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May 2016

Debugging

The OTN database forum supplied a little puzzle a few days ago – starting with the old, old, question: “Why is the plan with the higher cost taking less time to run?”

The standard (usually correct) answer to this question is that the optimizer doesn’t know all it needs to know to predict what’s going to happen, and even if it had perfect information about your data the model used isn’t perfect anyway. This was the correct answer in this case, but with a little twist in the tail that made it a little more entertaining. Here’s the query, with the two execution plans and the execution statistics from autotrace:

Adding Twitter Handle to Time in Taskbar on Windows 10

So Uwe Hesse caught my interest when he blogged about how to add your twitter handle to your time on your taskbar.  This is really cool for those of us that present, so that while we demo, you’ll see our twitter handle displayed at all times.

When SQLT is not enough

A SQLT report has all kinds of pertinent information including—to name just a few—optimizer settings, indexes, statistics, plan history, and view definitions. However, sometimes a SQLT report is not enough to solve a SQL performance problem.(read more)

SQL Joinery

Fourth in a series of posts in response to Tim Ford's #EntryLevel Challenge.


SQL supports three types of join operation. Most developers learn the inner join first. But there are two other join operations you should know about. These are the outer join, and the full outer join. These additional join types allow you to write in essence could be termed as optional joins

Inner Joins

The so-called inner-join is the default. It's the happy path from a theory perspective, and it's the join type most SQL developers learn first. Use it to combine related rows from two or more tables. 

For example, perhaps you want to report on all the customers in the AdventureWorks database. You might begin working that business problem by writing the following query:

SQL Joinery

Joins are fundamental in SQL, and are used in most every production query.
There are three types in particular that every developer should fully
understand.



Read the full post at www.gennick.com/database.