thanos-io/thanos · error

aggregate does not exist

Error message

aggregate %s does not exist

What it means

When serving a downsampled series, the store unpacks an AggrChunk and fetches each requested aggregate sub-chunk. This error means the AggrChunk container does not carry the COUNT aggregate the caller asked for, so the aggregate cannot be returned. AggrChunk sub-chunks are optional; older or partially written downsampled data may omit some.

Solutions

1. Verify the downsampled blocks in the bucket actually contain count chunks (thanos tools bucket inspect).
2. Regenerate downsampled blocks with the compactor so all requested aggregates exist.
3. Remove COUNT from the requested aggregates (storepb.Aggr_COUNT) for this store view / query path.
4. Check the store API client's requested_aggs against what the block resolution provides.

Example fix

// client side: request only aggregates the data provides
aggs := []storepb.Aggr{storepb.Aggr_SUM, storepb.Aggr_MIN, storepb.Aggr_MAX}
// instead of unconditionally including storepb.Aggr_COUNT

// client-side: request only aggregates known to exist for the block resolution
aggrs := availableAggregatesForResolution(blockMeta.Resolution) // exclude COUNT if unavailable

resp, err := client.Series(ctx, req)
if err != nil && strings.Contains(err.Error(), "aggregate count does not exist") {
    req.Aggregates = removeAggr(req.Aggregates, storepb.Aggr_COUNT)
    resp, err = client.Series(ctx, req)
}

When it happens

Trigger: A Series request with Aggr_COUNT in the requested aggregates, where ac.Get(downsample.AggrCount) returns an error because the AggrChunk's count sub-slot is empty (unset sample count / empty encoding).

Common situations: Downsampled blocks produced by older Thanos versions before all aggregates were stored; queries for COUNT against data where only some aggregates were computed; aggregation bitmask in the store API requesting aggregates the block lacks.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• raw resolution must be higher than the minimum block size…
• 5m resolution retention must be higher than the minimum…
• sync before first pass of downsampling
• first pass of downsampling failed
• sync before second pass of downsampling

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/13b819685c66f462. Report an issue: GitHub.

Appendix: source

Thrown at pkg/store/bucket.go:1438

			Data: b,
			Type: chunkToStoreEncoding(in.Encoding()),
			Hash: hashChunk(hasher, b, calculateChecksum),
		}
		return nil
	}

	if in.Encoding() != downsample.ChunkEncAggr {
		return errors.Errorf("unsupported chunk encoding %d", in.Encoding())
	}

	ac := downsample.AggrChunk(in.Bytes())

	for _, at := range aggrs {
		switch at {
		case storepb.Aggr_COUNT:
			x, err := ac.Get(downsample.AggrCount)
			if err != nil {
				return errors.Errorf("aggregate %s does not exist", downsample.AggrCount)
			}
			b, err := save(x.Bytes())
			if err != nil {
				return err
			}
			out.Count = &storepb.Chunk{Type: chunkToStoreEncoding(x.Encoding()), Data: b, Hash: hashChunk(hasher, b, calculateChecksum)}
		case storepb.Aggr_SUM:
			x, err := ac.Get(downsample.AggrSum)
			if err != nil {
				return errors.Errorf("aggregate %s does not exist", downsample.AggrSum)
			}
			b, err := save(x.Bytes())
			if err != nil {
				return err
			}
			out.Sum = &storepb.Chunk{Type: chunkToStoreEncoding(x.Encoding()), Data: b, Hash: hashChunk(hasher, b, calculateChecksum)}
		case storepb.Aggr_MIN:
			x, err := ac.Get(downsample.AggrMin)

View on GitHub (pinned to 35b8b99117)