A collection of options to steer the creation of the dataset on disk through Snapshot().

Some settings are output format-dependent. Please refer to the table below for an overview of all options, and to which output format they apply.

Note that for RNTuple, the defaults correspond to those set in RNTupleWriteOptions.

Format	Option	Type	Default	Description
All	`fMode`	`std::string`	"RECREATE"	Creation mode for the output TFile
	`fCompressionAlgorithm`	`ROOT::RCompressionSetting::EAlgorithm`	Zstd	Compression algorithm for the output dataset, defaults to ROOT::RCompressionSetting::EAlgorithm::EValues::kUndefined. This is converted to ZLIB by default for TTree and ZSTD by default for RNTuple
	`fCompressionLevel`	`int`	5	Compression level for the output dataset, defaults to 0 (uncompressed). If the default value of fCompressionAlgorithm is not modified, the compression level is changed to 1 by default for TTree and 5 by default for RNTuple
	`fOutputFormat`	`ROOT::RDF::ESnapshotOutputFormat`	TTree	Which output data format to use
	`fLazy`	`bool`	False	Whether to immediately start the event loop when Snapshot() is called
	`fOverwriteIfExists`	`bool`	False	If `fMode` is "UPDATE", overwrite the object with the same name in the output file already present
	`fVector2RVec`	`bool`	True	Store `std::vector`-type columns as `ROOT::RVec` in the output
	`fIncludeInVariations`	`bool`	False	Include columns that result from a Vary() action in the output
TTree	`fAutoFlush`	`int`	0	AutoFlush setting for the output (see TTree::SetAutoFlush())
	`fSplitLevel`	`int`	99	Split level of the output branches
	`fBasketSize`	`int`	-1	Output basket size (a value of -1 means the TTree default of 32000 B used)
RNTuple	`fApproxZippedClusterSize`	`std::size_t`	128 MiB	Approximate output compressed cluster size
	`fMaxUnzippedClusterSize`	`std::size_t`	1280 MiB	Maximum uncompressed output cluster size
	`fInitialUnzippedPageSize`	`std::size_t`	256 B	Initial output page size before compression
	`fMaxUnzippedPageSize`	`std::size_t`	1 MiB	Maximum allowed output page size before compression
	`fEnablePageChecksums`	`bool`	True	Enable checksumming for output pages
	`fEnableSamePageMerging`	`bool`	True	Enable identical-page deduplication (requires page checksumming enabled)

Definition at line 157 of file RSnapshotOptions.hxx.

Public Types
using	ECAlgo = ROOT::RCompressionSetting::EAlgorithm::EValues

Public Member Functions
	RSnapshotOptions ()=default
	RSnapshotOptions (std::string_view mode, ECAlgo comprAlgo, int comprLevel, int autoFlush, int splitLevel, bool lazy, bool overwriteIfExists=false, bool vector2RVec=true, int basketSize=-1, std::size_t approxZippedClusterSize=128 1024 1024, std::size_t maxUnzippedClusterSize=10 128 1024 1024, std::size_t maxUnzippedPageSize=1024 1024, std::size_t initUnzippedPageSize=256, bool enablePageChecksums=true, bool enableSamePageMerging=true, ESnapshotOutputFormat outputFormat=ESnapshotOutputFormat::kDefault)

Public Attributes
std::size_t	fApproxZippedClusterSize = 128 * 1024 * 1024
	(RNTuple only) Approximate target compressed cluster size
int	fAutoFlush = 0
	(TTree only) AutoFlush value for output tree
int	fBasketSize = -1
	(TTree only) Set a custom basket size option.
ECAlgo	fCompressionAlgorithm = ECAlgo::kUndefined
	Compression algorithm of output file.
int	fCompressionLevel = 0
	Compression level of output file.
bool	fEnablePageChecksums = true
	(RNTuple only) Enable checksumming for pages
bool	fEnableSamePageMerging = true
	(RNTuple only) Enable identical-page deduplication. Requires page checksumming
bool	fIncludeVariations = false
	Include columns that result from a Vary() action.
std::size_t	fInitialUnzippedPageSize = 256
	(RNTuple only) Initial page size before compression
bool	fLazy = false
	Do not start the event loop when Snapshot is called.
std::size_t	fMaxUnzippedClusterSize = 10 * fApproxZippedClusterSize
	(RNTuple only) Maximum uncompressed cluster size
std::size_t	fMaxUnzippedPageSize = 1024 * 1024
	(RNTuple only) Maximum allowed page size before compression
std::string	fMode = "RECREATE"
	Mode of creation of output file.
ESnapshotOutputFormat	fOutputFormat = ESnapshotOutputFormat::kDefault
	Which data format to write to.
bool	fOverwriteIfExists = false
	If fMode is "UPDATE", overwrite object in output file if it already exists.
int	fSplitLevel = 99
	(TTree only) Split level of output tree
bool	fVector2RVec = true
	If set to true will convert std::vector columns to RVec when saving to disk.

#include <ROOT/RSnapshotOptions.hxx>

Member Typedef Documentation

◆ ECAlgo

using ROOT::RDF::RSnapshotOptions::ECAlgo = ROOT::RCompressionSetting::EAlgorithm::EValues

Definition at line 158 of file RSnapshotOptions.hxx.

