Donald K. Burleson's blog

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AWR and SQL Tuning

The AWR tables contain super-useful information about the time-series execution plans for SQL statements and this repository can be used to display details about the frequency of usage for table and indexes. This article will expore these AWR tables and expose their secrets.

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Can you have too much cache?

There is a great debate about the rapidly-falling costs of RAM and the performance benefits of full caching of Oracle databases. Let's take a closer look at the issues over large RAM data buffers, tuning by adjusting system parameters and using fast hardware to correct sub-optimal Oracle code:

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Oracle first_rows optimization improvements

Prior to Oracle9i, the only two cost-based optimizer modes were all_rows and first_rows optimization. One of the shortcomings of traditional first_rows SQL optimization was that the first_rows goal did not know the scope of the query and generally favored index access over full-table scans.

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The new Oracle10g Wait Event Tables

Prior to Oraclre10g, capturing wait event information was a cumbersome process involving the setting of special events (e.g. 10046) and the reading of complex trace dumps. Fortunately, Oracle10g has simplified the way that wait event information is captured and there are a wealth of new v$ and wrh$ views relating to Oracle wait events.

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Extending Oracle10g AWR

Oracle10g Enterprise Manager (EM) has a fantastic interface for easily creating exception alerts and mailing them directly to the Oracle professional. However, the EM has limitations. Until EM evolves into a true Decision Support System (DSS) for the Oracle DBA, the DBA will still need to extract and use the workload information stored in the AWR (Advanced Workload Repository).

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Tuning Oracle Full-table Scans

Oracle SQL tuning is one of the most important areas of Oracle optimization. This article explains how one can tune Oracle Full-table Scans.

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Avoid common Oracle Recovery mistakes

Even Oracle Certified DBAs cringe at the thought of performing a real-world database recovery. As disk and hardware has become super-stable, many Oracle DBAs have never experienced the adrenaline rush of a full-blown Oracle recovery.

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Always use direct I/O with Oracle

Many Oracle shops are plagued with slow I/O intensive databases, and this tip is for anyone whose STATSPACK top-5 timed events shows disk I/O as a major event.

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Improved 10g management with EM

Just a few years ago, many senior Oracle DBAs detested Oracle Enterprise Manager (EM). Viewed as a crutch for beginners who could not memorize the command syntax, EM was largely ignored by the veteran DBA who preferred the ease and certainty of the SQL*Plus command-line interface. This is about to change.

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Unconventional Emergency Oracle Support

Being an emergency support DBA is a job with huge stress-levels and it always provides a giant adrenaline rush for even the most experienced DBA. Senior management is in a panic, and high-level executives are continuously asking for a status update. Most of these databases are brand-new to me, and I have only a few minutes to access the situation and devise a plan to quickly relieve their bottleneck.

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