https://github.com/adiwajshing/keyed-db

A light-weight typescript library to manage a sorted & indexed collection with pagination support.
https://github.com/adiwajshing/keyed-db

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A light-weight typescript library to manage a sorted & indexed collection with pagination support.

• Host: GitHub
• URL: https://github.com/adiwajshing/keyed-db
• Owner: adiwajshing
• License: mit
• Created: 2020-07-31T11:49:56.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2023-03-05T11:53:59.000Z (over 1 year ago)
• Last Synced: 2024-03-15T05:07:06.585Z (8 months ago)
• Language: TypeScript
• Homepage:
• Size: 106 KB
• Stars: 34
• Watchers: 5
• Forks: 34
• Open Issues: 6
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Keyed DB

A light-weight node library to manage a sorted & indexed collection with pagination support. 

All done using Binary Search. Based off my swift code for [Queenfisher](https://github.com/adiwajshing/Queenfisher)

## Install

`npm i github:adiwajshing/keyed-db`

## Running Tests

`npm test`

## Functions

``` ts

db = new KeyedDB (t => t.uniqueNumberKeyProperty, t => t.optionalUniqueIDProperty)

// compare with a custom function

db = new KeyedDB ({  

    key: t => t.someProperty,

    compare: (t1, t2) => someComputation(t1, t2) // return -1 if t1 < t2, 0 if t1=t2 & 1 if t1 > t2

}, t => t.optionalUniqueIDProperty)

db.insert (value) // insert value in DB

db.upsert (value) // upserts value

db.insertIfAbsent (value) // only inserts if not already present in DB

db.delete (value) // delete value

db.deleteById (value.optionalUniqueIDProperty) // delete value by referencing the ID

// update the key of a value, 

// will automatically place object after key change

db.updateKey (value, value => value.uniqueKeyProperty = newValue) 

db.paginated (someCursor, 20) // get X results after the given cursor (null for the first X results)

```

## Usage

``` ts

import KeyedDB from '@adiwajshing/keyed-db'

// Let's use the db to sort & maintain a list of chats

// Chats must be accessed quickly via the chatID (the person you're chatting with)

// Chats must be sorted by recency

type Chat = {

    timestamp: Date

    chatID: string

}

// first argument -- sorting property, second argument -- ID property

const db = new KeyedDB(value => value.timestamp.getTime()*-1, value => value.chatID)

for (let i = 0; i < 1000;i++) {

    // insert data

    db.insert (

        {

            timestamp: new Date( new Date().getTime() - Math.random()*10000 ), 

            chatID: `person ${i}`

        }

    )

}

console.log (db.all()) // return internal sorted array

console.log (db.paginated(null, 20)) // return first 20 chats

console.log (db.paginated(null, 20, null, 'before')) // return last 20 chats

console.log (db.paginated(null, 20, chat => chat.chatID.includes('something'))) // return first 20 chats where the chatID contains 'something'

const someDate = new Date().getTime()

const cursorPaginated = db.paginated(someDate, 20)

console.log (cursorPaginated) // return 20 chats after the specified date

db.delete (cursorPaginated[0]) // delete paginated chats 

// update chat timestamp

db.updateKey(cursorPaginated[1], value => value.timestamp = new Date().getTime()) 

```

## Time Complexity

| Operation      | Time Complexity |

|----------------|-----------------|

| db.insert()    | O(logN)         |

| db.delete()    | O(logN)         |

| db.get()       | O(1)            |

| db.updateKey() | O(logN)         |