aggfuncs

Documentation

Index

• type AggFunc
• type PartialResult
• type SlidingWindowAggFunc

Types

type AggFunc

type AggFunc interface {
	// AllocPartialResult allocates a specific data structure to store the
	// partial result, initializes it, and converts it to PartialResult to
	// return back. The second returned value is the memDelta used to trace
	// memory usage. Aggregate operator implementation, no matter it's a hash
	// or stream, should hold this allocated PartialResult for the further
	// operations like: "ResetPartialResult", "UpdatePartialResult".
	AllocPartialResult() (pr PartialResult, memDelta int64)

	// ResetPartialResult resets the partial result to the original state for a
	// specific aggregate function. It converts the input PartialResult to the
	// specific data structure which stores the partial result and then reset
	// every field to the proper original state.
	ResetPartialResult(pr PartialResult)

	// UpdatePartialResult updates the specific partial result for an aggregate
	// function using the input rows which all belonging to the same data group.
	// It converts the PartialResult to the specific data structure which stores
	// the partial result and then iterates on the input rows and update that
	// partial result according to the functionality and the state of the
	// aggregate function. The returned value is the memDelta used to trace memory
	// usage.
	UpdatePartialResult(sctx causetnetctx.Context, rowsInGroup []chunk.Row, pr PartialResult) (memDelta int64, err error)

	// MergePartialResult will be called in the final phase when parallelly
	// executing. It converts the PartialResult `src`, `dst` to the same specific
	// data structure which stores the partial results, and then evaluate the
	// final result using the partial results as input values. The returned value
	// is the memDelta used to trace memory usage.
	MergePartialResult(sctx causetnetctx.Context, src, dst PartialResult) (memDelta int64, err error)

	// AppendFinalResult2Chunk finalizes the partial result and append the
	// final result to the input chunk. Like other operations, it converts the
	// input PartialResult to the specific data structure which stores the
	// partial result and then calculates the final result and append that
	// final result to the chunk provided.
	AppendFinalResult2Chunk(sctx causetnetctx.Context, pr PartialResult, chk *chunk.Chunk) error
}

AggFunc is the interface to evaluate the aggregate functions.

type PartialResult

type PartialResult unsafe.Pointer

PartialResult represents data structure to store the partial result for the aggregate functions. Here we use unsafe.Pointer to allow the partial result to be any type.

type SlidingWindowAggFunc

type SlidingWindowAggFunc interface {
	// Slide evaluates the aggregate functions using a sliding window. The input
	// lastStart and lastEnd are the interval of the former sliding window,
	// shiftStart, shiftEnd mean the sliding window offset. Note that the input
	// PartialResult stores the intermediate result which will be used in the next
	// sliding window, ensure call ResetPartialResult after a frame are evaluated
	// completely.
	Slide(sctx causetnetctx.Context, rows []chunk.Row, lastStart, lastEnd uint64, shiftStart, shiftEnd uint64, pr PartialResult) error
}

SlidingWindowAggFunc is the interface to evaluate the aggregate functions using sliding window.