Module schema 

On-disk Arrow schemas. These follow the OTAP star schema (otap-spec.md sections 5.4 and 6.3) rather than a flattened one-row-per-span layout: a root table per signal carrying resource_id/scope_id foreign keys, plus entity-attribute-value side tables keyed by parent_id.

Two deliberate deviations from the OTAP wire spec, both documented in docs/architecture.md:

• parent_id and the root id are UInt32 and block-local. On the wire OTAP ids are only unique within one BatchArrowRecords; persisting them verbatim and joining across batches silently produces a cross product. We rebase to a dense per-block id at ingest, so a join inside a block is unconditionally correct and needs no partition discriminant column.
• Attribute values are plain, not dictionary-encoded. Dictionary encoding is a low-cardinality technique with a hard ceiling (DictionaryKeyOverflow at 2^16 for UInt16 keys); attribute values are the highest-cardinality data in the system. Only enumerable columns (attribute keys, severity text) are dictionaries.

Enums

AttrType

OTAP attribute value discriminant (type column). Matches otap-spec.md 5.4.

MetricKind

Which Metric.data variant a descriptor row carries.

Constants

DICT_CAP

How many distinct values a UInt16 dictionary can hold. Lives here because it is a consequence of the key width chosen above, not of any one builder. Reaching it is a signal to seal the block, never to fail an export.

LOGS_BLOCK_TABLES

The tables a logs block is made of, in publish order.

METRICS_BLOCK_TABLES

The tables a metrics block is made of, in publish order.

TRACES_BLOCK_TABLES

The tables a traces block is made of, in publish order.

Statics

ATTRS

Shared shape for LOG_ATTRS / RESOURCE_ATTRS / SCOPE_ATTRS.

EXEMPLARS

EXEMPLARS — the bridge from a metric point to the trace that produced it.

EXP_HIST_DP

EXP_HIST_DP — exponential histogram points.

HIST_BOUNDS

HIST_BOUNDS — the interned explicit_bounds arrays of this block.

HIST_DP

HIST_DP — explicit-bucket histogram points.

LOGS

LOGS root table.

METRICS

METRICS descriptor table — one row per Metric message, not per point.

NUMBER_DP

NUMBER_DP — gauge and sum points.

RESOURCES

RESOURCES table — one row per distinct resource in the block.

SPANS

SPANS root table.

SPAN_EVENTS

SPAN_EVENTS — a child table, not a List<Struct> column.

SPAN_LINKS

SPAN_LINKS — same child-table reasoning as SPAN_EVENTS.

SUMMARY_DP

SUMMARY_DP — the legacy quantile representation, kept because OTLP still carries it out of Prometheus.

Functions

dict_u16_utf8 🔒

dict_u32_utf8 🔒

A dictionary wide enough that a block cannot fill it.

dp_head 🔒

Columns every data point table has, in the same order, so that a temporal filter is the same code against any of the four.

list_of 🔒

ts 🔒