ALL POSTS

21-hours Phantom SELECT Causing ORA-1555 ‘snapshot too old’

One of our clients had an ORA-1555 “snapshot too old” error two nights in a row. The quick and dirty fix would be to increase the retention_period and the potential size of the UNDO tablespace. I was looking at it together with Dave, my new team mate, and a small detail popped up right away — Query Duration=76584 — 21+ hours? I checked the retention period, and it was 2 hours, so the dirty fix would probably fail unless it’s very dirty — dumping undo retention to something like a day and blowing the UNDO tablespace, and still without guarantee that the query finish within a day.

‘plus archivelog’ and RMAN optimization

I just want to raise a warning flag for DBAs using RMAN and flash recovery area in Oracle 10g. The lesson is, to avoid backing up archivelogs that have already been backed up when using plus archivelog in a backup script, make sure you enable RMAN optimization.

What is Behind Pythian’s Growth and Market Success?

This is more of an essay than a blog post, but this subject comes up time and again, and since I tripped across this interesting blog post by Pedro Timóteo about why he has decided not to be a sysadmin any more, I thought now’s as good a time as any to comment on what I think is a significant industry trend in production engineering work.

Are you tired of weak, crappy coffee?

Several months ago, I started to once again drink that elixir of the Database Gods. Now that I am beginning to drink coffee again, I can really appreciate Jon Emmons’s humor in naming his blog site www.lifeaftercoffee.com. Truly, a DBAs work life does NOT begin until after coffee.

Reporting Space-Wasting Objects in Oracle

I chose to talk about a technique I used at a client’s site to report the topmost space-wasting objects in an Oracle database. I was looking for a way to detect these objects without having to run some expensive analyze statements or dbms_stats jobs. I found out that I can use the dbms_space package to do this. It worked very well for me and I’m sure lots of DBAs could use this technique too.

The Dirty Dozen #10: Stress

Number 10? I only just finished Dirty Dozen #1. What’s going on here, then? Well, no one said I had to write them in any particular order! But, if you look at the posters, they are clearly numbered. Should someone else pick up the Dirty Dozen challenge, it will help them to see which ones…

IOUG Collaborate 07: Oracle Block Change Tracking Internals

I first presented on Oracle 10g Block Change Tracking Internals at UKOUG 06 in Birmingham. It was very well received, but there were quite a few gaps in my knowledge, and I later discovered I was incorrect in some places. I’ve done some additional research, filled in the blanks and corrected in a few places. Download it here.

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