Meridian Storage ClickHouse

meridian-storage-clickhouse is the independently released ClickHouse adapter for Meridian V1. It executes mapping-first, engine-neutral Operations for stored logs, spans, metric points, usage, cost, and generic analytical time-series Records. It provides deterministic schema and migration plans, bounded idempotent batch ingestion, mandatory time-bounded query pushdown, live keyset pagination, result normalization, authenticated probes, and physical fingerprints.

The distribution contributes exactly one adapter package, meridian_storage.adapters.clickhouse, and discovers through the released Meridian Core 1.1 Adapter SPI. It consumes only the released meridian-storage-core>=1.1,<2, meridian-storage-semantics>=2.0.1,<3, and meridian-storage-query>=1.0.3,<2 packages. Adapter, layout, append, and Query plan contract versions remain unchanged.

Boundary

Application code does not import this package, create a ClickHouse client, issue SQL, select a table engine, or provide an endpoint. It uses the registered evidence or structured Catalog Expression surface. The composition root starts Meridian after deployment IaC has injected an opaque Binding:

from meridian_storage import Meridian, OperationContext

meridian = Meridian.from_environment()
meridian.start()
evidence = meridian.catalog("evidence")

with meridian.context(
    OperationContext(
        principal_ref="identity:service/worker",
        tenant="tenant-a",
        scope={"workspace": "operations"},
    )
):
    result = meridian.execute(
        evidence.query(
            resource="runtime.logs",
            where={
                "event_time": {
                    "gte": "2026-08-25T00:00:00Z",
                    "lt": "2026-08-26T00:00:00Z",
                }
            },
            limit=100,
        )
    )

Collector deployment, topology, credentials, ACLs, retention, backups, restores, and migration job lifecycle remain owned by Platform or Vangu IaC through MeridianConstructs. Runtime startup only authenticates, probes compatibility, and verifies pre-provisioned physical fingerprints.

Guarantees and limits

• Writes are append-oriented and idempotent only within the advertised retry/deduplication window. The adapter does not claim general exactly-once execution.
• Every scan and aggregate requires a bounded UTC time range within the Binding limit.
• Scope isolation is injected ahead of user predicates and leads every table sort key.
• Visibility is eventual. General transactions, compare-and-set, authoritative patch, foreign keys, cross-Binding joins, and native SQL Expressions are denied.
• Decimal, timestamp, UUID, bytes, JSON, nullable, and quantile values are normalized back to Meridian wire representations. Percentiles use the exact ClickHouse quantile function in V1.

Adapter-author and IaC integration

The public adapter-author surface includes ClickHouseAdapterFactory, ClickHouseSchemaCompiler, ClickHouseMigrator, ClickHouseQueryTranslator, adapter_descriptor, capability_manifest, and plan_initial_migration. These are deployment and adapter integration contracts, not business APIs. See architecture.md, configuration.md, operations.md, migrations.md, and conformance.md.

Development

python -m venv .venv
.venv/bin/python -m pip install -e '.[test]'
.venv/bin/ruff check .
.venv/bin/mypy src
.venv/bin/pytest -m 'not integration and not cluster'
./scripts/run-standalone-conformance.sh
./scripts/run-cluster-conformance.sh

Real-engine tests use disposable ClickHouse containers and never target a deployment-owned database. See tests/integration and tests/cluster for the exact profiles.

License

Licensed under the Apache License, Version 2.0. See LICENSE and NOTICE.

Deployment-owned releases and retained gates are documented in release selection.