Category Archives: Uncategorized

Shared servers prevents web outage

This weekend we had the most convincing evidence that our change from dedicated to shared servers on a database that supports a farm of web servers was the right move.  We have had some outages on the weekend caused by … Continue reading

Posted in Uncategorized | 6 Comments

Proc to run a long select statement

I’m trying to test some select statements that have some lines longer than 4000 characters and I couldn’t get them to run in sqlplus so I built this proc to run a select statement that is stored in a CLOB … Continue reading

Posted in Uncategorized | Leave a comment

Dynamic sampling hint better than multi-column histogram

One of our senior developers found a way to greatly improve the performance of a query by adding a dynamic sampling hint for a table that had multiple correlated conditions in its where clause.  This led me to try to … Continue reading

Posted in Uncategorized | Leave a comment

putty the publisher could not be verified Windows 7

So, this isn’t really Oracle related except that I got a new Windows 7 laptop to support Oracle and I’m getting an annoying popup message every time I try to run putty to access a database server. I looked up … Continue reading

Posted in Uncategorized | 8 Comments

Finally up on Oracle 12c

So, I had to get a new work laptop to install Oracle 12c.  I was on Windows XP and even though I knew my company would have paid for me to get a new one a long time ago I … Continue reading

Posted in Uncategorized | 4 Comments

List tables that stats job doesn’t finish

We are running the Oracle delivered automatic optimizer stats job on some of our 11.2 Oracle databases and the job is not completing for some of our tables.  But, the list of these tables is buried in a trace file … Continue reading

Posted in Uncategorized | 1 Comment

Shared servers results in lower CPU usage for top query in AWR

In two previous posts I’ve discussed the possibility of switching from the default dedicated server configuration to shared servers to support a large web farm. The original post I decribed how Tom Kyte recommended a Youtube video that champions reducing … Continue reading

Posted in Uncategorized | 4 Comments

Moving to 64 bit laptop OS to run Oracle 12c

I wanted to download the new version of the Oracle database software to test it out but I have an old laptop running Windows XP, a 32-bit OS.  So far Oracle hasn’t released a 32-bit Windows or Linux version on … Continue reading

Posted in Uncategorized | Leave a comment

Using coe_xfr_sql_profile.sql to force a good plan

Sunday night we worked with Oracle Support on a performance issue with a query that had been running for over 14 hours even though it ran the previous weekend in five minutes.  Oracle Support showed us how to use coe_xfr_sql_profile.sql … Continue reading

Posted in Uncategorized | 12 Comments

Cardinality errors across joins

We have been discussing query tuning at work and I’ve come back to an example of the Oracle optimizer choosing the wrong plan due to an error in its calculation of the number of rows returned by a query.  I … Continue reading

Posted in Uncategorized | 6 Comments