How do I keep first 10 members and delete rest of a Redis sorted set?

Question

I want to keep the result of my last 10 queries in Redis sorted set. I use timestamps as the score. I need to keep top 10 members by score and delete the rest. I basically need ZREMRANGEBYREVSCORE or ZREMRANGEBYREVRANK but these commands do not exist. Is there a way around this?

Answer 1

I find a workaround with using negative scores with zremrangebyrank. I am not sure this is the right way but works for me.

counter = 0;
// temp data
setInterval(async () => {
    counter += 1;
    val = (new Date()).toString() + " " + counter;
    score = -1 * (new Date() / 1000);
    res = await client.zaddAsync("myset", score, val)
}, 1000)

// remove other than top50
setInterval(async () => {
    res = await client.zremrangebyrankAsync("myset", 50, -1);
    console.log("myset zremrangebyrank" + " " + res + " " + val);    
}, 5000)

// log
setInterval(async () => {
    res = await client.zrangeAsync("myset", 0, 5);
    console.log(res);

    res = await client.zcardAsync("myset");
    console.log("myset zcard" + " " + res);      
}, 2000)