Collaboration diagram for duckdb::TemporaryFileCompressionAdaptivity:

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Public Member Functions
TemporaryCompressionLevel	GetCompressionLevel ()
	Get the compression level to use based on current write times.

void	Update (TemporaryCompressionLevel level, int64_t time_before_ns)
	Update write time for given compression level.

Static Public Member Functions
static int64_t	GetCurrentTimeNanos ()
	Get current time in nanoseconds to measure write times.

Static Private Member Functions
static TemporaryCompressionLevel	IndexToLevel (idx_t index)
	Convert from level to index into write time array and back.

static idx_t	LevelToIndex (TemporaryCompressionLevel level)

static TemporaryCompressionLevel	MinimumCompressionLevel ()
	Min/max compression levels.

static TemporaryCompressionLevel	MaximumCompressionLevel ()

Private Attributes
RandomEngine	random_engine
	Random engine to (sometimes) randomize compression.

int64_t	last_uncompressed_write_ns
	Duration of the last uncompressed write.

int64_t	last_compressed_writes_ns [LEVELS]
	Duration of the last compressed writes.

Static Private Attributes
static constexpr int64_t	INITIAL_NS = 50000
	The value to initialize the atomic write counters to.

static constexpr idx_t	LEVELS = 6
	How many compression levels we adapt between.

static constexpr double	DURATION_RATIO_THRESHOLD = 2.0
	Bias towards compressed writes: we only choose uncompressed if it is more than 2x faster than compressed.

static constexpr double	COMPRESSION_DEVIATION = 0.5
	Probability to deviate from the current best write behavior (1 in 20)

static constexpr int64_t	WEIGHT = 16
	Weight to use for moving weighted average.

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

Public Member Functions

Static Public Member Functions