Constructor & Destructor Documentation

◆ RSnapshotOptions() [1/2]

ROOT::RDF::RSnapshotOptions::RSnapshotOptions ( )

default

◆ RSnapshotOptions() [2/2]

ROOT::RDF::RSnapshotOptions::RSnapshotOptions	(	std::string_view	mode,
		ECAlgo	comprAlgo,
		int	comprLevel,
		int	autoFlush,
		int	splitLevel,
		bool	lazy,
		bool	overwriteIfExists = false,
		bool	vector2RVec = true,
		int	basketSize = -1,
		std::size_t	approxZippedClusterSize = 128 * 1024 * 1024,
		std::size_t	maxUnzippedClusterSize = 10 * 128 * 1024 * 1024,
		std::size_t	maxUnzippedPageSize = 1024 * 1024,
		std::size_t	initUnzippedPageSize = 256,
		bool	enablePageChecksums = true,
		bool	enableSamePageMerging = true,
		ESnapshotOutputFormat	outputFormat = ESnapshotOutputFormat::kDefault )

inline

Definition at line 160 of file RSnapshotOptions.hxx.

Member Data Documentation

◆ fApproxZippedClusterSize

std::size_t ROOT::RDF::RSnapshotOptions::fApproxZippedClusterSize = 128 * 1024 * 1024

(RNTuple only) Approximate target compressed cluster size

Definition at line 203 of file RSnapshotOptions.hxx.

◆ fAutoFlush

int ROOT::RDF::RSnapshotOptions::fAutoFlush = 0

(TTree only) AutoFlush value for output tree

Definition at line 195 of file RSnapshotOptions.hxx.

◆ fBasketSize

int ROOT::RDF::RSnapshotOptions::fBasketSize = -1

(TTree only) Set a custom basket size option.

For more details, see https://root.cern/manual/trees/#baskets-clusters-and-the-tree-header

Definition at line 200 of file RSnapshotOptions.hxx.

◆ fCompressionAlgorithm

ECAlgo ROOT::RDF::RSnapshotOptions::fCompressionAlgorithm = ECAlgo::kUndefined

Compression algorithm of output file.

Definition at line 187 of file RSnapshotOptions.hxx.

◆ fCompressionLevel

int ROOT::RDF::RSnapshotOptions::fCompressionLevel = 0

Compression level of output file.

Definition at line 188 of file RSnapshotOptions.hxx.

◆ fEnablePageChecksums

bool ROOT::RDF::RSnapshotOptions::fEnablePageChecksums = true

(RNTuple only) Enable checksumming for pages

Definition at line 211 of file RSnapshotOptions.hxx.

◆ fEnableSamePageMerging

bool ROOT::RDF::RSnapshotOptions::fEnableSamePageMerging = true

(RNTuple only) Enable identical-page deduplication. Requires page checksumming

Definition at line 213 of file RSnapshotOptions.hxx.

◆ fIncludeVariations

bool ROOT::RDF::RSnapshotOptions::fIncludeVariations = false

Include columns that result from a Vary() action.

Definition at line 192 of file RSnapshotOptions.hxx.

◆ fInitialUnzippedPageSize

std::size_t ROOT::RDF::RSnapshotOptions::fInitialUnzippedPageSize = 256

(RNTuple only) Initial page size before compression

Definition at line 207 of file RSnapshotOptions.hxx.

◆ fLazy

bool ROOT::RDF::RSnapshotOptions::fLazy = false

Do not start the event loop when Snapshot is called.

Definition at line 189 of file RSnapshotOptions.hxx.

◆ fMaxUnzippedClusterSize

std::size_t ROOT::RDF::RSnapshotOptions::fMaxUnzippedClusterSize = 10 * fApproxZippedClusterSize

(RNTuple only) Maximum uncompressed cluster size

Definition at line 205 of file RSnapshotOptions.hxx.

◆ fMaxUnzippedPageSize

std::size_t ROOT::RDF::RSnapshotOptions::fMaxUnzippedPageSize = 1024 * 1024

(RNTuple only) Maximum allowed page size before compression

Definition at line 209 of file RSnapshotOptions.hxx.

◆ fMode

std::string ROOT::RDF::RSnapshotOptions::fMode = "RECREATE"

Mode of creation of output file.

Definition at line 185 of file RSnapshotOptions.hxx.

◆ fOutputFormat

ESnapshotOutputFormat ROOT::RDF::RSnapshotOptions::fOutputFormat = ESnapshotOutputFormat::kDefault

Which data format to write to.

Definition at line 186 of file RSnapshotOptions.hxx.

◆ fOverwriteIfExists

bool ROOT::RDF::RSnapshotOptions::fOverwriteIfExists = false

If fMode is "UPDATE", overwrite object in output file if it already exists.

Definition at line 190 of file RSnapshotOptions.hxx.

◆ fSplitLevel

int ROOT::RDF::RSnapshotOptions::fSplitLevel = 99

(TTree only) Split level of output tree

Definition at line 197 of file RSnapshotOptions.hxx.

◆ fVector2RVec

bool ROOT::RDF::RSnapshotOptions::fVector2RVec = true

If set to true will convert std::vector columns to RVec when saving to disk.

Definition at line 191 of file RSnapshotOptions.hxx.

The documentation for this struct was generated from the following file:

tree/dataframe/inc/ROOT/RSnapshotOptions.hxx

Public Types

Public Member Functions

Public Attributes