John Watson's blog

Upgrading to 12.2 ? Make sure you won't break JSON

articles: 

Will upgrade from 12.1 to 12.2 break your applications? It may if your developers are using JSON.

Tuning with equivalent SQLs - a little challenge

articles: 

I am fascinated by what I call "equal SQL": statements that are equivalent, in that they deliver the same result but may have hugely different performance characteristics. Here's a little case study.

Compression test, 12cR2

articles: 

Just how effective is Hybrid Columnar Compression? This test shows that HCC is impressive, but that thought needs to be put into choice of compression algorithm.

12cR2 lots of new instance parameters

articles: 

Comparing database 12cR1 release 12.1.0.2 to 12cR2 release 12.2.0.0.3, I see these new parameters:

12cR2 new feature: online table move

articles: 

Move a table without locks and without breaking indexes. That's pretty cool.

Is row-by-row processing really slow-by-slow? Emphatically: YES

articles: 

Developers who come to Oracle with a background in procedural languages sometimes do not understand how efficient SQL's set oriented processing can be. This little demonstration should convince them: never use PL/SQL when SQL will do.

How to change column order when using SELECT *

articles: 

We all know that using SELECT * is bad programming. One reason is that you cannot control the order in which columns are returned. Well, you can in release 12c.

Oracle 12cR2 - the next release, cloud only?

articles: 

We are all waiting for database release 12.2 - but you won't get it on your own hardware.

How indexes can degrade performance

articles: 

Indexes may improve the performance of SELECT statements, but what about DML? This simple demo shows how bad they can be.

Roles , PL/SQL, and ORA-00942: table or view does not exist

articles: 

Many developers find that their code fails with ORA-942, but when they test the failing statement from the SQL> prompt, it works. Why, and what can you do to fix it?

Pages

Subscribe to RSS - John Watson's blog