Showing posts with label SQL Tuning. Show all posts
Showing posts with label SQL Tuning. Show all posts
Tuesday, December 20, 2011

Detect Row Chaining, Migrated Row and Avoid it

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--------detecting chained row----- This query will show how many chained (and migrated) rows each table has: SELECT owner, table_name, chain...
Wednesday, October 6, 2010

When to Rebuild an Index?

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When to Rebuild an Index? It is important to periodically examine your indexes to determine if they have become skewed and might need to be ...
Thursday, August 5, 2010

SQL Performance Tuning Tips

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SQL Performance Tuning 1. Use EXPLAIN to profile the query execution plan 2. Use Slow Query Log (always have it on!) 3. Don't us...

Stored Outlines

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Stored Outlines Oracle preserves the execution plans in objects called “Stored Outlines.” You can create a Stored Outline for one or more SQ...
Wednesday, August 4, 2010

AutoTrace

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Prerequisites SQL> @ORACLE_HOME\rdbms\admin\utlxplan.sql This creates the PLAN_TABLE for the user executing the script. ---------- Settin...

Cost Based Optimizer (CBO) and Database Statistics

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Cost Based Optimizer (CBO) and Database Statistics The mechanisms and issues relating to maintenance of internal statistics are explained be...

Explain Plan

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SQL> @ORACLE_HOME\rdbms\admin\utlxplan.sql This creates the PLAN_TABLE for the user executing the script. Run EXPLAIN PLAN for the query ...
Tuesday, August 3, 2010

SQL Trace / TKPROF

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To start a SQL trace for the current session, execute: ALTER SESSION SET sql_trace = true; ALTER SESSION SET sql_trace = true; or DBMS_SYSTE...