ALL POSTS

mysql> set global innodb fast=true;

So you ran into some basic limitations with MyISAM when your site got busier. Even single row updates would lock the whole table and slow things down to a crawl. Then you updated to InnoDB to get the benefit of row-level locking, but now the site is even slower than before. What gives? Here’s whats happening….

Using Block Dumps to Read Uncommited Transactions

My team and I still use old-style rollback segments for one of my client’s 10g production databases. We just never found the need to switch to automatic undo management. There are a number of 1GB rollback segments. They are that size because they need to be able to support large transactions. At the same time, we don’t want to have transactions bigger than 1GB as this is an OLTP system. For the past few weeks we’ve had a strange problem. One of the web calls would cause one of the rollback segments to become full by using 1GB of undo data.

Battle Against Any Guess

Greetings everyone. I would like to announce that last weekend the BAAG party was born. If you are tired of observing troubleshooting by guessing day by day, by day, by day, by … — join the forces of BAAG party. We can make a difference together! See you there.

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.

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