StackExchange.Redis SetAdd（key，val）崩溃，键= GUID

Question

Very annoying crash with StackExchange.Redis SetAdd(key, val) .

I want to set a set with the programs GUID as a key.

I found (after 3 hours debugging) that SetAdd(key, val) works with some GUID, but crashes with others:

        string key = "02639d71-0935-35e8-9d1b-9dd1a2a34629";
        const string val = "somevalue";

        db.SetAdd(key, val); // <=== Works

        key = "02639d71-0935-35e8-9d1b-9dd1a2a34627";
        db.SetAdd(key, val); // <=== CRASH @@!!@!@!

The difference is the last character "9" vs "7"

Doesn't SetAdd work with the local GUID as a Key?

Environment: C# .NET 4 Win 8.1 VS2013

Crash message:

An unhandled exception of type 'StackExchange.Redis.RedisServerException' occurred in StackExchange.Redis.dll
Additional information: WRONGTYPE Operation against a key holding the wrong kind of value

The crash point in StackExchange.Redis

...

I tested this Code in LINQPad. It crashes on the same place. The first GUID works, the second doesn't.

It seams that the crash is not due to this is the starting app GUID.

More test with different GUIDs. Only that ending with '7' crashes.

    key = "02639d71-0935-35e8-9d1b-9dd1a2a34622";
    key = "02639d71-0935-35e8-9d1b-9dd1a2a34623";
    key = "02639d71-0935-35e8-9d1b-9dd1a2a34624";
    key = "02639d71-0935-35e8-9d1b-9dd1a2a34625";
    key = "02639d71-0935-35e8-9d1b-9dd1a2a34626";
    key = "02639d71-0935-35e8-9d1b-9dd1a2a34627"; // <= crashes
    key = "02639d71-0935-35e8-9d1b-9dd1a2a34628";
    key = "02639d71-0935-35e8-9d1b-9dd1a2a34629";

...

KeyExists , StringIncrement , StringSet work well with key = my GUID.

Answer 1

Redis keys are opaque. That message:

WRONGTYPE Operation against a key holding the wrong kind of value

simply means that you have previously stored data in that key of a type that isn't a "set". Try (in redis-cli):

TYPE "02639d71-0935-35e8-9d1b-9dd1a2a34627"

which will tell you the data type of the existing data. You can only use SADD if either the key does not exist, or if it exists and is a set .