Bucket Types

Bucket types allow groups of buckets to share configuration details and for Riak users to manage bucket properties more efficiently than in the older configuration system based on bucket properties.

Important note on cluster downgrades
If you upgrade a Riak to version 2.0 or later, you can still downgrade the cluster to a pre-2.0 version as long as you have not created and activated a bucket type in the cluster. Once any bucket type has been created and activated, you can no longer downgrade the cluster to a pre-2.0 version.

How Bucket Types Work

The older configuration system, based on bucket properties, involves setting bucket properties for specific buckets either through HTTP or Protocol Buffers. With this approach, you can take any given bucket and modify a wide range of properties, from n_val to allow_mult and far beyond.

Using bucket types also involves dealing with bucket properties, but with a few crucial differences:

  • Bucket types enable you to create bucket configurations and assign those configurations to as many buckets as you wish, whereas the previous system required configuration to be set on a per-bucket basis
  • Nearly all bucket properties can be updated using bucket types, except the datatype and consistent properties, related to Riak data types, and strong consistency respectively
  • Bucket types are more performant than bucket properties because divergence from Riak’s defaults doesn’t have to be gossiped around the cluster for every bucket, which means less computational overhead

It is important to note that buckets are not assigned types in the same way that they are configured when using bucket properties. You cannot simply take a bucket my_bucket and assign it a type the way that you would, say, set allow_mult to false or n_val to 5, because there is no type parameter contained within the bucket’s properties (i.e. props).

Instead, bucket types are applied to buckets on the basis of how those buckets are queried. Queries involving bucket types take the following form:

GET/PUT/DELETE /types/<type>/buckets/<bucket>/keys/<key>

In the older system, only bucket and key are specified in queries:

GET/PUT/DELETE /buckets/<bucket>/keys/<key>

When to Use Bucket Types

In many respects, bucket types are a major improvement over the older system of bucket configuration, including the following:

  • Bucket types are more flexible because they enable you to define a bucket configuration and then change it if you need to.
  • Bucket types are more reliable because the buckets that bear a given type only have their properties changed when the type is changed. Previously, it was possible to change the properties of a bucket only through client requests.
  • Whereas bucket properties can only be altered by clients interacting with Riak, bucket types are more of an operational concept. The riak-admin bucket-type interface (discussed in depth below) enables you to manage bucket configurations on the operations side, without recourse to Riak clients.

For these reasons, we recommend always using bucket types in versions of Riak 2.0 and later.

Managing Bucket Types Through the Command Line

Bucket types are created, updated, activated, and more through the riak-admin bucket-type interface.

Below is a full list of available sub-commands:

Command Action Form
create Create or modify a bucket type before activation create <type> <json>
activate Activate a bucket type activate <type>
list List all currently available bucket types and their activation status list
status Display the status and properties of a specific bucket type status <type>
update Update a bucket type after activation update <type> <json>

Creating a Bucket Type

Creating new bucket types involves using the create <type> <json> command, where <type> is the name of the type and <json> is a JSON object of the following form:

{
  "props": {
    "prop1": "val1",
    "prop2": "val2",
    ...
  }
}

Getting started with Riak clients

If you are connecting to Riak using one of Basho’s official client libraries, you can find more information about getting started with your client in our Developing with Riak KV: Getting Started section.

If creation is successful, you should see the following output:

type_using_defaults created
The `create` command can be run multiple times prior to a bucket type being activated. Riak will persist only those properties contained in the final call of the command.

Creating bucket types that assign properties always involves passing stringified JSON to the create command. One way to do that is to pass a JSON string directly. The following creates a bucket type n_equals_1, which sets n_val to 1:

riak-admin bucket-type create n_equals_1 '{"props":{"n_val":1}}'

If you wish, you can also pass in a JSON string through a file, such as a .json file:

riak-admin bucket-type create from_json_file '`cat props.json`'

Like all bucket types, this type needs to be activated to be usable within the cluster.

Activating a Bucket Type

Activating a bucket type involves the activate command from the same bucket-type interface used before:

riak-admin bucket-type activate my_bucket_type

When activation has succeeded, you should see the following output:

my_bucket_type has been activated

A bucket type can be activated only when the type has been propagated to all running nodes. You can check on the type’s readiness by running riak-admin bucket-type status <type_name>. The first line of output will indicate whether or not the type is ready.

