org.rocksdb

Class PlainTableConfig

java.lang.Object

org.rocksdb.TableFormatConfig

org.rocksdb.PlainTableConfig

public class PlainTableConfig
extends TableFormatConfig

The config for plain table sst format.

PlainTable is a RocksDB's SST file format optimized for low query latency on pure-memory or really low-latency media.

It also support prefix hash feature.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_BLOOM_BITS_PER_KEY
static EncodingType	DEFAULT_ENCODING_TYPE
static boolean	DEFAULT_FULL_SCAN_MODE
static double	DEFAULT_HASH_TABLE_RATIO
static int	DEFAULT_HUGE_TLB_SIZE
static int	DEFAULT_INDEX_SPARSENESS
static boolean	DEFAULT_STORE_INDEX_IN_FILE
static int	VARIABLE_LENGTH

Constructor Summary

Constructors

Constructor and Description
PlainTableConfig()

Method Summary

Modifier and Type	Method and Description
int	bloomBitsPerKey()
EncodingType	encodingType() Returns the active EncodingType
boolean	fullScanMode() Return if full scan mode is active
double	hashTableRatio()
int	hugePageTlbSize() Returns the value for huge page tlb size
long	indexSparseness()
int	keySize()
protected long	newTableFactoryHandle() This function should only be called by Options.setTableFormatConfig(), which will create a c++ shared-pointer to the c++ TableFactory that associated with the Java TableFormatConfig.
PlainTableConfig	setBloomBitsPerKey(int bitsPerKey) Set the number of bits per key used by the internal bloom filter in the plain table sst format.
PlainTableConfig	setEncodingType(EncodingType encodingType) Sets the encoding type.
PlainTableConfig	setFullScanMode(boolean fullScanMode) Set full scan mode, if true the whole file will be read one record by one without using the index.
PlainTableConfig	setHashTableRatio(double ratio) hashTableRatio is the desired utilization of the hash table used for prefix hashing.
PlainTableConfig	setHugePageTlbSize(int hugePageTlbSize) huge_page_tlb_size: if ≤0, allocate hash indexes and blooms from malloc otherwise from huge page TLB.
PlainTableConfig	setIndexSparseness(int sparseness) Index sparseness determines the index interval for keys inside the same prefix.
PlainTableConfig	setKeySize(int keySize) Set the length of the user key.
PlainTableConfig	setStoreIndexInFile(boolean storeIndexInFile) If set to true: compute plain table index and bloom filter during file building and store it in file.
boolean	storeIndexInFile() Return a boolean value indicating if index shall be stored in a file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

VARIABLE_LENGTH

public static final int VARIABLE_LENGTH

See Also:

Constant Field Values

DEFAULT_BLOOM_BITS_PER_KEY

public static final int DEFAULT_BLOOM_BITS_PER_KEY

See Also:

Constant Field Values

DEFAULT_HASH_TABLE_RATIO

public static final double DEFAULT_HASH_TABLE_RATIO

See Also:

Constant Field Values

DEFAULT_INDEX_SPARSENESS

public static final int DEFAULT_INDEX_SPARSENESS

See Also:

Constant Field Values

DEFAULT_HUGE_TLB_SIZE

public static final int DEFAULT_HUGE_TLB_SIZE

See Also:

Constant Field Values

DEFAULT_ENCODING_TYPE

public static final EncodingType DEFAULT_ENCODING_TYPE

DEFAULT_FULL_SCAN_MODE

public static final boolean DEFAULT_FULL_SCAN_MODE

See Also:

Constant Field Values

DEFAULT_STORE_INDEX_IN_FILE

public static final boolean DEFAULT_STORE_INDEX_IN_FILE

See Also:

Constant Field Values

Constructor Detail

PlainTableConfig

public PlainTableConfig()

Method Detail

setKeySize

public PlainTableConfig setKeySize(int keySize)

Set the length of the user key. If it is set to be VARIABLE_LENGTH, then it indicates the user keys are of variable length.

Otherwise,all the keys need to have the same length in byte.

