CompressionSettings (SystemDS 2.2.1 API)

java.lang.Object
- org.apache.sysds.runtime.compress.CompressionSettings

```
public class CompressionSettings
extends Object
```
Compression Settings class, used as a bundle of parameters inside the Compression framework. See CompressionSettingsBuilder for default non static parameters.

Field Summary

Fields
Modifier and Type	Field and Description
`boolean`	`allowSharedDictionary` Share DDC Dictionaries between ColGroups.
`static int`	`BITMAP_BLOCK_SZ` Size of the blocks used in a blocked bitmap representation.
`double`	`coCodePercentage` A Cocode parameter that differ in behavior based on compression method, in general it is a value that reflects aggressively likely coCoding is used.
`CoCoderFactory.PartitionerType`	`columnPartitioner` The selected method for column partitioning used in CoCoding compressed columns
`CostEstimatorFactory.CostType`	`costComputationType` The cost computation type for the compression
`SampleEstimatorFactory.EstimationType`	`estimationType` The sample type used for sampling
`boolean`	`isInSparkInstruction` Is a spark instruction
`boolean`	`lossy` True if lossy compression is enabled
`int`	`maxColGroupCoCode` The maximum number of columns CoCoded allowed
`int`	`maxSampleSize` The maximum size of the sample extracted.
`double`	`minimumCompressionRatio` The minimum compression ratio to achieve.
`int`	`minimumSampleSize` The minimum size of the sample extracted.
`double`	`samplingRatio` The sampling ratio used when choosing ColGroups.
`int`	`seed` If the seed is -1 then the system used system millisecond time and class hash for seeding.
`boolean`	`sortValuesByLength` Sorting of values by physical length helps by 10-20%, especially for serial, while slight performance decrease for parallel incl multi-threaded, hence not applied for distributed operations (also because compression time + garbage collection increases)
`boolean`	`transposed` Transpose input matrix, to optimize access when extracting bitmaps.
`String`	`transposeInput` Boolean specifying which transpose setting is used, can be auto, true or false
`EnumSet<AColGroup.CompressionType>`	`validCompressions` Valid Compressions List, containing the ColGroup CompressionTypes that are allowed to be used for the compression Default is to always allow for Uncompromisable ColGroup.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type Method and Description

String toString()
- Methods inherited from class java.lang.Object
  equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`String`	`toString()`

- Field Detail
  - BITMAP_BLOCK_SZ
```
public static final int BITMAP_BLOCK_SZ
```
    Size of the blocks used in a blocked bitmap representation. Note it is exactly Character.MAX_VALUE. This is not Character max value + 1 because it breaks the offsets in cases with fully dense values.
    
    See Also:
    
    Constant Field Values
  - sortValuesByLength
```
public final boolean sortValuesByLength
```
    Sorting of values by physical length helps by 10-20%, especially for serial, while slight performance decrease for parallel incl multi-threaded, hence not applied for distributed operations (also because compression time + garbage collection increases)
  - samplingRatio
```
public final double samplingRatio
```
    The sampling ratio used when choosing ColGroups. Note that, default behavior is to use exact estimator if the number of elements is below 1000.
  - allowSharedDictionary
```
public final boolean allowSharedDictionary
```
    Share DDC Dictionaries between ColGroups.
  - transposeInput
```
public final String transposeInput
```
    Boolean specifying which transpose setting is used, can be auto, true or false
  - seed
```
public final int seed
```
    If the seed is -1 then the system used system millisecond time and class hash for seeding.
  - lossy
```
public final boolean lossy
```
    True if lossy compression is enabled
  - columnPartitioner
```
public final CoCoderFactory.PartitionerType columnPartitioner
```
    The selected method for column partitioning used in CoCoding compressed columns
  - costComputationType
```
public final CostEstimatorFactory.CostType costComputationType
```
    The cost computation type for the compression
  - maxColGroupCoCode
```
public final int maxColGroupCoCode
```
    The maximum number of columns CoCoded allowed
  - coCodePercentage
```
public final double coCodePercentage
```
    A Cocode parameter that differ in behavior based on compression method, in general it is a value that reflects aggressively likely coCoding is used.
  - validCompressions
```
public final EnumSet<AColGroup.CompressionType> validCompressions
```
    Valid Compressions List, containing the ColGroup CompressionTypes that are allowed to be used for the compression Default is to always allow for Uncompromisable ColGroup.
  - minimumSampleSize
```
public final int minimumSampleSize
```
    The minimum size of the sample extracted.
  - maxSampleSize
```
public final int maxSampleSize
```
    The maximum size of the sample extracted.
  - estimationType
```
public final SampleEstimatorFactory.EstimationType estimationType
```
    The sample type used for sampling
  - transposed
```
public boolean transposed
```
    Transpose input matrix, to optimize access when extracting bitmaps. This setting is changed inside the script based on the transposeInput setting. This is intentionally left as a mutable value, since the transposition of the input matrix is decided in phase 3.
  - minimumCompressionRatio
```
public final double minimumCompressionRatio
```
    The minimum compression ratio to achieve.
  - isInSparkInstruction
```
public final boolean isInSparkInstruction
```
    Is a spark instruction
- Method Detail
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class CompressionSettings

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

BITMAP_BLOCK_SZ

sortValuesByLength

samplingRatio

allowSharedDictionary

transposeInput

seed

lossy

columnPartitioner

costComputationType

maxColGroupCoCode

coCodePercentage

validCompressions

minimumSampleSize

maxSampleSize

estimationType

transposed

minimumCompressionRatio

isInSparkInstruction

Method Detail

toString