In a stable cluster, bucket types should propagate very quickly. If, however, a cluster is experiencing network partitions or other issues, you will need to resolve those issues before bucket types can be activated.

Listing Bucket Types

You can list currently available bucket types using the list command:

riak-admin bucket-type list

This will return a simple list of types along with their current status (either active or not active). Here is an example console output:

riak-admin bucket-type list

An example response:

type1 (active)
type2 (not active)
type3 (active)

Checking a Type’s Status

You can check on the status—i.e. the configuration details—of a bucket type using the status <type> command:

riak-admin bucket-type status my_bucket_type

The console will output two things if the type exists:

  1. Whether or not the type is active
  2. The bucket properties associated with the type

If you check the status of a currently active type called my_bucket_type that simply bears a default bucket configuration, the output will be as follows:

my_bucket_type is active

active: true
allow_mult: true

... other properties ...

w: quorum
young_vclock:20

Updating a Bucket Type

The bucket-type update command functions much like the bucket-type create command. It simply involves specifying the name of the bucket type that you wish to modify and a JSON object containing the properties of the type:

riak-admin bucket-type update type_to_update '{"props":{ ... }}'

Note

Any bucket properties associated with a type can be modified after a bucket is created, with two important exceptions: consistent and datatype. If a bucket type entails strong consistency (requiring that consistent be set to true) or is set up as a map, set, or counter, then this will be true of the bucket type once and for all.

If you need to change one of these properties, it is recommended that you simply create and activate a new bucket type.

Buckets as Namespaces

In versions of Riak prior to 2.0, all queries are made to a bucket/key pair, as in the following example read request:

Location myKey = new Location(new Namespace("my_bucket"), "my_key");
FetchValue fetch = new FetchValue.Builder(myKey).build();
client.execute(fetch);
bucket = client.bucket('my_bucket')
bucket.get('my_key')
$location = new Location('my_key', new Bucket('my_bucket'));
(new \Basho\Riak\Command\Builder\FetchObject($riak))
  ->atLocation($location)
  ->build()
  ->execute();
bucket = client.bucket('my_bucket')
bucket.get('my_key')
var id = new RiakObjectId("my_bucket", "my_key");
client.Get(id);
client.fetchValue({ bucket: 'my_bucket', key: 'my_key' }, function (err, rslt) {
});
{ok, Object} = riakc_pb_socket:get(Pid,
                                   <<"my_bucket">>,
                                   <<"my_key">>).
curl http://localhost:8098/buckets/my_bucket/keys/my_key

With the addition of bucket types in Riak 2.0, bucket types can be used as an additional namespace on top of buckets and keys. The same bucket name can be associated with completely different data if it used in accordance with a different type. Thus, the following two requests will be made to completely different objects, even though the bucket and key names are the same:

Location key1 =
  new Location(new Namespace("type1", "my_bucket"), "my_key");
Location key2 =
  new Location(new Namespace("type2", "my_bucket"), "my_key");
FetchValue fetch1 = new FetchValue.Builder(key1).build();
FetchValue fetch2 = new FetchValue.Builder(key2).build();
client.execute(fetch1);
client.execute(fetch2);
bucket1 = client.bucket_type('type1').bucket('my_bucket')
bucket2 = client.bucket_type('type2').bucket('my_bucket')
bucket1.get('my_key')
bucket2.get('my_key')
$location1 = new \Basho\Riak\Location('my_key', new Bucket('my_bucket', 'type1'));
$location2 = new Location('my_key', new Bucket('my_bucket', 'type2'));
$builder = new \Basho\Riak\Command\Builder\FetchObject($riak);
$builder->atLocation($location1)
  ->build()
  ->execute();
$builder->atLocation($location2)
  ->build()
  ->execute();
bucket1 = client.bucket_type('type1').bucket('my_bucket')
bucket2 = client.bucket_type('type2').bucket('my_bucket')
bucket1.get('my_key')
bucket2.get('my_key')
var id1 = new RiakObjectId("type1", "my_bucket", "my_key");
var id2 = new RiakObjectId("type2", "my_bucket", "my_key");
var rslt1 = client.Get(id1);
var rslt2 = client.Get(id2);
client.fetchValue({
    bucketType: 'type1', bucket: 'my_bucket', key: 'my_key'
}, function (err, rslt) {
});