DEFAULT: VARIABLE_LENGTH

Parameters:

keySize - the length of the user key.

Returns:

the reference to the current config.

keySize

public int keySize()

Returns:

the specified size of the user key. If VARIABLE_LENGTH, then it indicates variable-length key.

setBloomBitsPerKey

public PlainTableConfig setBloomBitsPerKey(int bitsPerKey)

Set the number of bits per key used by the internal bloom filter in the plain table sst format.

Parameters:

bitsPerKey - the number of bits per key for bloom filer.

Returns:

the reference to the current config.

bloomBitsPerKey

public int bloomBitsPerKey()

Returns:

the number of bits per key used for the bloom filter.

setHashTableRatio

public PlainTableConfig setHashTableRatio(double ratio)

hashTableRatio is the desired utilization of the hash table used for prefix hashing. The ideal ratio would be the number of prefixes / the number of hash buckets. If this value is set to zero, then hash table will not be used.

Parameters:

ratio - the hash table ratio.

Returns:

the reference to the current config.

hashTableRatio

public double hashTableRatio()

Returns:

the hash table ratio.

setIndexSparseness

public PlainTableConfig setIndexSparseness(int sparseness)

Index sparseness determines the index interval for keys inside the same prefix. This number is equal to the maximum number of linear search required after hash and binary search. If it's set to 0, then each key will be indexed.

Parameters:

sparseness - the index sparseness.

Returns:

the reference to the current config.

indexSparseness

public long indexSparseness()

Returns:

the index sparseness.

setHugePageTlbSize

public PlainTableConfig setHugePageTlbSize(int hugePageTlbSize)

huge_page_tlb_size: if ≤0, allocate hash indexes and blooms from malloc otherwise from huge page TLB.

The user needs to reserve huge pages for it to be allocated, like: sysctl -w vm.nr_hugepages=20

See linux doc Documentation/vm/hugetlbpage.txt

Parameters:

hugePageTlbSize - huge page tlb size

Returns:

the reference to the current config.

hugePageTlbSize

public int hugePageTlbSize()

Returns the value for huge page tlb size

Returns:

hugePageTlbSize

setEncodingType

public PlainTableConfig setEncodingType(EncodingType encodingType)

Sets the encoding type.

This setting determines how to encode the keys. See enum EncodingType for the choices.

The value will determine how to encode keys when writing to a new SST file. This value will be stored inside the SST file which will be used when reading from the file, which makes it possible for users to choose different encoding type when reopening a DB. Files with different encoding types can co-exist in the same DB and can be read.

Parameters:

encodingType - EncodingType value.

Returns:

the reference to the current config.

encodingType

public EncodingType encodingType()

Returns the active EncodingType

Returns:

currently set encoding type

setFullScanMode

public PlainTableConfig setFullScanMode(boolean fullScanMode)

Set full scan mode, if true the whole file will be read one record by one without using the index.

Parameters:

fullScanMode - boolean value indicating if full scan mode shall be enabled.

Returns:

the reference to the current config.

fullScanMode

public boolean fullScanMode()

Return if full scan mode is active

Returns:

boolean value indicating if the full scan mode is enabled.

setStoreIndexInFile

public PlainTableConfig setStoreIndexInFile(boolean storeIndexInFile)

If set to true: compute plain table index and bloom filter during file building and store it in file. When reading file, index will be mmaped instead of doing recomputation.

Parameters:

storeIndexInFile - value indicating if index shall be stored in a file

Returns:

the reference to the current config.

storeIndexInFile

public boolean storeIndexInFile()

Return a boolean value indicating if index shall be stored in a file.

Returns:

currently set value for store index in file.

newTableFactoryHandle

protected long newTableFactoryHandle()

Description copied from class: TableFormatConfig

This function should only be called by Options.setTableFormatConfig(), which will create a c++ shared-pointer to the c++ TableFactory that associated with the Java TableFormatConfig.

Specified by:

newTableFactoryHandle in class TableFormatConfig

Returns:

native handle address to native table instance.