Clean Architecture

Video

Not too much detail too early.

A good architecture allows major decisions to be DEFERRED!

A good architecture maximizes the number of decisions NOT made.

You only test the parts of the application that you want to work.

Things hard to test:

1. Anything at outer boundary of the system, like GUI
2. It’s very difficult to test things if you don’t know the answer

Top 10 SQL Performance Tips & Tricks for Java Developers

Video Slide

Round trips

• Avoid unnecessary round trips to the database
• Every round trip includes time that you spend on the network
• That does not mean to avoid processing anything at the database

Auto commit

• The driver commits every DML on your behalf, implicitly
• That is, for every single insert, update, delete, merge will be a commit
• Implies a second round trip to the databases for every DML operation
• Forces database to write to disk
• You can never rollback your changes
• It’s default to turn on, turn off it

Bulk processing

• Database work best with set based process
• Process as much as possible on the side where it makes most sense
• Generally, a single SQL statement execution is the fastest
• Avoids unnecessary round trips

Bind variables

• A bind variable allows you to bind data to an explicit data type
  • Without having to convert the data type form string
  • Without having to parse the SQL statement again
• Avoids SQL injections

Fetch size

• Drive fetches more than on row from the database at once
• Avoids unnecessary round trips

Save point

KISS (Keep it simple SQL)

• Easier to maintain
• Faster to optimize
• Less likely for the optimizer to get it wrong

Parallel queries

SELECT /*+ PARALLEL */ id, create_date, first_name...

Explain plans

SQL wait events (Oracle only)