be used?

It works with SELECT and UPDATE statements. Are there some more statements with which it works? I was able to use it with create, but am not sure if the hint was actually considered. SQL> create ...
8
votes
3answers
5k 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 ...
3
votes
2answers
3k views

What is the difference between ROLE and PRIVILEGE for Oracle?

Is role a collection of certain privileges?
4
votes
1answer
801 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 ----------------------------------------- -------- ...
4
votes
3answers
998 views

Detect Index Coalesce

Is there a way to know if a COALESCE has been done on an index? Doing one doesn't seem to update the CREATED, LAST_DDL_TIME, or LAST_ANALYZED attributes. Note: I am not referring to the COALESCE ...
4
votes
2answers
785 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 ...
17
votes
10answers
32k 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 ...
5
votes
1answer
619 views

Case Behavior Changed Between 11.2.0.1 and 11.2.0.2

I have a case open with Oracle and they say they can't reproduce this. Running the following in 11.2.0.1 or lower produces two rows from both of these queries, but in 11.2.0.2 the second query ...
2
votes
3answers
326 views

How does a database use the SYS schema even when we change the password?

From the thread What is the difference between sys and system accounts in Oracle databases?, I understand that sys schema is supposed to be used only by the database. But still an administrator can ...
13
votes
4answers
2k 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 ...
23
votes
3answers
23k 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 ...
5
votes
3answers
884 views

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

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 ...
8
votes
1answer
420 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 ...
10
votes
2answers
2k 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 ...
22
votes
4answers
8k 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 ...
16
votes
8answers
10k 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 ...
1
vote
1answer
720 views

Can a Wallet be used with SQL Developer? How?

I have a Wallet configured and working fine for SQLPlus. Is there a way to make it work with SQL Developer?
3
votes
1answer
378 views

Is there a way to allow a proxy connection to use passed authentication in a public database link?

I think the answer to this is no, but I could be wrong. If nothing else it might be nice for others to be aware of this limitation of proxy connections.