Category Archives: Uncategorized

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 →

Just found out that all the good documentation for the DBMS_METADATA package is in the Utilities manual.  I’ve just been looking at the “PL/SQL Packages and Types Reference” manual for the details of how to use DBMS_METADATA.  I’ve been handcuffing … Continue reading →

I thought I would do a fun “day in the life” blog post about the work I’m doing today.  And then chaos ensues! 8:22 AM MST  After starting this blog post and reading my email I updated my time card … Continue reading →

Well, I’ve been running SQLT all day.  I’ve got a case open with Oracle support on the issue described in my previous post.  Oracle support wants me to use SQLT to run one of the queries with the long parse … Continue reading →

You got to love Exadata and subpartitioned tables.  We have these queries on one particular table that are taking forever to parse.  Sometimes a simple explain plan on the simplest possible query against the table takes 20 or 30 seconds.  … Continue reading →

I’ve been working on testing performance on a database that uses Delphix as its storage system and ran across an unexpected side effect of using Delphix to clone a production database for testing.  Because Delphix uses NFS to present the … Continue reading →

I haven’t figured out the best way to do this yet so this is a work in progress.  I’m trying to document the process of taking a large query that joins many tables together and breaking it into a series … Continue reading →

I had a situation today where I had two slightly different queries that I thought should have the same plan but they didn’t.  So, I needed a way to force the slower query to run with the same plan as … Continue reading →