trying to understand how DB -simple one- were implemented, so let's build one ...

note: i'm following the Connor Stack aka cstack tutorial for building his own DB

repo link -> https://github.com/cstack/db_tutorial?tab=readme-ov-file

the link of tutorial -> https://cstack.github.io/db_tutorial/

-- part1 ->

• The SQLite architecture consists of several components: SQL compiler (front-end), VM, backend (B-tree, pager, and OS interface).
• Each component does some work and passes it to the next layer.
• The input to the front-end is a SQL query. The output is SQLite virtual machine bytecode.
• It starts a read-execute-print loop, which takes an input buffer (an array of characters in the end), the length of that buffer, and the length of incoming input.
• The first command is ".exit", which terminates the program.

-- part2 ->

• We start by making an SQL compiler that parses a string and outputs an internal representation called bytecode.
• Instead of comparing commands like ".exit", we separate the commands into two types: one for meta commands and the other for insertion, selection, etc.
• If the command starts with ".", it's a meta command; otherwise, we switch for insertion or selection. If the statement is correct, return the state of success for this statement; otherwise, return unrecognized.
• In the end, compilation is about filtering the commands and checking if they're typed correctly or not.

-- part3 ->

this part was generally about how to parse the insert query, save it in a table and retrive it with select statement

• to parse insert query he used sscanf to read formatted input and asign the data to row struct
• row struct was basically the hard-coded row containt for our table
• to save data in memory we used array for simplicitly and its size is the max number for table to have pages
• a page is fixed-size that is contiguous block of memory that contains the data of 1 row
• To save data in memory, a Row structure is converted into a binary format suitable for storage or transmission in the insert statement. Conversely, binary data is converted back into a Row structure, restoring its original state in the select statement.