java.lang.Object
- org.apache.iceberg.actions.BinPackStrategy

All Implemented Interfaces:

java.io.Serializable, RewriteStrategy

Direct Known Subclasses:

SortStrategy, Spark3BinPackStrategy
```
public abstract class BinPackStrategy
extends java.lang.Object
implements RewriteStrategy
```
A rewrite strategy for data files which determines which files to rewrite based on their size. If files are either smaller than the MIN_FILE_SIZE_BYTES threshold or larger than the MAX_FILE_SIZE_BYTES threshold, they are considered targets for being rewritten.
Once selected files are grouped based on a BinPacking into groups defined by RewriteDataFiles.MAX_FILE_GROUP_SIZE_BYTES. Groups will be considered for rewriting if they contain more files than MIN_INPUT_FILES or would produce at least one file of RewriteDataFiles.TARGET_FILE_SIZE_BYTES.

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field	Description
`static java.lang.String`	`MAX_FILE_SIZE_BYTES`	Adjusts files which will be considered for rewriting.
`static double`	`MAX_FILE_SIZE_DEFAULT_RATIO`
`static java.lang.String`	`MIN_FILE_SIZE_BYTES`	Adjusts files which will be considered for rewriting.
`static double`	`MIN_FILE_SIZE_DEFAULT_RATIO`
`static java.lang.String`	`MIN_INPUT_FILES`	The minimum number of files that need to be in a file group for it to be considered for compaction if the total size of that group is less than the `RewriteDataFiles.TARGET_FILE_SIZE_BYTES`.
`static int`	`MIN_INPUT_FILES_DEFAULT`

Constructor Summary

Constructors
Constructor Description

BinPackStrategy()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected long`	`inputFileSize(java.util.List<FileScanTask> fileToRewrite)`
`java.lang.String`	`name()`	Returns the name of this rewrite strategy
`protected long`	`numOutputFiles(long totalSizeInBytes)`	Determine how many output files to create when rewriting.
`RewriteStrategy`	`options(java.util.Map<java.lang.String,java.lang.String> options)`	Sets options to be used with this strategy
`java.lang.Iterable<java.util.List<FileScanTask>>`	`planFileGroups(java.lang.Iterable<FileScanTask> dataFiles)`	Groups file scans into lists which will be processed in a single executable unit.
`java.lang.Iterable<FileScanTask>`	`selectFilesToRewrite(java.lang.Iterable<FileScanTask> dataFiles)`	Selects files which this strategy believes are valid targets to be rewritten.
`protected long`	`splitSize(long totalSizeInBytes)`	Returns the smaller of our max write file threshold, and our estimated split size based on the number of output files we want to generate.
`protected long`	`targetFileSize()`
`java.util.Set<java.lang.String>`	`validOptions()`	Returns a set of options which this rewrite strategy can use.
`protected long`	`writeMaxFileSize()`	Estimates a larger max target file size than our target size used in task creation to avoid tasks which are predicted to have a certain size, but exceed that target size when serde is complete creating tiny remainder files.

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

Methods inherited from interface org.apache.iceberg.actions.RewriteStrategy
rewriteFiles, table

- Field Detail
  - MIN_INPUT_FILES
```
public static final java.lang.String MIN_INPUT_FILES
```
    The minimum number of files that need to be in a file group for it to be considered for compaction if the total size of that group is less than the RewriteDataFiles.TARGET_FILE_SIZE_BYTES. This can also be thought of as the maximum number of non-target-size files that could remain in a file group (partition) after rewriting.
    
    See Also:
    
    Constant Field Values
  - MIN_INPUT_FILES_DEFAULT
```
public static final int MIN_INPUT_FILES_DEFAULT
```
    See Also:
    
    Constant Field Values
  - MIN_FILE_SIZE_BYTES
```
public static final java.lang.String MIN_FILE_SIZE_BYTES
```
    Adjusts files which will be considered for rewriting. Files smaller than MIN_FILE_SIZE_BYTES will be considered for rewriting. This functions independently of MAX_FILE_SIZE_BYTES.
    Defaults to 75% of the target file size
    
    See Also:
    
    Constant Field Values
  - MIN_FILE_SIZE_DEFAULT_RATIO
```
public static final double MIN_FILE_SIZE_DEFAULT_RATIO
```
    See Also:
    
    Constant Field Values
  - MAX_FILE_SIZE_BYTES
```
public static final java.lang.String MAX_FILE_SIZE_BYTES
```
    Adjusts files which will be considered for rewriting. Files larger than MAX_FILE_SIZE_BYTES will be considered for rewriting. This functions independently of MIN_FILE_SIZE_BYTES.
    Defaults to 180% of the target file size
    
    See Also:
    
