Module table_sample 

The sample as a step of the view: drawn into memory a chunk at a time, while the table shows the rows kept so far.

draw reads the rows crate::sampling would, but hands each chunk that is final when kept to SampleRows as it lands: a seeded run of one Parquet or IPC file, a batch of the head or of every row, and a batch’s share of a Bernoulli sample when the total is known. A reservoir (an unknown total) and an equal per value sample keep evicting rows until the end, so their rows arrive as one chunk when the read ends. Rows land in arrival order; SampleRows::in_source_order puts them in the order the source holds them once the draw ends.

Nothing is written to disk: saving a sample is export’s job.

Structs

Drawn

What a draw read, beside the rows it kept.

Live

What a draw keeps its chunks in and how it says so.

MemoryCheck

The memory a draw is checked against, before it starts and as it runs.

SampleRows

The chunks a draw has kept, shared between its worker and the view that shows them. The data is held once: the view’s frame is built on these chunks.

Enums

DrawPath

How a random sample of a stream was drawn: what makes the same seed draw the same rows again, so a view keeps it and a redraw takes it again.

Limit

Where the memory a draw may take is measured against.

Constants

MEMORY_SETTING

The setting that caps a sample’s memory, as every message about it names it.

Functions

available_memory

The memory available now, as the system (or the cgroup it runs in) says.

draw

Draw sample from lf, already cut to its scope, into live’s chunks.

Type Aliases

MemoryProbe

Reads the memory available now, in bytes; None when the system will not say.