Package com.illumon.iris.db.v2.sources.sparse

Class SparseConstants

java.lang.Object

com.illumon.iris.db.v2.sources.sparse.SparseConstants

public class SparseConstants
extends Object

Field Summary

Fields

Modifier and Type	Field	Description
static int	BLOCK_SIZE
static int	BLOCK0_MASK
static int	BLOCK0_SHIFT
static int	BLOCK0_SIZE
static int	BLOCK1_MASK
static int	BLOCK1_SHIFT
static int	BLOCK1_SIZE
static int	BLOCK2_MASK
static int	BLOCK2_SHIFT
static int	BLOCK2_SIZE
static int	IN_USE_BLOCK_SIZE
static int	IN_USE_MASK
static long	INDEX_MASK
static int	LOG_BLOCK_SIZE
static int	LOG_BLOCK0_SIZE
static int	LOG_BLOCK1_SIZE
static int	LOG_BLOCK2_SIZE
static int	LOG_INUSE_BITSET_SIZE
static int	LOG_INUSE_BLOCK_SIZE

Constructor Summary

Constructors

Constructor	Description
SparseConstants()

Method Summary

Modifier and Type	Method	Description
static boolean	sparseStructureExceedsOverhead(ReadOnlyIndex index, double maximumOverhead)	When using sparse data structures, a single entry within a block can result in the data size increasing by a factor of BLOCK_SIZE.

Methods inherited from class java.lang.Object

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

Field Details

LOG_BLOCK0_SIZE

public static final int LOG_BLOCK0_SIZE

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LOG_BLOCK1_SIZE

public static final int LOG_BLOCK1_SIZE

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LOG_BLOCK2_SIZE

public static final int LOG_BLOCK2_SIZE

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LOG_BLOCK_SIZE

public static final int LOG_BLOCK_SIZE

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BLOCK0_SHIFT

public static final int BLOCK0_SHIFT

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BLOCK1_SHIFT

public static final int BLOCK1_SHIFT

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BLOCK2_SHIFT

public static final int BLOCK2_SHIFT

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INDEX_MASK

public static final long INDEX_MASK

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BLOCK0_MASK

public static final int BLOCK0_MASK

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BLOCK1_MASK

public static final int BLOCK1_MASK

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BLOCK2_MASK

public static final int BLOCK2_MASK

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BLOCK_SIZE

public static final int BLOCK_SIZE

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BLOCK0_SIZE

public static final int BLOCK0_SIZE

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BLOCK1_SIZE

public static final int BLOCK1_SIZE

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BLOCK2_SIZE

public static final int BLOCK2_SIZE

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LOG_INUSE_BITSET_SIZE

public static final int LOG_INUSE_BITSET_SIZE

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LOG_INUSE_BLOCK_SIZE

public static final int LOG_INUSE_BLOCK_SIZE

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IN_USE_BLOCK_SIZE

public static final int IN_USE_BLOCK_SIZE

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IN_USE_MASK

public static final int IN_USE_MASK

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Constant Field Values

Constructor Details

SparseConstants

public SparseConstants()

Method Details

sparseStructureExceedsOverhead

public static boolean sparseStructureExceedsOverhead(ReadOnlyIndex index, double maximumOverhead)

When using sparse data structures, a single entry within a block can result in the data size increasing by a factor of BLOCK_SIZE. On the other hand, we would strongly prefer the sparse results because they are generally much faster than the alternatives.

To balance those concerns, we can determine if a given index exceeds some overhead threshold and act accordingly.

Parameters:

index - the Index that we should calculate the overhead for

maximumOverhead - the maximum overhead as a fraction (e.g. 1.1 is 10% overhead). Values less than zero disable overhead checking, and result in always using the sparse structure. A value of zero results in never using the sparse structure.