Speaking at Delphix User Group Webex March 11

On March 11 at 10 am California time I will be speaking in a Delphix User Group Webex session.

Here is the sign up url: WebEx sign up.

Adam Leventhal, the Delphix CTO, will also be on the call previewing the new Delphix 4.2 features.

I will describe our experience with Delphix and the lessons we have learned.  It is a technical talk so it should have enough details to have value to (more...)

A new index on a small table makes a big difference

A few weeks back on the weekend just before I went on call we got a complaint about slowness on an important set of reports.  I worried that the slowness of these reports would continue during my support week so I tried to figure out why they were slow.  I reviewed an AWR report for the 24 hours when the reports were running and found a simple query against a tiny table at (more...)

Long parse time with interval partitioning and subpartitions

In an earlier post I described how some queries with long parse times were causing long library cache lock waits.  Friday I applied a patch from Oracle that resolved the long parse times.  Here are the conditions which may relate to this bug:

  1. Interval partitioned table
  2. Partitioned by range
  3. Sub-partitioned by list
  4. Open ended range on partitioning column in where clause
  5. Tens of thousands of sub-partitions

Prior to applying the patch I did (more...)

Arizona User Group Meeting tomorrow

Here is the link: url

It looks like our meeting tomorrow will be on Oracle 12c new features.  I’m looking forward to participating. :)

– Bobby

Cary Millsap

This is my third of four posts about people who have made a major impact on my Oracle database performance tuning journey.  This post is about Cary Millsap.  The previous two were about Craig Shallahamer and Don Burleson.

I am working through these four people in chronological order.  The biggest impact Cary Millsap had on me was through the book Optimizing Oracle Performance which he co-authored with Jeff Holt.  I have (more...)

Career Day – Oracle Database Administrator

I will be talking at my daughter’s high school for career day on Monday, explaining my job as an Oracle Database Administrator.  Wish me luck!

The funny thing is that no one understands what Oracle DBAs do, unless they are one or work closely with one.  I have a feeling that my talk is going to fall flat, but if it helps one of the students in any way it will be worth (more...)

AZORA – Arizona Oracle User Group meeting January 20th

AZORA is planning a meeting January 20th.  Here is the link to RSVP: url

Hope to see you there. :)

– Bobby

10128 trace to see partition pruning

I am working on an SR with Oracle support and they asked me to do a 10128 trace to look at how the optimizer is doing partition pruning.  I did some quick research on this trace and wanted to pass it along.

Here are the names of the two Oracle support documents that I found most helpful:

How to see Partition Pruning Occurred? (Doc ID 166118.1)

Partition Pruning Min/Max Optimization Fails when Parallel (more...)

Parsing blocks stats blocks parsing

I had a five-minute conversation with Oracle development Friday that rocked my world.  I found out that parsing blocks stats which blocks parsing.

We have a system with queries that are taking minutes to parse.  These queries include the main tables on our database, one of which is interval partitioned and has 20,000 sub-partitions.  We have seen a situation where Oracle’s delivered statistics gathering job hangs on a library cache lock waiting (more...)

Alerting on plans that change for the worse

I’ve uploaded a monitoring script that I have worked on: zip.

The script alerts you when the optimizer runs a SQL statement with a potentially new and inefficient plan so you can intervene.  This script improves upon my earlier script which only alerts you to SQL statements running with new plans.  The new script compares the average elapsed time of the current plan with the average of the most often executed plan.  (more...)