Is there MGET analog for Redis hashes?

I'm planning to start using hashes insead of regular keys. But I can't find any information about multi get for hash-keys in Redis wiki. Is this kind of command is supported by Redis?

Thank you.

You can query hashes or any keys in pipeline, i.e. in one request to your redis instance. Actual implementation depends on your client, but with redis-py it'd look like this:

pipe = conn.pipeline()
pipe.hgetall('foo')
pipe.hgetall('bar')
pipe.hgetall('zar')
hash1, hash2, hash3 = pipe.execute()

Client will issue one request with 3 commands. This is the same technique that is used to add multiple values to a set at once.

Read more at http://redis.io/topics/pipelining

If SORT let you use multiple GETs with the -> syntax, and all your hashes had the same fields, you could get them in a bulk reply by putting their names into a set and sorting that.

  SORT names_of_hashes GET *->field1 *->field2 *->field3 *->etc

But it doesn't look like you can do that with the hash access. Plus you'd have to turn the return list back into hashes yourself.

UPDATE: Redis seems to let you fetch multiple fields if you name your hashes nicely:

redis> hset hash:1 name fish
(integer) 1
redis> hset hash:2 name donkey
(integer) 1
redis> hset hash:3 name horse
(integer) 1
redis> hset hash:1 type fish
(integer) 1
redis> hset hash:2 type mammal
(integer) 1
redis> hset hash:3 type mammal
(integer) 1
redis> sadd animals 1
(integer) 1
redis> sadd animals 2
(integer) 1
redis> sadd animals 3
(integer) 1
redis> sort animals get # get hash:*->name get hash:*->type
1. "1"
2. "fish"
3. "fish"
4. "2"
5. "donkey"
6. "mammal"
7. "3"
8. "horse"
9. "mammal"

No MHGETALL but you can Lua it:

local r = {}
for _, v in pairs(KEYS) do
  r[#r+1] = redis.call('HGETALL', v)
end

return r

Redis has a HMGET command, which returns the values of several hash keys with one command.

There is no command to do it on one shot, but there is a way to do it "nicely", using a list (or sorted set) where you would store you hashKeys, and then retrieve them as bulk using multi.

In PHP:

$redis->zAdd("myHashzSet", 1, "myHashKey:1");
$redis->zAdd("myHashzSet", 2, "myHashKey:2");
$redis->zAdd("myHashzSet", 3, "myHashKey:3");

$members = $redis->zRange("myHashzSet", 0, -1);
$redis->multi();
foreach($members as $hashKey) {
    $redis->hGetAll($hashKey);
}
$results = $redis->exec();

  

I recommand using a sorted set, where you use the score as an ID for your hash, it allows to take advantages of all score based command.