x0st/xstdb

A small database written in Java (WIP).

What the heck?

Just a domestic database written in Java (WIP).

Supported queries

Create a table

Syntax:

add %table_name% %columns_definition%

Samples:

• add my_table [id INTEGER] [my_col STRING]
• add anotherone [id INTEGER] [my_col STRING] [col STRING] [my STRING]
• add table [id INTEGER]

Show table's info

Syntax:

show %table_name%

Samples:

• show my_table

Insert a record

Syntax:

put %table_name% %column_list% %data%

Samples:

• put my_table [id my_col another_col] [25 somestring "some string"]
• put my_table [id] [25]
• put users [name] ["David"]
• put users [name] [David]

Select records

Syntax:

get %table_name%

get %table_name% %conditions% where %placeholders%

Samples:

• get my_table
• get users [id = :id] where [:id = 1]
• get customers [age > :age & city = :city] where [:age = 20 & :city = London]
• get users [id > :id | name = :name] where [:name = "John" & :id = 50]

Delete records

Syntax:

delete %table_name%

delete %table_name% %conditions% where %placeholders%

Samples:

• delete my_table
• delete users [id = :id] where [:id = 1]
• delete customers [age > :age & city = :city] where [:age = 20 & :city = London]
• delete users [id > :id | name = :name] where [:name = "John" & :id = 50]

How data is stored

xstdb utilizes two files to store data: %table%.dat and %table%.def. The first one contains records, the latter - table's definition.

%table%.def's structure

purpose	type	bytes taken
table definition (file size)	SHORT INT	2 bytes
rows count	INTEGER	4 bytes
table name's length	INTEGER	4 bytes
table name	STRING	? bytes
number of columns	BYTE	1 byte
column 1: name's length	INTEGER	4 bytes
column 1: name	STRING	? bytes
column 1: type	BYTE	1 byte
column 1: size	INTEGER	4 bytes
column 2: name's length	INTEGER	4 bytes
column 2: name	STRING	? bytes
column 2: type	BYTE	1 byte
column 2: size	INTEGER	4 bytes
................	........	.......