fergies-inverted-index

Fergie's Inverted Index

This is my inverted index library. There are many like it, but this one is mine.

Throw JavaScript objects at the index and they will become retrievable by their properties using promises and map-reduce (see examples)

API

Command	Options	Accepts	Returns	Writes	Description
AND	-	properties	ids	no	Boolean AND. Return IDs of objects that have prop.A AND prop.b
DELETE	-	ids	ids	yes	Remove objects from index
DISTINCT	gte, lte	properties	properties	no	Return all properties in a range.
EACH	-	properties	ids	no	For each property provided, get IDs of objects that contain it (use with DISTINCT, MAX and MIN)
GET	gte, lte	properties	ids	no	Get the IDs of objects with a property in the given range
MAX	limit	properties	properties	no	Get the highest property in this namespace
MIN	limit	properties	properties	no	Get the lowest property in this namespace
NOT	-	ids	ids	no	Get all IDs of objects in set A that are not in set B
OBJECT	-	ids	objects	no	Get an object by its ID
OR	-	properties	ids	no	Boolean OR. Return IDs of objects that have either prop.A OR prop.b
PUT	-	objects	ids	yes	Add objects to index
STORE	-	levelup	levelup	both	Get the underlying levelup store.

Getting started

Initialise and populate an index

const fin = require('fergies-inverted-index')

// Make a new index, or open an existing one with this name
fin({ name: 'idx' }).then(idx => {
  idx.PUT([ /* my array of objects */ ]).then(doStuff)
})

Query the index

// (given objects that contain: { land: <land>, colour: <colour>, population: <number> ... })

// get all object IDs where land=SCOTLAND and colour=GREEN
idx.AND('land:SCOTLAND', 'colour:GREEN').then(result)

// as above, but return whole objects
idx.AND('land:SCOTLAND', 'colour:GREEN').then(idx.OBJECT).then(result)

// Get all object IDs where land=SCOTLAND, and those where land=IRELAND
idx.OR('land:SCOTLAND', 'land:IRELAND').then(result)

// queries can be embedded within each other
idx.AND(
  'land:SCOTLAND',
  idx.OR('colour:GREEN', 'colour:BLUE')
).then(result)

// get all object IDs where land=SCOTLAND and colour is NOT GREEN
idx.NOT(
  idx.GET('land:SCOTLAND'),                 // everything in this set
  idx.GET('colour:GREEN', 'colour:RED').    // minus everything in this set
).then(result)

// Get max population
idx.MAX('population').then(result)

(See the tests for more examples.)

Compiling a client-side index that will run in the browser.

Why distribute indexes?