https://github.com/opencoff/go-cdb

DJB's Constant DB - with changes to add sha256 checksum to the generated DB
https://github.com/opencoff/go-cdb

Last synced: 10 months ago
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DJB's Constant DB - with changes to add sha256 checksum to the generated DB

• Host: GitHub
• URL: https://github.com/opencoff/go-cdb
• Owner: opencoff
• License: mit
• Created: 2018-02-28T21:53:11.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2018-02-28T22:09:21.000Z (over 8 years ago)
• Last Synced: 2025-04-01T11:08:57.775Z (about 1 year ago)
• Language: Go
• Size: 8.79 KB
• Stars: 4
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
CDB

===

[![GoDoc](https://godoc.org/github.com/colinmarc/cdb/web?status.svg)](https://godoc.org/github.com/colinmarc/cdb) [![build](https://travis-ci.org/colinmarc/cdb.svg?branch=master)](https://travis-ci.org/colinmarc/hdfs)

This is a native Go implementation of [cdb][1], a constant key/value database

with some very nice properties. From the [design doc][1]:

> cdb is a fast, reliable, simple package for creating and reading constant databases. Its database structure provides several features:

> - Fast lookups: A successful lookup in a large database normally takes just two disk accesses. An unsuccessful lookup takes only one.

> - Low overhead: A database uses 2048 bytes, plus 24 bytes per record, plus the space for keys and data.

> - No random limits: cdb can handle any database up to 4 gigabytes. There are no other restrictions; records don't even have to fit into memory. Databases are stored in a machine-independent format.

This version is modified by Sudhi Herle:

- addition of a SHA256 checksum over the entire CDB (appended to end

  of file) and verified when opened

- uses Zi Long Tan's superfast hash

[1]: http://cr.yp.to/cdb.html

Usage

-----

```go

writer, err := cdb.Create("/tmp/example.cdb")

if err != nil {

  log.Fatal(err)

}

// Write some key/value pairs to the database.

writer.Put([]byte("Alice"), []byte("Practice"))

writer.Put([]byte("Bob"), []byte("Hope"))

writer.Put([]byte("Charlie"), []byte("Horse"))

// Freeze the database, and open it for reads.

db, err := writer.Freeze()

if err != nil {

  log.Fatal(err)

}

// Fetch a value.

v, err := db.Get([]byte("Alice"))

if err != nil {

  log.Fatal(err)

}

log.Println(string(v))

// => Practice

// Iterate over the database

iter := db.Iter()

for iter.Next() {

    log.Printf("The key %s has a value of length %d\n", string(iter.Key()), len(iter.Value()))

}

if err := iter.Err(); err != nil {

    log.Fatal(err)

}

```