BF.INSERT key [CAPACITY capacity] [ERROR error]
  [EXPANSION expansion] [NOCREATE] [NONSCALING] ITEMS item [item
Available in:
Redis Stack / Bloom 1.0.0
Time complexity:
O(k * n), where k is the number of hash functions and n is the number of items

Creates a new Bloom filter if the key does not exist using the specified error rate, capacity, and expansion, then adds all specified items to the Bloom Filter.

This command is similar to BF.MADD, except that the error rate, capacity, and expansion can be specified. It is a sugarcoated combination of BF.RESERVE and BF.MADD.

Required arguments


is key name for a Bloom filter to add items to.

If key does not exist, a new Bloom filter is created.

ITEMS item...

One or more items to add.

Optional arguments


Indicates that the filter should not be created if it does not already exist. If the filter does not yet exist, an error is returned rather than creating it automatically. This may be used where a strict separation between filter creation and filter addition is desired. It is an error to specify NOCREATE together with either CAPACITY or ERROR.

CAPACITY capacity

Specifies the desired capacity for the filter to be created. This parameter is ignored if the filter already exists. If the filter is automatically created and this parameter is absent, then the module-level capacity is used. See BF.RESERVE for more information about the impact of this value.

ERROR error

Specifies the error ratio of the newly created filter if it does not yet exist. If the filter is automatically created and error is not specified then the module-level error rate is used. See BF.RESERVE for more information about the format of this value.


Prevents the filter from creating additional sub-filters if initial capacity is reached. Non-scaling filters require slightly less memory than their scaling counterparts. The filter returns an error when capacity is reached.

EXPANSION expansion

When capacity is reached, an additional sub-filter is created. The size of the new sub-filter is the size of the last sub-filter multiplied by expansion, specified as a positive integer.

If the number of elements to be stored in the filter is unknown, use an expansion of 2 or more to reduce the number of sub-filters. Otherwise, use an expansion of 1 to reduce memory consumption. The default value is 2.

Return value

Returns one of these replies:

  • Array reply where each element is one of these options:
    • Integer reply, where 1 denotes that the item has been added successfully, and 0 means that such item had already added to the filter (which could be wrong)
    • Error reply when the item cannot be added because the filter is full
  • Error reply, for example, when the number of arguments or key type is wrong, and also when NOCREATE is specified and key does not exist.


Add three items to a filter, then create the filter with default parameters if it does not already exist.

BF.INSERT filter ITEMS foo bar baz

Add one item to a filter, then create the filter with a capacity of 10000 if it does not already exist.

BF.INSERT filter CAPACITY 10000 ITEMS hello

Add two items to a filter, then return error if the filter does not already exist.

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