Search Results for: SQL Profile

Improving performance of top query

I’m on call this week. Here are the steps that I took to speed up a query today. First I got an AWR report and found the top query. Also, someone from support told me to look at November 11 before … Continue reading

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Comparing Common Queries Between Test and Production

The developers complained that their test database was so much slower than production that they could not use it to really test whether their batch processes would run fast enough when migrated to production. They did not give me any … Continue reading

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Plan change monitor prevents user impact from bad plan

This morning a colleague of mine noticed an alert from our plan change monitor and prevented any impact on the users by forcing a SQL’s plan to its normal fast plan before the users could be affected.  I want to … Continue reading

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Simple test of DB server CPU speed

I’m trying to compare two types of database servers and it looks like one has a faster CPU than the other.  But, the benchmark I have used runs a complicated variety of SQL so it is hard to really pin … Continue reading

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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 … Continue reading

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Useful Carlos Sierra post about queries changing performance

Saw an interesting post related to work I am doing locking in plans and finding plans that have changed: Carlos Sierra post on queries with changing performance. Our DBA team uses versions of my sqlstat.sql(updated) script to find queries whose … Continue reading

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Library cache lock scripts for RAC

I’ve been having issues for a long time now with an Exadata RAC database that has user reports experiencing library cache lock waits.  The challenge is to figure out what is holding the library cache locks that the queries are … Continue reading

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Don’t use TIME_WAITED in ASH views

I attended John Beresniewicz’s Active Session History (ASH)  talk at Collaborate 13 on Monday.  One simple point from it was that he commonly sees queries of the ASH views that use the TIME_WAITED column incorrectly and result in incorrect results.  … Continue reading

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Faster commit time with shared servers

This is a follow up to my previous post “Faster commit time with fewer sessions“.  I’ve put together a test case against an HP-UX server running 10.2.0.3 of Oracle that shows commits six times faster with shared servers than with … Continue reading

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Faster commit time with fewer sessions

I’m trying to understand how to prevent the database server that supports one of our web sites from becoming overwhelmed when the CPU %used gets too high.  Once CPU gets above about 80% performance takes a nose dive and CPU … Continue reading

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