I’ve waxed lyrical in the past about creating suitable column group statistics whenever you drop an index because even when the optimizer doesn’t use an index in its execution path it might have used the number of distinct keys of the index (user_indexes.distinct_keys) in its estimates of cardinality.
In my previous post, I discussed how you can now move heap tables online with Oracle Database 12.2 and how this can be very beneficial in helping to address issues with the Clustering Factor of key indexes. A problem with this technique is that is requires the entire table to be effectively reorganised when most of […]
We weren't sure we'd get Oak Table World for Collaborate going, but Bryn made sure that it happened, (better thank him when you see him!) We'll be in the South Seas C Ballroom all day Wednesday, so come learn database knowledge that everyone else is too frightened to talk about!
It is a great pleasure to announce the next Performance Days! This year the event will take place the 13-14 September in Zurich.
Given that detailed information about the event as well as online subscription are available at https://trivadis.com/performance-days-2017, in this short post I limit myself to thanking and pointing out who the speakers that accepted my invitation are:
I often get this type of question from customers and also from people I speak to and even a few times by email. The question is "can you tell us how secure our database is?", is it 10% secure, is....[Read More]
Posted by Pete On 23/03/17 At 03:22 PM
A question came up on the OTN database forum a little while ago about a very simple query that was taking different execution paths on two databases with the same table and index definitions and similar data. In one database the plan used the “index full scan (min/max)” operation while the other database used a brute force “index fast full scan” operation.
Our software product PFCLScan can be used to assess your Oracle databases for security issues that could make your data vulnerable to loss or attack. PFCLScan initially had its own website, PFCLScan.com but since the restyle and redesign of our....[Read More]
Posted by Pete On 22/03/17 At 08:24 PM
I ended up speaking at two events this last week. Now if timezones and flights weren’t enough to confuse someone, I was speaking at both an Oracle AND a SQL Server event- yeah, that’s how I roll these days.
One of the difficulties with trouble-shooting is that’s it very easy to overlook, or forget to go hunting for, the little details that turn a puzzle into a simple problem. Here’s an example showing how you can read a bit of an AWR report and think you’ve found an unpleasant anomaly. I’ve created a little model and taken a couple of AWR snapshots a few seconds apart so the numbers involved are going to be very small, but all I’m trying to demonstrate is a principle. So here’s a few lines of one of the more popular sections of an AWR report: