Bloom Filter

Bloom filter helps prune segments that do not contain any record matching an EQUALITY predicate.

It would be useful for a query like the following:

SELECT COUNT(*) 
FROM baseballStats 
WHERE playerID = 12345

There are 3 parameters to configure the Bloom Filter:

• fpp: False positive probability of the bloom filter (from 0 to 1, 0.05 by default). The lower the fpp , the higher accuracy the bloom filter has, but it will also increase the size of the bloom filter.

• maxSizeInBytes: Maximum size of the bloom filter (unlimited by default). If a certain fpp generates a bloom filter larger than this size, we will increase the fpp to keep the bloom filter size within this limit.

• loadOnHeap: Whether to load the bloom filter using heap memory or off-heap memory (false by default).

There are 2 ways to configure a bloom filter for a table in the table config:

• Default settings

{
  "tableIndexConfig": {
    "bloomFilterColumns": [
      "playerID",
      ...
    ],
    ...
  },
  ...
}

• Customized parameters

{
  "tableIndexConfig": {
    "bloomFilterConfigs": {
      "playerID": {
        "fpp": 0.01,
        "maxSizeInBytes": 1000000,
        "loadOnHeap": true
      },
      ...
    },
    ...
  },
  ...
}

A Bloom Filter can only be applied to dictionary-encoded columns. Support for raw value columns is WIP.