Server Administration :: Limitations Of Database Links
Jan 25, 2012
I'm currently assessing the design/performance of a Distributed System in which hundreds of Field reps have local Oracle DBs (10.2.0.4) on laptops & have to update a remote database (11.2.0.1) via a PUBLIC database link. Field data (millions of records) collected daily is synched from the local to the remote DB & vise versa through this database link. I have 2 concerns here:
1. Is the database link the best option for such a configuration? (recently field reps have been complaining about the slowness in synchronizing data between local & remote DBs). If not, what other options are available for such processing?
2. I've read a lot about security concerns with using PUBLIC database links, but haven't seen any documents to proof they're a majority security issue. why PUBLIC database links are considered not to be very secure?
I have read following statement from a link [URL]...
Oracle Database XE can be installed on any size host machine with any number of CPUs (one database per machine), but XE will store up to 4GB of user data, use up to 1GB of memory, and use one CPU on the host machine.
calculation of this 4GB size. how can we calculate this size?
by simply going to DBF file and seeing their size? or by exporting dump and seeing the size of that dump?
I downloaded the oracle 11g R2 from oracle site. I am using the database for tests in one machine there are 5 months and it works normally (with all features).
My question is, what limitations of this database? What's prevents me to use this db in production environment?
I am trying to retrieve info from multiple DBs and insert into a central DB via DB LINKS.The links are retrieved via a cursor.
However I keep coming up against 'PL/SQL: ORA-00942: table or view does not exist'..how to handle db_links using a cursor in a pl/sql block? The code is as follows:
DECLARE db_link_rec VARCHAR2(30); CURSOR db_link_cur IS SELECT DB_LINK from MESSAGING_PROD_LIST; BEGIN OPEN db_link_cur; LOOP FETCH db_link_cur INTO db_link_rec; EXIT when db_link_cur%NOTFOUND; [code]....
I am using SQL Developer.I am self-teaching myself PL/SQL. What I am trying accomplish is to run a select query across many database links at runtime and to insert that query onto a local table. So far, I have only gotten as far as querying the database link names. I am stuck at where my variable calls the database link name. It does not recognize the database link name, and I can't quite grasp the reason why. Below is the first part of my script which does retrieves the column values no problem:
If I break the script down to the bare select query, it will query absolutely fine.If I run the script in its entirety, it will not pick up the variable dbl as a dynamic database link. 02019. 00000 - "connection description for remote database not found"
If I comment out line 031 and prevent the looping of querying of database links (which will only fetch the first value of db_link from dba_db_links), the script will complete and I will have a row inserted into my local table.
I am suspecting it's the looping that is incorrect but I understand it is not going to do anything beyond line 059.
A website requires to display consolidated data from databases located in different geographical regions (India, London and New York). The application server for the website is hosted only in one location India. What are the techniques that can be used for faster retrieval of data from all 3 databases?
Note: There is no need of real time data retrieval from different regions; however the user should able to view the updated data at predefined intervals.
I know how to use database links in various forms, but I've been trying to think through how the authentication works for a connected user link in 11g. If I create the link like this,
create public database link using 'orcl';
then any user can use the link, provided they have an identical username/password in the two databases. With pre-11g passwords, it was understandable: the password was salted with the username, so the hash of the password would be the same in both databases, and I assumed that the logon through the link used some sort of IDENTIFIED BY VALUES mechanism. But in 11g, the salt will different in the two databases. So the hash will be different. And of course Oracle never stores the actual password. So I don't see how the authentication works.
I would like to know if we can insert 300 million records into an oracle table using a database link. The target table is inproduction and the source table is in development on different servers.The target table will be empty and have its indexes disabled before the insert. if this can be accomplished in less than 1 hour.
