- Postgres – SELECT, WHERE and ORDER BY
The query you write a hundred times a day, done carefully. Filtering with AND/OR and the parenthesis that changes the answer, LIKE versus ILIKE, IN and BETWEEN, ordering with NULLS LAST, DISTINCT versus DISTINCT ON, and keyset pagination — because OFFSET 10000 reads ten thousand rows to throw them away. Plus the three ways NULL will surprise you.
- Postgres – Tables, Keys and Constraints
CREATE TABLE, then the constraints that make wrong data impossible instead of unlikely. Identity columns rather than serial, primary and foreign keys and what ON DELETE actually chooses, UNIQUE, NOT NULL, CHECK — and the exclusion constraint that stops two guests booking the same property on the same night, enforced by the database rather than by hoping the application checked.
- Javascript Module
JavaScript programs start off pretty small almost every time. Not until your project grows and grows so large that your scripts may start to look like spaghetti code. At this point, your code has to be broken down into separate modules that can be imported where needed. The good news is that modern…
- Algorithm interview – Big O
Big O is about how long an algorithm takes to run from start to end and how well it scales based on the size of the input or dataset. Big O is mostly measured based on the worst-case scenario even though some algorithms might finish early based on some logic. Here is another graph […]
- Postgres – Data Types
The choices you cannot cheaply undo later. `text` versus `varchar(n)` and why the length limit buys nothing, `numeric` for money and never a float, `timestamptz` versus `timestamp` and what actually gets stored, `uuid` alongside an integer key rather than instead of it, arrays, and why StayHub stores its enums as varchar. With a mapping table to Python and Java types.