Oracle is a RDBMS (Relational Database Management System) created by Oracle Corporation. It supports a large number of languages and application development frameworks. Its primary languages are SQL, PL/SQL and Java. Also included is support for C (Pro*C, OCI and EXTPROC), C++ (OCCI) and Java (JDBC) ...

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For Oracle, we mount the instance to the database or mount the database to the instance?

The following text is extract from oracle documentation. Start the instance, and mount and open the database. This can be done in unrestricted mode, allowing access to all users, or in ...
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Why do we need to backup Oracle archive logs along with datafiles

Oracle® Database Backup and Recovery Basics 10g Release 2 (10.2) says that Archived redo logs are the key to successful media recovery. Back them up regularly. But, I wonder, why backups of ...
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3k views

how to use dual foreign key in oracle 10g

I have created two tables create table ref1(id varchar2(3) primary key); create table ref2(id varchar2(3) primary key); Now I want to create a third table with a single column as foreign key for ...
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How to get a list of locked accounts / check that account is locked?

I can use following statement to unlock an account: ALTER USER username ACCOUNT UNLOCK But which statement can I use to verify that account is currently locked out?
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What is Key Preserved Table concept?

I read in the Oracle Documentation about key-preserved table in Updating Join Views Section. However, I didn't find any simple to way understand it. I hope to receive some simple conceptual details ...
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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 ...
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1answer
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Why I don't need to COMMIT in database trigger?

We can't COMMIT/ROLLBACK in DML triggers because transaction is handled manually after DML statement. However, database triggers seems to be an exception. For example, suppose there's a database ...
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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.
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What are the top 5 design decisions which need to be made when implementing a database?

I am implementing an Oracle System to store event alerts from an application so I guess all the schema, database design will be handled by the application through a sript. I am new to Database ...
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Building Dynamic Oracle Where Clause

I'm working on application that uses dynamic query to do a select statement based on user input, after discussing security with DBAs they want me to convert my dynamic select statement into Stored ...
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175 views

Replicating only changes made by a specific database user

I am performing parallel testing. We have upgraded the legacy batch jobs to a new framework which we need to test against the existing batch jobs. In the existing setup, I have web application which ...
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3answers
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What does NVL stand for?

What does NVL stand for? I'm talking about the Oracle and Informix (perhaps some others too) function used to filter out non NULL values from query results (similar to COALESCE in other databases).
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What's the best way to list groups of values that are contained in other groups

For example, starting with a table like this: create table t as select 'A' as x, level as y from dual connect by level<=5 union all select 'B' as x, level+2 as y from dual connect by level<=5 ...
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Simplified/automated datafile free disk space reclaim

On Oracle version 11g: After Googling, I can't find a simple way to reclaim free space after deleting a table. I've found a lot of explanations, telling how the datafile becomes fragmented, the big ...
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3answers
922 views

Alternative for OPTIMIZER_FEATURES_ENABLE

I've installed a PHP driven application in a client's 9i server (Oracle9i Release 9.2.0.1.0 - 64bit Production). Certain queries are having an awful performance (it can use from 15 minutes to hours ...
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3answers
831 views

Database replication and consistency check

I got a question about 2 databases (oracle 10g) that I have, let's call them A and B. A have some information(in various tables) and I want B to get a partial copy of some tables from A, and ...
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Oracle Enterprise Manager 11g dbconsole “Internet Explorer cannot display the webpage”

The dbconsole is configured and started, but when I navigate to it, Internet Explorer shows the page stating that "Internet Explorer cannot display the webpage". This is the error that means that IE ...
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1answer
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Export table without BLOB column

I have a big table with BLOB objects and some references from other tables to this one. I prepare dev and test schema for my app by making expdp (data pump) from production, then anonymizing data on ...
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3answers
8k 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 * ...
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1answer
572 views

If an 'after' DDL trigger causes an error, is the DDL rolled back?

It has been suggested that DDL is logically performed something like this: begin COMMIT; perform any appropriate pre-DDL trigger code; do the ddl; perform any appropriate post-DDL ...
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Oracle clean up

I have an Oracle database on a VMWare image that seems to be slowly eating all my available disk space. I would like to know if there is a command or script that would perform some kind of clean up of ...
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3answers
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What could be the reason for disallowing a sub query in the values clause?

For example SQL> create table dates(d date); Table created. SQL> insert into dates select sysdate from dual; 1 row created. SQL> select * from dates; D --------- 28-MAY-11 SQL> ...
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“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 ...
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optimizing a compare query

Suppose I have two tables, A and B, and I know that size(A) = size(B). I want to confirm that the data in both tables is the same in three given columns, suppose they are X, Y, and Z (there are no ...
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Grant create permission on a specific schema in Oracle 11g

I have two users A and B. I want to grant B the permission to create, drop, etc. all tables in A's schema. As far as I can see, I can grant B full access to all schemas not a specific one. Is this ...
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1answer
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How will Oracle fill a datafile added to a tablespace?

I have a tablespace with one datafile which is 50% used. If I add a new datafile to the tablespace - will the first datafile continue to be used until it reaches full capacity and only then will ...
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How to connect to a remote Oracle server from Windows machine using PL/SQL Developer?

