{Ask HN}What's the largest amount of bad code you have ever seen work?


Oracle Database 12.2.

It is close to 25 million lines of C code.

What an unimaginable horror! You can't change a single line of code in the product without breaking 1000s of existing tests. Generations of programmers have worked on that code under difficult deadlines and filled the code with all kinds of crap.

Very complex pieces of logic, memory management, context switching, etc. are all held together with thousands of flags. The whole code is ridden with mysterious macros that one cannot decipher without picking a notebook and expanding relevant pats of the macros by hand. It can take a day to two days to really understand what a macro does.

Sometimes one needs to understand the values and the effects of 20 different flag to predict how the code would behave in different situations. Sometimes 100s too! I am not exaggerating.

The only reason why this product is still surviving and still works is due to literally millions of tests!

Here is how the life of an Oracle Database developer is:

The above is a non-exaggerated description of the life of a programmer in Oracle fixing a bug. Now imagine what horror it is going to be to develop a new feature. It takes 6 months to a year (sometimes two years!) to develop a single small feature (say something like adding a new mode of authentication like support for AD authentication).

The fact that this product even works is nothing short of a miracle!

I don't work for Oracle anymore. Will never work for Oracle again!