The method in Redis to count the various data sizes

If the MySQL database is large, we can easily find out which tables are taking up space. But if Redis has a lot of memory, it's not easy to figure out which keys are taking up the space.

There are some tools that can provide the necessary help, such as redis-rdb-tools, which can directly analyze RDB files to generate reports. Unfortunately, it can't fulfill my requirements 100%, and I don't want to develop on top of it twice. In fact, the development of a dedicated tool is very simple, using SCAN and DEBUG commands, not many lines of code to achieve:

<?php
$patterns = array(

    'foo:.+',

    'bar:.+',

    '.+',

);
$redis = new Redis();

$redis->setOption(Redis::OPT_SCAN, Redis::SCAN_RETRY);
$result = array_fill_keys($patterns, 0);
while ($keys = $redis->scan($it, $match = '*', $count = 1000)) {

    foreach ($keys as $key) {

        foreach ($patterns as $pattern) {

            if (preg_match("/^{$pattern}$/", $key)) {

                if ($v = $redis->debug($key)) {

                    $result[$pattern] += $v['serializedlength'];

                }
                break;

            }

        }

    }

}
var_dump($result);
?>

Of course, if you need to summarize possible key patterns in advance, the simple but less rigorous approach is MONITOR:

shell> /path/to/redis-cli monitor |

       awk -F '"' '$2 ~ "ADD|SET|STORE|PUSH" {print $4}'

Also, it is important to note that because DEBUG returns serializedlength as a serialized length, the final calculated value is less than the actual footprint, but it is still useful to consider the relative size.