Author Archives: Bobby

Oracle support recommends setting the hidden parameter _unnest_subquery to FALSE to improve the performance of PeopleSoft applications on Oracle databases.  I’m trying to understand the consequence of changing this parameter from its default setting of TRUE. PeopleSoft applications have a … Continue reading →

In an earlier post I described the process that I go through to check the plans of production SQL queries to see if they change when you do a system upgrade or patch.  Today I’ve been following that process to … Continue reading →

We usually use locally partitioned indexes on partitioned tables.  Many of our data warehouse tables are partitioned by date and partitions get added or removed over time.  It is much easier to maintain the indexes on this kind of table … Continue reading →

I’ve uploaded a sql script that gets an AWR report for yesterday, a week from yesterday, and four weeks from yesterday for the same time period – 10 am to 4  pm. I’ve been manually reviewing the previous day’s AWR … Continue reading →

I’m helping a coworker learn how to do Oracle performance tuning and today I think we found some good documentation on which V$ views to use for tuning which can also help with reading an AWR report.  In a previous … Continue reading →

I’ve known for a while that if you have an Exadata table compressed with Query High compression and you want to load data into it and have it be compressed as it is loading you have to use direct path … Continue reading →

A coworker of mine just brought a new hint to my attention – the APPEND_VALUES hint.  I’m used to the append hint which makes insert statements use direct path instead of conventional loading.  Here is what the old standby append … Continue reading →

I’m at the East Coast Oracle Users Conference and wanted to write a blog post about the first day, which is now done.  Rather than summarize all the sessions I thought I would focus on what struck me the most … Continue reading →

I just found out that my alternate talk for the East Coast Oracle Users Conference is needed.  So, I’ll be doing my Exadata talk on Wednesday and my Intro to SQL Tuning talk Thursday.  This makes the conference even more … Continue reading →

I was working on a package that we use to gather statistics on the partition level after data is loaded and found some quirks that apply when the partition has subpartitions. You can’t use dbms_stats.gather_table_stats to gather stats on just … Continue reading →