BloomKFilter (Hive Storage API 2.7.2 API)

java.lang.Object
- org.apache.hive.common.util.BloomKFilter

```
public class BloomKFilter
extends Object
```
BloomKFilter is variation of BloomFilter. Unlike BloomFilter, BloomKFilter will spread 'k' hash bits within same cache line for better L1 cache performance. The way it works is, First hash code is computed from key which is used to locate the block offset (n-longs in bitset constitute a block) Subsequent 'k' hash codes are used to spread hash bits within the block. By default block size is chosen as 8, which is to match cache line size (8 longs = 64 bytes = cache line size). Refer addBytes(byte[]) for more info. This implementation has much lesser L1 data cache misses than BloomFilter.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class BloomKFilter.BitSet
Bare metal bit set implementation.

Nested Classes
Modifier and Type	Class and Description
`static class`	`BloomKFilter.BitSet` Bare metal bit set implementation.

Field Summary

Fields
Modifier and Type Field and Description

static float DEFAULT_FPP

static int START_OF_SERIALIZED_LONGS

Fields
Modifier and Type	Field and Description
`static float`	`DEFAULT_FPP`
`static int`	`START_OF_SERIALIZED_LONGS`

Constructor Summary

Constructors
Constructor and Description
`BloomKFilter(long maxNumEntries)`
`BloomKFilter(long[] bits, int numFuncs)` A constructor to support rebuilding the BloomFilter from a serialized representation.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`add(byte[] val)`
`void`	`addByte(byte val)`
`void`	`addBytes(byte[] val)`
`void`	`addBytes(byte[] val, int offset, int length)`
`void`	`addDouble(double val)`
`void`	`addFloat(float val)`
`void`	`addInt(int val)`
`void`	`addLong(long val)`
`void`	`addString(String val)`
`static BloomKFilter`	`deserialize(InputStream in)` Deserialize a bloom filter Read a byte stream, which was written by serialize(OutputStream, BloomKFilter) into a `BloomKFilter`
`long[]`	`getBitSet()`
`int`	`getBitSize()`
`int`	`getNumBits()`
`int`	`getNumHashFunctions()`
`void`	`merge(BloomKFilter that)` Merge the specified bloom filter with current bloom filter.
`static void`	`mergeBloomFilterBytes(byte[] bf1Bytes, int bf1Start, int bf1Length, byte[] bf2Bytes, int bf2Start, int bf2Length)` Merges BloomKFilter bf2 into bf1.
`void`	`reset()`
`static void`	`serialize(OutputStream out, BloomKFilter bloomFilter)` Serialize a bloom filter
`long`	`sizeInBytes()`
`boolean`	`test(byte[] val)`
`boolean`	`testByte(byte val)`
`boolean`	`testBytes(byte[] val)`
`boolean`	`testBytes(byte[] val, int offset, int length)`
`boolean`	`testDouble(double val)`
`boolean`	`testFloat(float val)`
`boolean`	`testInt(int val)`
`boolean`	`testLong(long val)`
`boolean`	`testString(String val)`
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail
- DEFAULT_FPP
```
public static final float DEFAULT_FPP
```
  See Also:
  
  Constant Field Values
- START_OF_SERIALIZED_LONGS
```
public static final int START_OF_SERIALIZED_LONGS
```
  See Also:
  
  Constant Field Values

Constructor Detail
- BloomKFilter
```
public BloomKFilter(long maxNumEntries)
```
- BloomKFilter
```
public BloomKFilter(long[] bits,
                    int numFuncs)
```
  A constructor to support rebuilding the BloomFilter from a serialized representation.
  
  Parameters:
  
  bits -
  
  numFuncs -

Method Detail

add
```
public void add(byte[] val)
```

addBytes

public void addBytes(byte[] val,
                     int offset,
                     int length)

addBytes
```
public void addBytes(byte[] val)
```

addString
```
public void addString(String val)
```

addByte
```
public void addByte(byte val)
```

addInt
```
public void addInt(int val)
```

addLong
```
public void addLong(long val)
```

addFloat
```
public void addFloat(float val)
```

addDouble
```
public void addDouble(double val)
```

test
```
public boolean test(byte[] val)
```

testBytes
```
public boolean testBytes(byte[] val)
```

testBytes

public boolean testBytes(byte[] val,
                         int offset,
                         int length)

testString

public boolean testString(String val)

testByte
```
public boolean testByte(byte val)
```

testInt
```
public boolean testInt(int val)
```

testLong
```
public boolean testLong(long val)
```

testFloat
```
public boolean testFloat(float val)
```

testDouble

public boolean testDouble(double val)

sizeInBytes
```
public long sizeInBytes()
```

getBitSize
```
public int getBitSize()
```

getNumHashFunctions
```
public int getNumHashFunctions()
```

getNumBits
```
public int getNumBits()
```

getBitSet
```
public long[] getBitSet()
```

toString
```
public String toString()
```
Overrides:

toString in class Object

merge
```
public void merge(BloomKFilter that)
```
Merge the specified bloom filter with current bloom filter.

Parameters:

that - - bloom filter to merge

reset
```
public void reset()
```

serialize

public static void serialize(OutputStream out,
                             BloomKFilter bloomFilter)
                      throws IOException

Serialize a bloom filter

Parameters:: out - output stream to write to; bloomFilter - BloomKFilter that needs to be seralized
Throws:: IOException

deserialize
```
public static BloomKFilter deserialize(InputStream in)
                                throws IOException
```
Deserialize a bloom filter Read a byte stream, which was written by serialize(OutputStream, BloomKFilter) into a BloomKFilter

Parameters:

in - input bytestream

Returns:

deserialized BloomKFilter

Throws:

IOException

mergeBloomFilterBytes

public static void mergeBloomFilterBytes(byte[] bf1Bytes,
                                         int bf1Start,
                                         int bf1Length,
                                         byte[] bf2Bytes,
                                         int bf2Start,
                                         int bf2Length)

Merges BloomKFilter bf2 into bf1. Assumes 2 BloomKFilters with the same size/hash functions are serialized to byte arrays

Parameters:: bf1Bytes -; bf1Start -; bf1Length -; bf2Bytes -; bf2Start -; bf2Length -

Class BloomKFilter

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_FPP

START_OF_SERIALIZED_LONGS

Constructor Detail

BloomKFilter

BloomKFilter

Method Detail

add

addBytes

addBytes

addString

addByte

addInt

addLong

addFloat

addDouble

test

testBytes

testBytes

testString

testByte

testInt

testLong

testFloat

testDouble

sizeInBytes

getBitSize

getNumHashFunctions

getNumBits

getBitSet

toString

merge

reset

serialize

deserialize

mergeBloomFilterBytes