ChromoDB is a disk based key-value store. It provides operations like inserting, updating, retrieving, and deleting key-value pairs. The database is designed to efficiently handle read and write operations. ChromoDB combines aspects of both a hash map (for indexing) and a linked list (for storing data records), resulting in a file-based key-value store.

If using networked configuration the default port is 7676 on TCP OR TLS can be changed with --port flag.

How to use

Use like embedded DB

>./chromodb

>db>DISK
..

Limit memory on start up

./chromodb --memory-limit=7500 * 1024 * 1024

Networked

./chromodb --shell=false --user=alex --pass=somepassword

Test with NC

base64 encode:
alex\0somepassword

YWxleFwwc29tZXBhc3N3b3Jk

Make sure to have ChromoDB started(networked of course)

nc localhost 7676

~/chromodb$ nc localhost 7676
YWxleFwwc29tZXBhc3N3b3Jk
db>put->some key->some value
db>get->some key

TLS

./chromodb --shell=false --user=alex --pass=somepassword --tls=true --key="key.pem" --cert="cert.pem"

Structure

The database implementation is organized into a many Go packages with the following main components:

DataStructure

• DataStructure The central struct representing the database. It includes fields for data and index file handles, as well as the next available offset for storing new data records.

• DataStructure.OpenDB A function to open or create a new FractalTree instance. It takes the filenames for the data and index files and returns a FractalTree object.

• DataStructure.Close A method to close the FractalTree database, ensuring proper cleanup and closing of file handles.

• DataStructure.Put A method to insert or update a key-value pair in the database.

• DataStructure.Get A method to retrieve the value associated with a given key.

• DataStructure.Update A method to update the value associated with a given key.

• DataStructure.Delete A method to delete a key-value pair from the database.

System

• System.MonitorMemory Monitors current memory use
• System.ExecuteCommand Executes a command
• System.QueryParser Parses database queries
• System.StartTCPTLSListener Starts TCP/TLS listener
• System.getDiskSpace Gets current database disk usage
• System.Stop Stops TCP/TLS listener gracefully
• System.StartTransaction Starts DB transaction
• System.CommitTransaction Commits DB transaction
• System.RollbackTransaction Rolls back DB transaction

File Storage

The database stores its data in two separate files:

• Data File Contains the actual key-value pairs and their associated metadata.
• Index File Maintains an index of keys along with their corresponding offsets in the data file.

Key-Value Storage Format

The key-value pairs are stored in the data file using the following format:

• Key Length 4 bytes (uint32) - Length of the key in bytes.
• Value Length 4 bytes (uint32) - Length of the value in bytes.
• Key Variable-length byte array - The actual key data.
• Value Variable-length byte array - The actual value data.
• Offset 8 bytes (int64) - Offset of the next record in the data file.

Query Parser

Additionally, a queryparser package is provided to interact with the database using simple queries. The QueryParser function accepts a query in the form of a byte slice and performs the corresponding database operation based on the query type (PUT, GET, DEL).

Commands/Queries

GET

GET->keyname

PUT

PUT->keyname->value

Key names and values can be of any type. We store them as a byte array.

If you want to update you just run the put with a different value

PUT->keyname->2

DEL

DEL->keyname

MEM

MEM

Shows current database memory usage.

DISK

DISK

Shows current database disk usage

Limitations

• keys cannot have spaces