package cdb

This is Dustin Sallings OCaml CDB library, pulled from the 2007 wayback machine.

It has been updated to work with OCaml 5.2.0 by Jesse.

What is CDB?

CDB is a simple and elegant constant database. Think of it as an associative array on disk. Reads are fast, but writes are slow because the whole file needs to be rebuilt for every change.

It comes from a time when CPUs were much slower, disks were much smaller, and being clever about how you use resources mattered much more. Today, SQLite and/or JSON are probably better choices in most situations.

Further reading:

1. https://cr.yp.to/cdb/cdb.txt and https://cr.yp.to/cdb.html
2. http://www.cse.yorku.ca/~oz/hash.html
3. https://www.unixuser.org/~euske/doc/cdbinternals/index.html

Getting Started

opam install cdb

Read a value

(* Open the CDB for searching *)
let cdb_file = Cdb.open_cdb_in "my_cdb.cdb" in

(* Get matches for a key *)
let matches = Cdb.get_matches cdb_file "key1" in

(* Iterate over the matches and print them *)
Seq.iter (fun value -> print_endline ("Found value: " ^ value)) matches;

(* Close the CDB file *)
Cdb.close_cdb_in cdb_file

Writing values

(* Create and populate a CDB *)
let creator = Cdb.open_out "my_cdb.cdb" in
Cdb.add creator "key1" "value1";
Cdb.add creator "key2" "value2";
Cdb.close_cdb_out creator;

Contributor

dune build

Test

dune exec ./test/main.exe