client.fetchValue({
    bucketType: 'type2', bucket: 'my_bucket', key: 'my_key'
}, function (err, rslt) {
});
{ok, Obj1} = riakc_pb_socket:get(Pid,
                                 {<<"type1">>, <<"my_bucket">>},
                                 <<"my_key">>),
{ok, Obj2} = riakc_pb_socket:get(Pid,
                                 {<<"type2">>, <<"my_bucket">>},
                                 <<"my_key">>).
curl http://localhost:8098/types/type1/buckets/my_bucket/keys/my_key
curl http://localhost:8098/types/type2/buckets/my_bucket/keys/my_key
Note on object location
In Riak 2.x, all requests must be made to a location specified by a bucket type, bucket, and key rather than to a bucket/key pair, as in previous versions.

If requests are made to a bucket/key pair without a specified bucket type, default will be used in place of a bucket type. The following queries are thus identical:

Location withDefaultBucketType =
  new Location(new Namespace("default", "my_bucket"), "my_key");
Location noBucketType =
  new Location(new Namespace("my_bucket"), "my_key");
FetchValue fetch1 = new FetchValue.Builder(withDefaultBucketType).build();
FetchValue fetch2 = new FetchValue.Builder(noBucketType).build();
client.execute(fetch1);
client.execute(fetch2);
bucket1 = client.bucket_type('default').bucket('my_bucket')
bucket2 = client.bucket('my_bucket')
bucket1.get('my_key')
bucket2.get('my_key')
$location1 = new \Basho\Riak\Location('my_key', new Bucket('my_bucket', 'default'));
$location2 = new \Basho\Riak\Location('my_key', new Bucket('my_bucket'));
$builder = new \Basho\Riak\Command\Builder\FetchObject($riak);
$builder->atLocation($location1)
  ->build()
  ->execute();
$builder->atLocation($location2)
  ->build()
  ->execute();
bucket1 = client.bucket_type('default').bucket('my_bucket')
bucket2 = client.bucket('my_bucket')
bucket1.get('my_key')
bucket2.get('my_key')
var id1 = new RiakObjectId("default", "my_bucket", "my_key");
var obj1 = new RiakObject(id1, "value", RiakConstants.ContentTypes.TextPlain);
client.Put(obj1);

var id2 = new RiakObjectId("my_bucket", "my_key");
var getRslt = client.Get(id2);

RiakObject obj2 = getRslt.Value;
// Note: obj1.Value and obj2.Value are equal
var obj1 = new Riak.Commands.KV.RiakObject();
obj1.setContentType('text/plain');
obj1.setBucketType('default');
obj1.setBucket('my_bucket');
obj1.setKey('my_key');
obj1.setValue('value');
client.storeValue({ value: obj1 }, function (err, rslt) {
    if (err) {
        throw new Error(err);
    }

    client.fetchValue({
        bucketType: 'default', bucket: 'my_bucket', key: 'my_key'
    }, function (err, rslt) {
        if (err) {
            throw new Error(err);
        }
        var obj2 = rslt.values.shift();
        assert(obj1.value == obj2.value);
    });
});
{ok, Obj1} = riakc_pb_socket:get(Pid,
                                 {<<"default">>, <<"my_bucket">>},
                                 <<"my_key">>),
{ok, Obj2} = riakc_pb_socket:get(Pid,
                                 <<"my_bucket">>,
                                 <<"my_key">>).
curl http://localhost:8098/buckets/my_bucket/keys/my_key
curl http://localhost:8098/types/default/my_bucket/keys/my_key

Default Bucket Properties

Below is a listing of the default bucket properties (i.e. props) associated with the default bucket type:

{
  "props": {
    "allow_mult": false,
    "basic_quorum": false,
    "big_vclock": 50,
    "chash_keyfun": {
      "fun": "chash_std_keyfun",
      "mod": "riak_core_util"
    },
    "dvv_enabled": false,
    "dw": "quorum",
    "last_write_wins": false,
    "linkfun": {
      "fun": "mapreduce_linkfun",
      "mod": "riak_kv_wm_link_walker"
    },
    "n_val": 3,
    "notfound_ok": true,
    "old_vclock": 86400,
    "postcommit": [],
    "pr": 0,
    "precommit": [],
    "pw": 0,
    "r": "quorum",
    "rw": "quorum",
    "small_vclock": 50,
    "w": "quorum",
    "young_vclock": 20
  }
}

Bucket Types and the allow_mult Setting

Prior to Riak 2.0, Riak created siblings in the case of conflicting updates only when explicitly instructed to do so, i.e. when allow_mult is to true. The default allow_mult setting was false.