    Constant Field Values
  - MAX_FILE_SIZE_DEFAULT_RATIO
```
public static final double MAX_FILE_SIZE_DEFAULT_RATIO
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - BinPackStrategy
```
public BinPackStrategy()
```
- Method Detail
  - name
```
public java.lang.String name()
```
    Description copied from interface: RewriteStrategy
    
    Returns the name of this rewrite strategy
    
    Specified by:
    
    name in interface RewriteStrategy
  - validOptions
```
public java.util.Set<java.lang.String> validOptions()
```
    Description copied from interface: RewriteStrategy
    
    Returns a set of options which this rewrite strategy can use. This is an allowed-list and any options not specified here will be rejected at runtime.
    
    Specified by:
    
    validOptions in interface RewriteStrategy
  - options
```
public RewriteStrategy options(java.util.Map<java.lang.String,java.lang.String> options)
```
    Description copied from interface: RewriteStrategy
    
    Sets options to be used with this strategy
    
    Specified by:
    
    options in interface RewriteStrategy
  - selectFilesToRewrite
```
public java.lang.Iterable<FileScanTask> selectFilesToRewrite(java.lang.Iterable<FileScanTask> dataFiles)
```
    Description copied from interface: RewriteStrategy
    
    Selects files which this strategy believes are valid targets to be rewritten.
    
    Specified by:
    
    selectFilesToRewrite in interface RewriteStrategy
    
    Parameters:
    
    dataFiles - iterable of FileScanTasks for files in a given partition
    
    Returns:
    
    iterable containing only FileScanTasks to be rewritten
  - planFileGroups
```
public java.lang.Iterable<java.util.List<FileScanTask>> planFileGroups(java.lang.Iterable<FileScanTask> dataFiles)
```
    Description copied from interface: RewriteStrategy
    
    Groups file scans into lists which will be processed in a single executable unit. Each group will end up being committed as an independent set of changes. This creates the jobs which will eventually be run as by the underlying Action.
    
    Specified by:
    
    planFileGroups in interface RewriteStrategy
    
    Parameters:
    
    dataFiles - iterable of FileScanTasks to be rewritten
    
    Returns:
    
    iterable of lists of FileScanTasks which will be processed together
  - targetFileSize
```
protected long targetFileSize()
```
  - numOutputFiles
```
protected long numOutputFiles(long totalSizeInBytes)
```
    Determine how many output files to create when rewriting. We use this to determine the split-size we want to use when actually writing files to avoid the following situation.
    If we are writing 10.1 G of data with a target file size of 1G we would end up with 11 files, one of which would only have 0.1g. This would most likely be less preferable to 10 files each of which was 1.01g. So here we decide whether to round up or round down based on what the estimated average file size will be if we ignore the remainder (0.1g). If the new file size is less than 10% greater than the target file size then we will round down when determining the number of output files.
    
    Parameters:
    
    totalSizeInBytes - total data size for a file group
    
    Returns:
    
    the number of files this strategy should create
  - splitSize
```
protected long splitSize(long totalSizeInBytes)
```
    Returns the smaller of our max write file threshold, and our estimated split size based on the number of output files we want to generate.
  - inputFileSize
```
protected long inputFileSize(java.util.List<FileScanTask> fileToRewrite)
```
  - writeMaxFileSize
```
protected long writeMaxFileSize()
```
    Estimates a larger max target file size than our target size used in task creation to avoid tasks which are predicted to have a certain size, but exceed that target size when serde is complete creating tiny remainder files.
    While we create tasks that should all be smaller than our target size there is a chance that the actual data will end up being larger than our target size due to various factors of compression, serialization and other factors outside our control. If this occurs, instead of making a single file that is close in size to our target we would end up producing one file of the target size, and then a small extra file with the remaining data. For example, if our target is 512 MB we may generate a rewrite task that should be 500 MB. When we write the data we may find we actually have to write out 530 MB. If we use the target size while writing we would produced a 512 MB file and a 18 MB file. If instead we use a larger size estimated by this method, then we end up writing a single file.
    
    Returns:
    
    the target size plus one half of the distance between max and target

Class BinPackStrategy

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.iceberg.actions.RewriteStrategy

Field Detail

MIN_INPUT_FILES

MIN_INPUT_FILES_DEFAULT

MIN_FILE_SIZE_BYTES

MIN_FILE_SIZE_DEFAULT_RATIO

MAX_FILE_SIZE_BYTES

MAX_FILE_SIZE_DEFAULT_RATIO

Constructor Detail

BinPackStrategy

Method Detail

name

validOptions

options

selectFilesToRewrite

planFileGroups

targetFileSize

numOutputFiles

splitSize

inputFileSize

writeMaxFileSize