count-min-sketch.js

// This example demonstrates the use of the Count-Min Sketch
// in the RedisBloom module (https://redis.io/docs/stack/bloom/)

import { createClient } from 'redis';

const client = createClient();

await client.connect();

// Delete any pre-existing Count-Min Sketch.
await client.del('mycms');

// Initialize a Count-Min Sketch with error rate and probability:
// https://redis.io/commands/cms.initbyprob/
try {
  await client.cms.initByProb('mycms', 0.001, 0.01);
  console.log('Reserved Count Min Sketch.');
} catch (e) {
  console.log('Error, maybe RedisBloom is not installed?:');
  console.log(e);
}

const teamMembers = [
  'leibale',
  'simon',
  'guy',
  'suze',
  'brian',
  'steve',
  'kyleb',
  'kyleo',
  'josefin',
  'alex',
  'nava',
  'lance',
  'rachel',
  'kaitlyn'
];

// Store actual counts for comparison with CMS.
let actualCounts = {};

// Randomly emit a team member and count them with the CMS.
// https://redis.io/commands/cms.incrby/
for (let n = 0; n < 1000; n++) {
  const teamMember = teamMembers[Math.floor(Math.random() * teamMembers.length)];
  await client.cms.incrBy('mycms', {
    item: teamMember,
    incrementBy: 1
  });

  actualCounts[teamMember] = actualCounts[teamMember] ? actualCounts[teamMember] + 1 : 1;

  console.log(`Incremented score for ${teamMember}.`);
}

// Get count estimate for some team members:
// https://redis.io/commands/cms.query/
const [ alexCount, rachelCount ] = await client.cms.query('mycms', [
  'alex',
  'rachel'
]);

console.log(`Count estimate for alex: ${alexCount} (actual ${actualCounts.alex}).`);
console.log(`Count estimate for rachel: ${rachelCount} (actual ${actualCounts.rachel}).`);

// Get overall information about the Count-Min Sketch:
// https://redis.io/commands/cms.info/
const info = await client.cms.info('mycms');
console.log('Count-Min Sketch info:');

// info looks like this:
// { 
//   width: 2000, 
//   depth: 7, 
//   count: 1000 
// }
console.log(info);

await client.quit();