webdis server side join - join

Question

First of all excuse me if I got some concept wrong, this a bit new to me. I have to retrieve a number of objects from a webdis server. The way it is being done at the moment is:
Get all the objects ids (serverUrl/ZRANGE/objects_index/-X/-1)
For each object, get attributes (serverUrl/GET/attributeY_objectIdX)
So if I have X objects with Y attributes I have to perform X * Y + 1 REST calls to get all he data, that seems highly inefficient.
From what I understand Multi is the command to perform a join but is not supported by webdis rest api (see Ideas, TODO on webdis page).
Is there a simpler solution that I am missing?
Should I reorganise the way the data is stored?
Can I use websockets to send a MULTI/EXEC command through json:
jsonSocket.send(JSON.stringify(["MULTI", "EXEC", "GET", "etc..."]));

Answer 1

First, instead of having one key per attribute, you should consider use hash objects, so you get one key per object, associated to several properties. The benefit is you can use the HGETALL command to retrieve all the properties of a given object at once. Instead of having X*Y+1 calls, you have only X+1.
Instead of:
SET user:1:name Didier
SET user:1:age 41
SET user:1:country FR
you could have:
HMSET user:1 name Didier age 41 country FR
Then, webdis supports HTTP 1.1 and websocket pipelining, and Redis server supports pipelining using its own protocol. So it should be possible to send several commands to webdis, wait for the results (which will be returned in the same order) while only paying for a single roundtrip.
For instance, the websocket example provided on webdis page actually performs a single roundtrip to execute two commands:
var jsonSocket = new WebSocket("ws://127.0.0.1:7379/.json");
jsonSocket.onopen = function() {
console.log("JSON socket connected!");
jsonSocket.send(JSON.stringify(["SET", "hello", "world"]));
jsonSocket.send(JSON.stringify(["GET", "hello"]));
};
jsonSocket.onmessage = function(messageEvent) {
console.log("JSON received:", messageEvent.data);
};
You could do something similar, and aggregate several HGETALL commands to retrieve the data by batch of n objects.
Please note that with Redis itself (i.e. without webdis), I would probably recommend the same strategy (pipelining HGETALL commands).