Category Archives: Uncategorized

Hopefully this is not too redundant to previous posts but I’ve found that I keep using a particular script to debug performance issues and I thought I’d share it and explain what I use it for.  It’s helpful to me … Continue reading →

Today I saw two different plans with the same plan hash value but different numbers of partitions.  So, the partition numbers must not factor into the plan hash value.  So, you can’t count on the plan hash value to fully … Continue reading →

So,  I play one computer game – Nethack.  I have a page on the blog if you want some information about it.  I just finished building a 32 bit Linux virtual machine running on VMware player for the purpose of … Continue reading →

I wasn’t sure if people would find a post on a bug that interesting.  If you don’t have the same bug I’m not sure what you would get out of it.  But, it is what I’m working on. Here are … Continue reading →

I’m on call this week so I didn’t plan to do any blog posting but I had an interesting performance issue this morning that I thought would be helpful to document.  This is somewhat redundant to earlier posts but maybe … Continue reading →

Another simple script: zip. This is like an AWR report where you see a difference in v$ view values over time.  But, it is for  one wait event over a single interval.  Simple but possibly useful. drop table waitdiff; create … Continue reading →

I’ve taken a script I use to show a particular wait event over time and parameterized it a bit to make it more general. Here is a zip of the script: zip(updated). This is the same sort of information you … Continue reading →

I modified the example from my previous post to see if on Exadata I could denormalize two tables and get the same performance without an index on the denormalized table that I get with the index on the normalized ones. … Continue reading →

I was working on the example from an earlier blog post that showed how the optimizer could not correctly estimate the number of rows accessed on a table if the non-join condition was on a different table.  Number of rows … Continue reading →

I have a table with interval partitioning and subpartitions and I want to extract the DDL including all the system generated partitions and subpartitions which get created as new rows with dates beyond the last partition’s high value get inserted. … Continue reading →