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minisql

MiniSQL is a research project aimed at implementing a simple relational database in Golang. This project exists mostly for myself as a way to learn principles and design of relational databases. It is not meant to be used as a real database.

Shout out to some great repos and other resources that were invaluable while figuring out how to get this all working together:

Run minisql in your command line:

go run cmd/minisql/main.go
minisql>

Current Features

I plan to implement more features of traditional relational databases in the future as part of this project simply to learn and discovery how various features I have grown acustomed to over the years are implemented under the hood. However, currently only a very small number of features are implemented:

  • simple SQL parser (partial support for CREATE TABLE, INSERT, SELECT, UPDATE queries)
  • only tables supported, no indexes (this means all selects are scanning whole tables for now)
  • only int4, int8 and varchar columns supported
  • no primary key support (tables internally use row ID as key in B tree data structure)
  • no joins
  • only simple WHERE conditions with AND and OR, no support for more complex nested conditions using parenthesis
  • no transaction support
  • no page overflow support, entire rows must fit within a 4096 byte page

Planned features:

  • support additional basic query types such as DELETE, DROP TABLE
  • support NULL values
  • B+ tree and support indexes (starting with unique and primary)
  • more column types starting with simpler ones such as bool and timestamp
  • support bigger column types such as text that can overflow to more pages via linked list data structure
  • joins such as INNER, LEFT, RIGHT
  • support ORDER BY, LIMIT, GROUP BY
  • dedicate first 100B of root page for config similar to how sqlite does it
  • support altering tables
  • transactions
  • vacuuming
  • benchmarks

Meta Commands

You can use meta commands, type .help to see available commands or .exit to quit minisql:

minisql> .help
.help    - Show available commands
.exit    - Closes program
.tables  - List all tables in the current database

Examples

Create a table:

minisql> create table foo(id int4, email varchar(255), age int4)
Rows affected: 0
minisql>

Insert a row:

minisql> insert into foo(id, email, age) values(1, '[email protected]', 35)
Rows affected: 1
minisql>

Insert multiple rows:

minisql> insert into foo(id, email, age) values(2, '[email protected]', 32), (3, '[email protected]', 27)
Rows affected: 2
minisql>

Insert more than a single page worth of data:

minisql> insert into foo(id, email, age) values(1, '[email protected]', 35), (2, '[email protected]', 32), (3, '[email protected]', 27), (4, '[email protected]', 32), (5, '[email protected]', 27), (6, '[email protected]', 32), (7, '[email protected]', 27),  (8, '[email protected]', 32), (9, '[email protected]', 27),  (10, '[email protected]', 32), (11, '[email protected]', 27),  (12, '[email protected]', 32), (13, '[email protected]', 27), (14, '[email protected]', 27), (15, '[email protected]', 27)
Rows affected: 15
minisql>

Select from table:

minisql> select * from foo
 id                   | email                                    | age
----------------------+------------------------------------------+----------------------
 1                    | [email protected]                         | 35
 2                    | [email protected]                         | 32
 3                    | [email protected]                         | 27
minisql>

Update rows:

minisql> update foo set id = 45 where id = 75
Rows affected: 0
minisql>