Setup + Installation

Installing Ruby

brew update
brew install rbenv ruby-build
rbenv install 3.2.2
rbenv global 3.2.2

Add the following to your .zshrc file - use code ~/.zshrc to open in VSCode

eval "$(rbenv init -)"
export PATH="$HOME/.gem/ruby/3.2.0/bin:$PATH"

Then refresh via source ~/.zshrc

Install Bundler if needed

gem install bundler --user-install

Installing RSpec if needed

gem install rspec --user-install

Introduction

Architecture of SQLite:

Features

• Virtual Machine: takes bytecode generated by the front-end as instructions
  • Can perform operations on one or more tables or indexes
  • Basically a big switch statement on the type of bytecode instruction
• Pager: receives commands to read/write pages of data
• Persistence to disk: we can save the database to a file and read it back out again
  • Done via a pager, which asks for page number x, and the pager gives us back a block of memory
  • First, it looks in its cache and on a cache miss, it copies data from disk into memory
  • When the user closes the connection to the db, we flush the cache to disk, close the DB file, and free the memory for Pager/Table data structures
• Cursor: represents a location in the table
• B-Tree: Data structure that represents both tables and indexes
  • Each node corresponds to one page, even if it's not full, so no need to handle for partial pages
  • Order: each node can have up to m children, where m is the tree's "order"

C Trivia

Difference between memcpy() and strncpy()

void *memcpy(void *dest, const void *src, size_t n);

• Copies exactly n bytes, regardless of the data or content.
• Does not stop at null characters ('\0').
• Often used for binary data, structs, or raw memory.
• No null-termination logic.

char *strncpy(char *dest, const char *src, size_t n);

• Copies a null-terminated string with a size limit.
• Copies up to n characters or until a '\0' is encountered in src.
• If src is shorter than n, the rest of dest is padded with '\0'.
• If src is longer than or equal to n, the result is not null-terminated — this is a common gotcha.

Unsigned types

When including #include <stdint.h>, we have:

• uint8_t → unsigned 8-bit integer
• uint16_t → unsigned 16-bit integer
• uint32_t → unsigned 32-bit integer
• uint64_t → unsigned 64-bit integer