Sampling Strategies

Some sources are tiny; others hold billions of rows or millions of files. Sampling is how you tell Classifyre how much of a source to read on each scan, and which items to prioritise. It’s the single most important setting for keeping scans fast, affordable, and useful — so it’s mandatory for every source.

The four strategies at a glance

If you’re unsure, leave it on Automatic — it’s designed to be the right default for almost everything.

Automatic — the recommended default

Automatic sampling gives you complete coverage without paying to read the whole source every time. Each run ingests a fresh slice of items it hasn’t seen yet, remembers its position, and picks up from there next time. Once it has been all the way through, it wraps back to the start and goes again.

• Bounded cost per run — every scan reads roughly one slice, so time and spend stay predictable no matter how big the source is.
• Eventually everything — keep scanning (ideally on a schedule) and the whole source gets covered, then refreshed on the next lap.
• Remembers its place — progress is saved between runs, so no item is repeatedly read while others are ignored.

This pairs naturally with a recurring schedule: a little, often, until it all gets seen — then around again to catch changes.

Latest — freshest first

Latest sampling prioritises the most recently created or modified items. Use it when new data is the data that matters — recent uploads, the newest records, this week’s documents.

For tabular sources (databases, warehouses), Classifyre orders by a date-like column:

• It auto-detects a sensible column (typically something like created_at or updated_at).
• You can name the column explicitly if you’d rather choose.
• If no ordering column can be found, it can fall back to Random so the scan still produces a useful sample rather than failing.

Random — a representative spot-check

Random sampling reads a random subset of items. It’s the quickest way to get a representative feel for what’s in a large source — great for an initial assessment, a quality spot-check, or estimating how prevalent an issue is before committing to fuller coverage.

All — complete coverage in one pass

All reads every item, with no limit. Choose it when the source is small enough to scan completely, or when you genuinely need exhaustive coverage in a single run (for example, a compliance sweep that must touch everything at once).

All is the most thorough strategy and also the most expensive — it reads everything, every scan. For large sources, Automatic usually gets you the same total coverage at a fraction of the per-run cost.

The controls

A few settings shape how a strategy behaves. The most useful one applies to tabular sources (databases and warehouses):

For non-tabular sources (files, messages, videos), the strategy controls which items are read; there’s no rows-per-page to set.

Choosing the right strategy

Next: let scans see more than plain text with OCR & Transcription.