JSON schema filter distribution groups by Dynamic attribute paths

[mfroembgen]

Summary

With ClickStack/HyperDX JSON schema mode enabled, filter value/distribution queries can fail for JSON-backed OTel attribute paths because HyperDX emits untyped JSON path expressions and then groups/aggregates over them.

Example error

Data types Variant/Dynamic are not allowed in GROUP BY keys

Example generated query shape

SELECT ResourceAttributes.k8s.namespace.name AS __hdx_value, count() AS __hdx_count
FROM default.otel_logs
GROUP BY __hdx_value

In ClickHouse, that path is Dynamic(max_types=8), so grouping fails. A typed JSON path works instead:

ResourceAttributes.`k8s`.`namespace`.`name`.:String

A related key-values query can also fail when map-style access is used against a JSON column:

ResourceAttributes['k8s.namespace.name']

Environment

• HyperDX 2.28.0
• ClickHouse 26.5.1.882
• BETA_CH_OTEL_JSON_SCHEMA_ENABLED=true
• HYPERDX_OTEL_EXPORTER_CLICKHOUSE_JSON_ENABLE=true
• otel_logs.ResourceAttributes is JSON(max_dynamic_types=8, max_dynamic_paths=64)

Upstream main appears to still pass raw key expressions into metadata/filter queries such as getValuesDistribution / getKeyValues.

Expected

For JSON attribute columns, HyperDX should render typed JSON subcolumn expressions, or otherwise cast to a stable type, before using them in GROUP BY, groupUniqArray, etc. Map columns should keep the existing bracket syntax.

I'd be open to contributing a fix if maintainers agree with this direction.

[mfroembgen]

Follow-up from #2551: I tested this against ClickHouse directly and adjusted the fix to avoid relying on a fixed .:String JSON subcolumn suffix.

The verified ClickHouse version is 26.5.1.882, with both ResourceAttributes and LogAttributes represented as JSON(max_dynamic_types=8, max_dynamic_paths=64). Live queries showed toString(<JSON path>) returns usable values for string (ResourceAttributes.k8s.namespace.name), integer (ResourceAttributes.cloud.account.id), boolean (LogAttributes.endOfBatch), and mixed-type (LogAttributes.level) paths, while fixed .:String can miss non-string dynamic paths. Distribution/grouping queries using toString(...) also worked on the same data shape.

PR #2551 now renders JSON sidebar and metadata value/distribution expressions with toString(...), and has been re-tested with focused unit tests plus the full filter-key-edge-cases e2e spec.