I know how to use database links in various forms, but I've been trying to think through how the authentication works for a connected user link in 11g. If I create the link like this,create public database link using 'orcl';then any user can use the link, provided they have an identical username/password in the two databases. With pre-11g passwords, it was understandable: the password was salted with the username, so the hash of the password would be the same in both databases, and I assumed that the logon through the link used some sort of IDENTIFIED BY VALUES mechanism. But in 11g, the salt will different in the two databases. So the hash will be different. And of course Oracle never stores the actual password. So I don't see how the authentication works.
i am installing oracle database 8.1.7 on dell server power edge 2650 first time database successfully installed but when i want to crate new database by Database Configuration Assistant it is not working for new database creation.
i am trying to install Oracle 10.10.2.0 on Windows Server 2003 standard x64 Edition Service Pack, but when i try to run the installer or open DVD it gives me below error.
"The image file D: is Valid, but is for a machine type other than the current machine."
I have to migrate production database version 10gR2 on windows 2003 server to oracle 11gR2 on windows 2008 server . So far i have just installed the oracle software on 64bit windows 2008 server. How to move the data or migrate from old server to new server .
I am trying to find the unix process for one of my application in the database but I am unable to view the same. To simulate, I did the following.
1. My database runs on different server. 2. I invoked "sqlplus" from another unix box to login to the database. 3. I found that the process id (ps -ef |grep sqlplus). 4. When I execute the below mentioned query it does not display the process id that I am looking for. But the osuser, username, program and machine details are correct. How can I know the process details from the database?
SELECT SYS.GV_$SESSION.OSUSER, SYS.GV_$SESSION.USERNAME, SYS.GV_$PROCESS.SPID, SYS.GV_$SESSION.MACHINE, SYS.GV_$SESSION.PROGRAM, SYS.GV_$PROCESS.PROGRAM ,SYS.GV_$SESSION.SQL_ID FROM SYS.GV_$PROCESS, SYS.GV_$SESSION WHERE SYS.GV_$PROCESS.ADDR=SYS.GV_$SESSION.PADDR and SYS.GV_$SESSION.USERNAME='TEST' and SYS.GV_$SESSION.MACHINE like '%hostname%'
I have database in single server. I already have ORACLE_SID=stagedb. So i want to create new sid and named as proddb.Is it possible have multiple db in single server? This server not running as RAC. It run as single only.
database administration , we are planning to use amazon cloud database , this database does not allow us to login to server machine , unfortunately amazon don't provide ssh to this machine , in general for doing any of adminstration task on the database will there be need to log into the machine ? we can always log in through toad or any other sql client but we cannot do ssh to server..general can this limitation effect administration ?
I recently installed Oracle 10g on my windows Xp laptop. It has become considerably slow since then. I want to start the database server only when I need it, and not every time I start my laptop. I looked around in OEM and did found a way.
I am connected as System. It was the only user I set-up a password when installed the database on personal computer.
SQL> alter user sys identified by mypass007 2 / User altered. SQL> connect sys/mypass007 ERROR: ORA-28009: connection as SYS should be as SYSDBA or SYSOPER
We have an Oracle Server database of Size 50 GB having 10 GB Data. And Planning to have a new Database Server of 200GB . So my question is after moving all the 10 GB data to 200 GB Database Server, will the performance of the system come down? Will it reduce the speed?
Can I extract data from our Oracle server regarding the no. of sessions per day? But the problem is that our Boss wants a previous dates from April 11-17, 2011.
I have some requirement wherein I need to install Oracle 9i database server (9.2.0.7). I am not getting it on Oracle website. where can I get the download.
I am trying to do a Flash Chart in APEX 3.1. Is there a limitation on how many labels I can get horizontally. No matter what I do the number of labels I get horizontally is 15. We are trying to show the amount of days in a month.... Can I do that? If so how?
see as i said keep on my database down in the night time around 9 pm. the OS redhat linux 5 restarting morning around 6.45 am.when i check alert_log there is no indication.when i check OS log , OS restarting around 6.45 amchecked in the log file in OS level
location: /var/log
i found this
Jun 7 06:45:33 Alraya syslogd 1.4.1: restart. Jun 8 06:42:22 Alraya syslogd 1.4.1: restart. Jun 9 06:47:12 Alraya syslogd 1.4.1: restart.
what is this mean, system restarting around 6:45 daily i think now i m posting listener.log for reference
OS is restarting around 6.45 in the morning, but database getting down night around 9 pm itself why then in the morning if i bounce the database it starting with no problem
