Posts by Alex Gorbachev

How Not to Use Shell Commands

Here are a few nice typos that had quite disastrous consequences. After having fought some network problems to get a distribution of Oracle installation binaries from OTN to a Linux box, a colleague found a revolutionary way to unpack a cpio archive. Have a look.

REMOTE_LOGIN_PASSWORDFILE=EXCLUSIVE in Oracle 10g

I’ve never really liked the idea of REMOTE_LOGIN_PASSWORDFILE=SHARED, probably just because I haven’t seen much use for it. As a result, I’ve never paid any attention to it. If you don’t recall the difference between EXCLUSIVE and SHARED settings for 9i, here is the quote from the documentation.

Forensic DBA: Oracle LogMiner Helps Detect Sabotage

One of our customers contacted us to help them recover from a situation where one employee, departing the company, left behind quite a bit of hidden damage. We had an option to restore the database to a certain point in time and try to capture previous versions. Using LogMiner was another idea and, as we later saw, a superior one.. Log Miner is an extremely useful tool to investigate harm done to your databases, whether it was deliberate or not. In many cases you are able to use it for recovery too, even though it might not be directly available.

“ORA-1652: Unable To Extend Temp Segment” in RAC

Today I’ve seen a question on OTN forum about ORA-1652 in alert.log in RAC environment. I immediately recalled the bug and thought that I should mention that here. I quickToday I’ve seen a question on OTN forum about ORA-1652 in alert.log in RAC environment. I immediately recalled the bug and thought that I should mention that here. I quickly found Metalink Note 258941.1 and was surprised to see that there are actually two bugs on that and I only was aware of one so I definitely have to blog about it now.ly found Metalink Note 258941.1 and was surprised to see that there are actually two bugs on that and I only was aware of one so I definitely have to blog about it now.

What Happens When You Leave an Oracle Database in Backup Mode

So one fine evening, there was a scheduled maintenance, and one of the databases didn’t shutdown cleanly (thanks to mis-configured Windows services, if I recall correctly). Consequently, the database crashed and later didn’t come back up.When I looked at it in the morning, the error message rang a bell: “Datafile 1 needs media recovery” in combination with the request for very old archivelogs.The moral of the story: do not leave datafiles in backup mode. If you use hot backups outside of RMAN, such as snapshot technologies, take care to implement monitoring so that the database doesn’t stay in backup mode for much time.

Changing Hostnames in Oracle RAC

Sometimes there is a desperate need to change hostnames for one or all nodes of an Oracle RAC cluster. However, this operation is not officially supported. One way to do it is to remove a node from a cluster, change its hostname, and then add it back to the cluster as a new node. If you are brave enough, there is another way to do this. Find out here.

Oracle Coherence vs. Oracle RAC or Coherence + MySQL = MySQL RAC?

I came across Oracle Coherence today. Seems like this is another approach to clustering than Oracle RAC. Seems like this is a way to scale middle tiers that require shared data without actually using the central database for that. On the other hand, looks like a clustering framework with rules defined by developers as opposed to Oracle RAC that is designed and built to be a black box delivering database services. Has anyone (yeah, I’m asking developers reading the blog) played with it and knows how it feels?

MSDBF 07: Final Wrap Up

A few days ago, I did a short post about the start of the Miracle Scotland Database Forum 2007. I decided to wait until getting back home to complete a full-blown description of the event. I should warn you, this will be quite lengthy, so draw a deep breath.

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