In version 2.0, this is changing in a subtle way. Now, there are two different default settings for allow_mult in play:

  • For the default bucket type, allow_mult is set to false by default, as in previous versions of Riak
  • For all newly-created bucket types, the default is now true. It is possible to set allow_mult to false if you wish to avoid resolving sibling conflicts, but this needs to be done explicitly.

The consequence is that applications that have previously ignored conflict resolutions in certain buckets (or all buckets) can continue to do so. New applications, however, are encouraged to retain and resolve siblings with the appropriate application-side business logic.

To give an example, let’s have a look at the properties associated with the default bucket type:

riak-admin bucket-type status default | grep allow_mult

The output:

allow_mult: false

Now, let’s create a new bucket type called n_val_of_2, which sets the n_val to 2 but doesn’t explicitly set allow_mult:

riak-admin bucket-type create n_val_of_2 '{"props":{"n_val":2}}'

When specifying this bucket type’s properties as above, the allow_mult parameter was not changed. However, if we view the bucket type’s properties, we can see in the console output that allow_mult is set to true:

riak-admin bucket-type status n_val_of_2 | grep allow_mult

The output:

allow_mult: true

This is important to bear in mind when using versions of Riak 2.0 and later any time that you create, activate, and use your own bucket types. It is still possible to set allow_mult to false in any given bucket type, but it must be done explicitly. If we wanted to set allow_mult to false in our n_val_of_2 bucket type from above, we would need to create or modify the already existing type as follows:

riak-admin bucket-type update n_val_of_2 '{"props":{"allow_mult":false}}'

Bucket Type Example

Let’s say that you’d like to create a bucket type called user_account_bucket with a pre-commit hook called syntax_check and two post-commit hooks called welcome_email and update_registry. This would involve four steps:

  1. Creating a JavaScript object containing the appropriate props settings:

    {
      "props": {
        "precommit": ["syntax_check"],
        "postcommit": ["welcome_email", "update_registry"]
      }
    }
    
  2. Passing that JSON to the bucket-type create command:

    riak-admin bucket-type create user_account_bucket '{"props":{"precommit": ["syntax_check"], ... }}'
    

    If creation is successful, the console will return user_account_bucket created.

  3. Verifying that the type is ready to be activated:

    Once the type is created, you can check whether your new type is ready to be activated by running:

    riak-admin bucket-type status user_account_bucket
    

    If the first line reads user_account_bucket has been created and may be activated, then you can proceed to the next step. If it reads user_account_bucket has been created and is not ready to activate, then wait a moment and try again. If it still does not work, then there may be network partition or other issues that need to be addressed in your cluster.

  4. Activating the new bucket type:

    riak-admin bucket-type activate user_account_bucket
    

    If activation is successful, the console will return user_account_bucket has been activated. The bucket type is now ready to be used.

Client Usage Example

If you have created the bucket type no_siblings (with the property allow_mult set to false) and would like that type to be applied to the bucket sensitive_user_data, you would need to run operations on that bucket in accordance with the format above. Here is an example write:

Location key = new Location("sensitive_user_data")
        .setBucketType("no_siblings")
        .setKey("user19735");
RiakObject obj = new RiakObject()
        .setContentType("application/json")
        .setValue(BinaryValue.create("{ ... user data ... }"));
StoreValue store = new StoreValue.Builder(obj).build();
client.execute(store);
bucket = client.bucket_type('no_siblings').bucket('sensitive_user_data')
obj = Riak::RObject.new(bucket, 'user19735')
obj.content_type = 'application/json'
obj.raw_data = '{ ... user data ... }'
obj.store
(new \Basho\Riak\Command\Builder\StoreObject($riak))
  ->buildJsonObject("{ ... user data ... }")
  ->buildLocation('user19735', 'sensitive_user_data', 'no_siblings')
  ->build()
  ->execute();
bucket = client.bucket_type('no_siblings').bucket('sensitive_user_data')
obj = RiakObject(client, bucket, 'user19735')
obj.content_type = 'application/json'
obj.data = '{ ... user data ... }'
obj.store()
var id = new RiakObjectId("no_siblings", "sensitive_user_data", "user19735");
var obj = new RiakObject(id, "{\"name\":\"Bob\"}");
var rslt = client.Put(obj);
var obj = { name: 'Bob' };
client.storeValue({
    bucketType: 'no_siblings', bucket: 'sensitive_user_data',
    key: 'user19735', value: obj
}, function (err, rslt) {
    if (err) {
        throw new Error(err);
    }
});
Object = riakc_obj:new({<<"no_siblings">>, <<"sensitive_user_data">>},
                       <<"user19735">>,
                       <<"{ ... user data ... }">>,
                       <<"application/json">>),
riakc_pb_socket:put(Pid, Object).
curl -XPUT \
  -H "Content-Type: application/json" \
  -d "{ ... user data ... }" \
  http://localhost:8098/types/no_siblings/buckets/sensitive_user_data/keys/user19735

