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Redo Logfile Size Advisor

The Redo Logfile Size Advisor can be used to determine the least optimal online redo log file size based on the current FAST_START_MTTR_TARGET setting and MTTR statistics.
Which means that Redo Logfile Size Advisor is enabled only if FAST_START_MTTR_TARGET is set.
The Advisor provides a recommended optimal smallest online redo log file size.
we can then adjust the online redo log file size to the recommended optimal size ,eliminating the need to manually determine an optimal size.

To use the advisor we need to query the V$INSTANCE_RECOVERY VIEW.

If our redo log file size is under sized then the checkpoint process is driven by WRITES_LOGFILE_SIZE i.e. its driven by the smallest redo log file size.

Automatic Work Load Management and High Availability

Automatic Work Load Management

Application workloads can be defined as services so that they can be individually managed and controlled.
We can control and monitor which processing resources are allocated to each service during both normal operations and in response to failures.
Performance metrics are tracked by service and thresholds set to automatically generate alerts should these thresholds be crossed.
CPU resource allocations and resource consumption controls are managed for services using Resource Manager.
we deifne rules to automatically allocate processing resources to services. Oracle RAC 10g instances can be allocated to process individual services or multiple services as needed.

Understanding Explain Plan

Benjamin Disraeli, circa 1870 wrote:
Never complain and never explain.

Disraeli was a lot of things, but Oracle Programmer was not amongst them. To be fair, perhaps he wasn't talking about Explain Plan?

SQL is a goal-oriented language. Unlike procedural languages, we tell the database what we want rather than how to get it. Oracle's Cost Based Optimizer comes up with an execution plan that is hopefully the most efficient way to resolve the query, but for many reasons it will often choose a sub-optimal plan.

Getting information about previously run commands with statspack

cbruhn2's picture


When you setup statspack with level 6 you can have information on the sql_plan associated with a sql. (statpack on oracle db version >=9i)

"Fixing" SYS for hacking purposes

How does one change Oracle's SYS password without having to login into the database? Is it possible?
The answer is, YES! All you need is a binary fiile editor and some knowledge of Oracle's internals.

This document is to be used only for testing purposes and should not be used in a production environment. The purpose is to show the audience how hackers can gain access to your system without knowing it - and how to prevent it.

Timing an ALL_ROWS query

The Problem

A common complaint in SQL is that "it runs in 5 seconds in SQL*Plus, but takes hours in Production. Why?"

The reason is because SQL*Plus and most GUI SQL tools display rows as soon as they are fetched. In this way, you can SELECT * FROM big_big_table and it will display the first 20 or so rows in the table in a fraction of a second, then go back for more. The SQL is not really finishing in seconds; if you timed how long it took to retrieve every row, you'd see that it takes just as long as in Production.

How to avoid primary key collision on multiple sites?

This article provides several comparative methods to avoid primary key conflicts across multiple sites.

Enabling plan_sql from statspack

cbruhn2's picture


When you setup statspack with level 6 you can have information on the sql_plan associated with a sql.

Understanding Indexes

Of iPods and Indexes

I'm not really an "early-adopter" of technology. Don't get me wrong; I love it, I just don't want to feed the addiction. When I do get a new piece of technology though, it's like a fever; I can't concentrate on anything until I've read the manual from cover to cover and found out everything it can do, every built-in gizmo, and every trashy piece of after-market merchandise that can be plugged into it.

And I don't think I'm alone here.

PL/SQL Tuning for Batch Systems

A History Lesson

Where were you in 1990? Nelson Mandela was being freed from Victor Verster Prison after 26 years behind bars, Saddam Hussein was starting the Gulf War by invading Kuwait, and Tim Berners-Lee was inventing the World-Wide-Web at CERN in Geneva. Me? In 1990, I was writing an insurance system in Oracle SQL*Forms v2.3.