---
categories:
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- develop
- stack
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- oss
- kubernetes
- clients
description: Redis probabilistic data structures support multiple configuration parameters.
linkTitle: Configuration
title: Configuration Parameters
weight: 100
---
{{< note >}}
As of Redis 8 in Redis Open Source (Redis 8), configuration parameters for the probabilistic data structures are now set in the following ways:
* At load time via your `redis.conf` file.
* At run time (where applicable) using the [`CONFIG SET`]({{< relref "/commands/config-set" >}}) command.

Also, Redis 8 persists probabilistic configuration parameters just like any other configuration parameters (e.g., using the [`CONFIG REWRITE`]({{< relref "/commands/config-rewrite/" >}}) command).
{{< /note >}}


## Redis probabilistic data structure configuration parameters

The following table summarizes which Bloom filter configuration parameters can be set at run-time, and compatibility with Redis Software and Redis Cloud.

| Parameter name<br />(version < 8.0) | Parameter name<br />(version &#8805; 8.0) | Run-time | Redis<br />Software | Redis<br />Cloud |
| :------- | :------- | :------- | :------- | :------- |
| ERROR_RATE         | [bf-error-rate](#bf-error-rate)             | :white_check_mark: | <span title="Supported">&#x2705; Supported</span><br /><span><br /></span> | <span title="Supported">&#x2705; Flexible & Annual</span><br /><span title="Not supported"><nobr>&#x274c; Free & Fixed</nobr></span> |
|                    | [bf-expansion-factor](#bf-expansion-factor) | :white_check_mark: |||
| INITIAL_SIZE       | [bf-initial-size](#bf-initial-size)         | :white_check_mark: | <span title="Supported">&#x2705; Supported</span><br /><span><br /></span> | <span title="Supported">&#x2705; Flexible & Annual</span><br /><span title="Not supported"><nobr>&#x274c; Free & Fixed</nobr></span> |

The following table summarizes which Cuckoo filter configuration parameters can be set at run-time, and compatibility with Redis Software and Redis Cloud.

| Parameter name<br />(version < 8.0) | Parameter name<br />(version &#8805; 8.0) | Run-time | Redis<br />Software | Redis<br />Cloud |
| :------- | :------- | :------- | :------- | :------- |
|                    | [cf-bucket-size](#cf-bucket-size)           | :white_check_mark: |||
|                    | [cf-initial-size](#cf-initial-size)         | :white_check_mark: |||
|                    | [cf-expansion-factor](#cf-expansion-factor) | :white_check_mark: |||
| CF_MAX_EXPANSIONS  | [cf-max-expansions](#cf-max-expansions)     | :white_check_mark: | <span title="Supported">&#x2705; Supported</span><br /><span><br /></span> | <span title="Supported">&#x2705; Flexible & Annual</span><br /><span title="Not supported"><nobr>&#x274c; Free & Fixed</nobr></span> |
|                    | [cf-max-iterations](#cf-max-iterations)     | :white_check_mark: |||

{{< note >}}
Parameter names for Redis Open Source versions < 8.0, while deprecated, will still be supported in Redis 8.
{{< /note >}}

See also [Redis configuration]({{< relref "/operate/oss_and_stack/management/config" >}}).

---

{{< warning >}}
A filter should always be sized for the expected capacity and the desired error rate.
Using the `INSERT` family commands with the default values should be used in cases where many small filters exist and the expectation is most will remain at around the default sizes.
Not optimizing a filter for its intended use will result in degradation of performance and memory efficiency.
{{< /warning >}}

## Default parameters for Bloom filters

### bf-error-rate

Default false positive rate for Bloom filters.

Type: double

Valid range: `(0 .. 1)`. Though the valid range is `(0 .. 1)` (corresponding to `> 0%` to `< 100%` false positive rate), any value greater than `0.25` is treated as `0.25`.

Default: `0.01`

### bf-expansion-factor

Added in v8.0.0.

Expansion factor for Bloom filters.

Type: integer

Valid range: `[0 .. 32768]`.

Default: `2`

### bf-initial-size

Initial capacity for Bloom filters.

Type: integer

Valid range: `[1 .. 1048576]`

Default: `100`

## Default parameters for Cuckoo filters

### cf-bucket-size

Added in v8.0.0.

The number of items in each Cuckoo filter bucket.

Type: integer

Valid range: `[1 .. 255]`

Default: `2`

### cf-initial-size

Added in v8.0.0.

Cuckoo filter initial capacity.

Type: integer

Valid range: `[2*cf-bucket-size .. 1048576]`

Default: `1024`

### cf-expansion-factor

Added in v8.0.0.

Expansion factor for Cuckoo filters.

Type: integer

Valid range: `[0 .. 32768]`

Default: `1`

### cf-max-expansions

The maximum number of expansions for Cuckoo filters.

Type: integer

Valid range: `[1 .. 65535]`

Default: `32`

### cf-max-iterations

Added in v8.0.0

The maximum number of iterations for Cuckoo filters.

Type: integer

Valid range: `[1 .. 65535]`

Default: `20`

## Setting configuration parameters on module load (deprecated)

These methods are deprecated beginning with Redis 8.

Setting configuration parameters at load-time is done by appending arguments after the `--loadmodule` argument when starting a server from the command line or after the `loadmodule` directive in a Redis config file. For example:

In [redis.conf]({{< relref "/operate/oss_and_stack/management/config" >}}):

```sh
loadmodule ./redisbloom.so [OPT VAL]...
```

From the [Redis CLI]({{< relref "/develop/tools/cli" >}}), using the [MODULE LOAD]({{< relref "/commands/module-load" >}}) command:

```
127.0.0.6379> MODULE LOAD redisbloom.so [OPT VAL]...
```

From the command line:

```sh
$ redis-server --loadmodule ./redisbloom.so [OPT VAL]...
```