Amardeep Sidhu's Tech blog

Today, I was following a thread on Oracle Forums. Someone asked a question about UNDO tablespace wrt to a scenario. The question was: There is a database and its hot backup is taken on Friday. Now for Saturday, Sunday and Monday there are archive logs but no backups. Suppose the machine crashes on Monday. After we restore the database to Friday (from backup), recovery will happen. As UNDO tablespace is of Friday so it has no information related to transactions that happened on Saturday, Sunday and Monday. So in the end of recovery process when we need to rollback some transactions from where that required information will come ? ...

Being a new kid on the block, I think, my post will not fire any serious and “scary” discussion as it has happened many times in the past. Just writing my experience. Whenever I search something related to Oracle in Google there are few sites that are bound to come up in the very first results ( No surety about the relevance and completeness of the content, though). Today I was searching about scheduling new jobs in oracle and I was, sort of, surprised to see the results [Though, I got from there, what I was looking for & I would like to say Thanks for that]. Many other times also, I have seen these websites pop up like anything. ...

I was searching for some good tutorials on awk. Found a very nice (brilliant indeed) article on Oracle website by Emmett Dulaney. A very good introduction for beginners. I searched for some other links as well. Have a read: 1. AWK: The Linux Administrators’ Wisdom Kit 2. A Guided Tour Of Awk 3. AWK Programming 4. UNIX Utilities - awk Happy awk’ing :) Sidhu

Today Stumble gave me a link to an article on a website. That article talks about a guy Virgil Griffith who wrote a piece of software to track IP addresses of the people, editing the Wikipedia content. Some really interesting things came up: Apple attacking Microsoft and then Microsoft taking revenge. Have a look at the full article. It makes an interesting read. Read more about this guy on Wikipedia here. Sidhu

Few days back, I had to give Oracle DBA training to a group of about 20-25 semi-technical people (Semi-technical, because most of them were not really DBA kinda folks doing all the techie stuff with Oracle, but in-fact having learned some bits & bytes of Oracle sometime back and these days looking into application functionality from technical perspective). I, having just about 10 months of experience with DBA profile, had to cover, everything about Oracle starting from creating database and up to performance tuning :) Its really an interesting job if the audience is good. But not an easy game. You have to know everything and have to be ready to answer people’s queries (some stupid & dumb questions also :) I had to cover a total of about 350 slides in a day or less. So at times, really went fast and skipping some of things. It was a nice experience as a whole :) ...

Many times, we are required to restore a database from an export dmp file. Its a simple task but sometimes there are some issues left like invalid objects or some objects missing, in the newly created database. Following steps, followed in order can help in creating an error free database: Create a blank database:The very first step is to create a blank database which is to be used as the target database. That can be done using Database Configuration Assistant. (In last step of the DBCA, change redo log file sizes to 500 MB each (or some appropriate values depdening upon the size of the databaes), as during import, lot of redo will be generated, so large redo size helps in that scenario) ...

The day when Oracle 11g was made available for download on OTN, there was sort of, flood of posts in the Oracle blogsphere. Here is a quick recap of few of the posts (Whatsoever I could find through OraNA and my Netvibes) Eddie Awad about 11g, I think he was the first one to post Then Doug Burns here Howard on installing 11g Another interesting article from Howard Tim Hall about 11g Tim Hall on installing 11g ...

I have been installing Linux for last 6 years and for more than half the number of times, came across a message something like “This partitions is beyond the 1024 cylinder boundary and may not be bootable”. But never cared for it much and understood what exactly it meant to say ? Yesterday I was reading System Admin guide to Linux by Lars Wirzenius (Thanks Howard for the link :) From there I came to know what exactly that message meant. Quoting from the guide itself: ...

Last to last week, we shifted to a new house. As there was no internet connection, so we were without any internet access for last 2 weeks. Today we got the new internet connection. Its a DSL one. And the guy who came to do the installation threw a little bit of technical jargon like rebooting the router and so on. It feels so good to be back in the world of www :) ...

Many times you need to move datafiles from one location to another. The simplest approach for this is to take the tablespace offline, copy the datafiles to new location, rename the files with alter database rename file (Except that you dont have to move the SYSTEM and UNDO tablespace, as you can’t take SYSTEM tablespace offline) [sourcecode language=‘css’] SYS@orcl AS SYSDBA> alter tablespace system offline; alter tablespace system offline * ERROR at line 1: ORA-01541: system tablespace cannot be brought offline; shut down if necessary ...