Count and Sum size per keys prefix of Redis instance

size_prefix.js

/*
How to use:
# 1. install bun
curl -fsSL https://bun.sh/install | bash
# 2. bun install ioredis
# 3. customize the connection string below
# 4. run this script
bun size_prefix.js prefixToScan
*/
import Redis from 'ioredis'
const redisClient = new Redis({
  port: 6379, // Redis port
  host: "127.0.0.1", // Redis host
  //username: "default", // needs Redis >= 6
  //password: "xxyyzz",
  //db: 0, // Defaults to 0
})
async function calculateKeysSize(redisClient, matchPattern) {
          let iterations = 0;
          let totalKeys = 0;
          let totalBytes = 0;
          let nextCursor, currCursorKeys;
          while (nextCursor !== "0") {
                      [nextCursor, currCursorKeys] = await redisClient.scan(nextCursor || 0, "match", matchPattern);

                      totalKeys += currCursorKeys.length;

                      const pipeline = redisClient.pipeline();
                      for (const currKey of currCursorKeys) {
                                    pipeline.memory("usage", currKey);
                                  }
                      const responses = await pipeline.exec();
                      const sizes = responses.map((response) => response[1]);
                      totalBytes += sizes.reduce((a, b) => a + b, 0);

                      if (iterations % 1000 == 0) console.log(`scanned ${totalKeys} so far.. total size: ${totalBytes} Bytes, iter/cursor: ${iterations}/${nextCursor}`);
                      iterations++;
          }

          return { totalKeys, totalBytes };
}

console.log('scanning prefix', Bun.argv[2])
let x = await calculateKeysSize(redisClient, Bun.argv[2]+"*");
console.log(x)