node-constant-db

A cdb implementation in node.js, supporting both read and write capabilities.

Installation

npm install constant-db

Changes from v1.0.0

• Renamed getRecord() to get()
• Renamed putRecord() to put()
• Added getNext()
• Dropped promise support
• Completely rewritten! get() calls should be much faster.

Example

Writable cdb:

var writable = require('constant-db').writable;

var writer = new writable('./cdbfile');
writer.open(function cdbOpened(err) {
    writer.put('meow', 'hello world');
    writer.close(function cdbClosed(err) {
        console.log('hooray!');
    });
});

Readable cdb:

var readable = require('constant-db').readable;

var reader = new readable('./cdbfile');
reader.open(function cdbOpened(err) {
    reader.get('meow', function gotRecord(err, data) {
        console.log(data); // results in 'hello world!'
        
        reader.close(function cdbClosed(err) {
            console.log('awesome!');
        });
    });
});

Documentation

Readable cdb

To create a new readable instance: new require('constant-db').readable(file);

open(callback(err, cdb))

Opens the file for reading, and immediately caches the header table for the cdb (2048 bytes).

get(key, [offset], callback(err, data))

Attempts to find the specified key, and calls the callback with an error (if not found) or the data for that key (if found). If an offset is specified, the cdb will return data for the nth record matching that key.

getNext(callback(err, data))

Continues the previous get() call, finding the next record under the key get() was called with. This should be slightly faster than calling get() with an offset.

close(callback(err, cdb))

Closes the file. No more records can be read after closing.

Writable cdb

To create a new writable instance: new require('constant-cdb').writable(file);

open(callback(err, cdb))

Opens the file for writing. This will overwrite any file that currently exists, or create a new one if necessary.

put(key, data)

Writes a record to the cdb.

close(callback(err, cdb))

Finalizes the cdb and closes the file. Calling close() is necessary to write out the header and subtables required for the cdb!

Benchmark

node benchmarks/cdb-random-benchmark.js