In this example, the bucket sensitive_user_data bears the configuration established by the no_siblings bucket type, and it bears that configuration on the basis of the query’s structure. This is because buckets act as a separate namespace in Riak, in addition to buckets and keys.

Let’s say that we’re using Riak to store internet memes. We’ve been using a bucket called current_memes using the bucket type no_siblings (from above). At a certain point, we decide that our application needs to use a new bucket called old_memes to store memes that have gone woefully out of fashion, but that bucket also needs to bear the type no_siblings.

The following request seeks to add the meme “all your base are belong to us” to the old_memes bucket. If the bucket type no_siblings has been created and activated, the request will ensure that the old_memes bucket inherits all of the properties from the type no_siblings:

Location allYourBaseKey =
  new Location(new Namespace("no_siblings", "old_memes"), "all_your_base");
RiakObject obj = new RiakObject()
        .setContentType("text/plain")
        .setValue(BinaryValue.create("all your base are belong to us"));
StoreValue store = new StoreValue.Builder(obj).build();
client.execute(store);
bucket = client.bucket_type('no_siblings').bucket('old_memes')
obj = Riak::RObject.new(bucket, 'all_your_base')
obj.content_type = 'text/plain'
obj.raw_data = 'all your base are belong to us'
obj.store
(new \Basho\Riak\Command\Builder\StoreObject($riak))
  ->buildObject("all your base are belong to us", ['Content-Type' => 'text/plain'])
  ->buildLocation('user19735', 'sensitive_user_data', 'no_siblings')
  ->build()
  ->execute();
bucket = client.bucket_type('no_siblings').bucket('old_memes')
obj = RiakObject(client, bucket, 'all_your_base')
obj.content_type = 'text/plain'
obj.data = 'all your base are belong to us'
obj.store()
var id = new RiakObjectId("no_siblings", "old_memes", "all_your_base");
var obj = new RiakObject(id, "all your base are belong to us",
    RiakConstants.ContentTypes.TextPlain);
var rslt = client.Put(obj);
var obj = new Riak.Commands.KV.RiakObject();
obj.setContentType('text/plain');
obj.setBucketType('no_siblings');
obj.setBucket('old_memes');
obj.setKey('all_your_base');
obj.setValue('all your base are belong to us');
client.storeValue({ value: obj }, function (err, rslt) {
    if (err) {
        throw new Error(err);
    }
});
Object = riakc_obj:new({<<"no_siblings">>, <<"old_memes">>},
                       <<"all_your_base">>,
                       <<"all your base are belong to us">>,
                       <<"text/plain">>),
riakc_pb_socket:put(Pid, Object).
curl -XPUT \
  -H "Content-Type: text/plain" \
  -d "all your base are belong to us" \
  http://localhost:8098/types/no_siblings/buckets/old_memes/keys/all_your_base

This query would both create the bucket old_memes and ensure that the configuration contained in the no_siblings bucket type is applied to the bucket all at once.

If we wished, we could also store both old and new memes in buckets with different types. We could use the no_siblings bucket from above if we didn’t want to deal with siblings, vclocks, and the like, and we could use a siblings_allowed bucket type (with all of the default properties except allow_mult set to true). This would give use four bucket type/bucket pairs:

  • no_siblings / old_memes
  • no_siblings / new_memes
  • siblings_allowed / old_memes
  • siblings_allowed / new_memes

All four of these pairs are isolated keyspaces. The key favorite_meme could hold different values in all four bucket type/bucket spaces.