Broadcast commands in the Cluster client

[uglide]

Motivation

The Cluster client should provide overrides for specific Redis Core and module commands to make them easy to use with OS Cluster API.

• Provide an abstraction that handles FT.AGGREGATE and executes FT.CURSOR READ or FT.CURSOR DEL on the correct node (on the node where FT.AGGREGATE was executed) automatically
• Commands that should be executed on primaries with Round-robin load balancing/scheduling
  • FT.SEARCH
  • FT.AGGREGATE
  • TS.MGET
  • TS.MRANGE
• Commands that should be broadcasted to all primaries
  • CONFIG SET
  • FLUSHALL
  • FLUSHDB
  • FUNCTION DELETE
  • FUNCTION FLUSH
  • FUNCTION KILL
  • FUNCTION RESTORE
  • SCRIPT FLUSH
  • SCRIPT KILL
  • SLOWLOG RESET
  • FT.ALIASADD
  • FT.ALIASDEL
  • FT.ALIASUPDATE
  • FT.ALTER
  • FT.CREATE
  • FT.DROPINDEX
• JSON.MGET:

import { createCluster } from 'redis';

const cluster = createCluster({
    rootNodes: [
        // ...
    ]
});

cluster.on('error', (err) => console.log('Redis Cluster Error', err));

await cluster.connect();

await cluster.json.set('doc1', '$', {
    name: 'Alice',
    age: 32,
    coins: 100,
    email: 'alice@nonexist.com'
})

await cluster.json.set('doc2', '$', {
    name: 'Bob',
    age: 23,
    coins: 15,
    email: 'bob@somewhere.gov'
})

// Both mget commands should return all documents from cluster
console.log(await cluster.json.mGet(['doc1', 'doc2'], '$..name'))
console.log(await cluster.json.mGet(['doc2', 'doc1'], '$..name'))

Basic Code Example

No response

[leibale]

https://github.com/redis/node-redis/blob/master/docs/clustering.md#command-routing

[uglide]

@leibale JSON.MGET is a different beast compared to MGET. We don't know the key of documents where the path return us any results. That's why it's helpful to have a high-level wrapper that merges results from all primaries.

[leibale]

Then we need a wrapper like in Graph... executing client.ft.search (or any other command) should be as close as possible to the redis-cli version (with some "type mapping"). "Automagically" running multiple commands when the user executed only one feels wrong.

@chayim @itamarhaber @guyroyse @simonprickett WDUT?

[itamarhaber]

Idk about the implementation, but I'm just saying that where a command should run is a part of the command's docs and modules should use the same API: https://redis.io/docs/reference/command-tips/#request_policy

[leibale]

so something like

const REQUEST_POLICIES = {
  ...
};

const RESPONSE_POLICES = {
  ...
};

// will default to the policy defined in redis
cluster.ping();

// can be overridden
cluster.withPolicy({
  request: ...,
  response: ...
}).ping();