I understand that I need to configure database address in the TNSNAMES.ORA file but where should I put this file? UPDATE I defined the $TNS_ADMIN variable, created the TNSNAMES.ORA file, added new ...
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How do I allow users to see grants, view definitions, PL/SQL, etc in a database without granting them access to change those objects

As a developer, I need to be able to access the design of the database/database objects from production so I can ensure I'm working with the latest and greatest version of the objects I'm developing ...
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1answer
199 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 ...
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3answers
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Bulk database update/insert from CSV file

I am implementing application specific data import feature from one database to another. I have a CSV file containing say 10000 rows. These rows need to be inserted/updated into database. There ...
5
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1answer
3k views

Is there a way to export an Oracle database to a CREATE DATABASE command?

I have an existing Oracle 11 instance, I want to export the database (which was created via DBCA) to an equivalent "CREATE DATABASE" command, handling the character set, etc. I'd also like to get a ...
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Cardinality rule for bitmap indexes

The Oracle documentation includes the following advice: A bitmap index should be built on each of the foreign key columns of the fact table or tables In that reference, there is even a bitmap ...
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sqlnet.ora or tnsnames.ora changes require reboot?

Anytime you change Oracle's sqlnet.ora or tnsnames.ora files, does the system require a reboot? In my instance, I only have the Oracle client installed on the machine I'm referring to, but out of ...
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1answer
160 views

Retrieve Indices of Associative Array as Collection

In PL/SQL, suppose I have some associative array defined as follows: declare type a_arr_t is table of PLS_INTEGER index by PLS_INTEGER; a_arr a_arr_t; I then, sparsely, populate the ...
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2answers
3k views

Session in “Sql*net message from client”, but is active

I've Googled around, and my impression is that Sql*net message from client suggests the Oracle DBMS is waiting for the client to send new commands to the DBMS, and therefore any time spent in ...
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2answers
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Restricting database access per IP addresses

I have filtered IP addresses to an access DB server like this: Set the sqlnet.ora tcp.validnode_checking = YES tcp.invited_nodes = (localhost, 192.168.100.130, 192.168.100.186) But in my ...
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Oracle - Automate Export/Unload of Data

Oracle SQL Developer has an option to export the contents of a query result to various formats (CSV/fixed width/Excel/XML). Is there any way to automate it? If not, what free tools are available ...
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660 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 ...
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Oracle partition by interval using persian calendar

Oracle supports Persian (Jalali) calendar in DDL queries, I can easily say: select to_char(register_date, 'YYYY-MM-DD', 'nls_calendar=persian') from my_table; I created a table as: create ...
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1answer
271 views

Oracle: DB *partial* constraint?

I am pretty new to Oracle and the database world. I am not sure if the title makes any sense at all, so I'll just go ahead and explain my situation. I currently have a table at hand that records ...
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2answers
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Product of n Rows

From this data (assuming the number of rows is not known in advance): with q1 as (select mod(ora_hash(level),5) c1 from dual connect by level <=4) select * from q1; /* C1 -- 2 1 4 1 */ I ...
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ORA-04031: unable to allocate bytes of shared memory (“”,“”,“”,“”)

I am receiving this error in a development database. It happens on some specific queries (simple inserts and deletes via .NET application). The database is used by one user, and error happens ...
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1answer
940 views

Are there performance benefits to turning off archivelogging? Is it wise?

The first part of the question is pretty simple; has anyone run a DB in both archivelog and noarchivelog mode? Were there any measurable performance benefits to turning off logging that you could ...
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1answer
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Oracle RAC failover not working correctly

I have Oracle 11gR2 set up on a RAC environment with two nodes. I have SCAN set up, eg: I have two entries on the DNS set up so I can ping the SCAN name and reach either node. I can also ping both ...
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1answer
2k views

Do I need to enumerate the columns used in a materialized view when creating the MV log?

I'm currently creating materialized view logs on a whole bunch of tables in order to support materialized views with FAST REFRESH. The materialized views we're creating contain approx 30 columns from ...
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664 views

Bad use of Oracle Tablespaces

I have a doubt about the use of oracle tablespaces. I've decided to define for each schema of the datababase two different tablespaces (one for data, and another one for indexes). The problem is that ...
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3answers
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Unable to start Oracle (11g1) due to bad memory configuration (ORA-00837)

I decided to reduce the memory allocation of a local developer instance, and was told that the following command did the job; alter system set memory_max_target = 512M scope = spfile; Which I guess ...
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2answers
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Clean trace files on Oracle 11g

The partition containing my Oracle 11g installation began to fill up with trace files and when I went looking for what are these I've found this disturbing post about how to disable the trace file ...
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Database logon trigger

To block a particular user and IP combination on an Oracle Database , I created the following trigger, and compiled without errors. Create or replace trigger you_may_not_login after logon on database ...
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Where can I find autoextend events?

In Oracle, where can I see the history of DBFs autoextending? Or get the timestamp that a DBF last autoextended, and by how much?