Key-value data base

Description

This program is utility for work with key-value database

User guide

Run

• You can run this utility with this command:

./gradlew --console=plain -q run

Database file format

We consider that database is a directory with name ends with .db. Inside this directory we have the file with name size were we store database size and the list of file. Each file name is equal to hash of keys stored in it.

List of commands:

• help show help message
• quit - finish work with databases and quit this manager
• create [NAME] - create database with name equals to NAME
• open [NAME] - open and work with database NAME
• delDB - delete opened database
• fetch [KEY] - fetch the value of given KEY from opened database
• delete [KEY] - delete given KEY from opened database
• store [KEY] [VALUE] - store pair (KEY, VALUE) into opened database

Example of using

KVDB> create a
a.db> create b
b.db> open a
a.db> delDB
KVDB> open b
b.db> store key value
b.db> store "key with spaces" "value with spaces"
b.db> fetch "key with spaces"
value with spaces
b.db> store "key" "value with \" special symbols \\ "
b.db> fetch key 
value with " special symbols \ 
b.db> delete key
b.db> fetch key
No item "key" in database
b.db> delDB
KVDB> quit

Testing

This utility was tested with test in file src/test/kotlin/TestBigDataBase.kt So, it did 10^5 Sequentially store operations, then 10^5 fetch operations, then 10^5 delete operations for 3 minutes and 10 seconds (On HDD)