Optional ClickHouse analytics sink for Ponder

[neuroborus]

Problem

We use Ponder in production for its intended purpose. With millions of rows we hit Postgres limits quickly. Even with indexes, analytical queries became slow and resource heavy.

This is expected. General purpose relational databases are not optimized for high volume timeseries workloads, especially on very large tables. Postgres stays the right choice for Ponder's canonical state, but it is not the best tool for wide, append heavy analytical reads.

Proposal

Add ClickHouse as an optional analytics database. Postgres remains canonical for application data, checkpoints, migrations, reorg recovery, and the query APIs. ClickHouse receives an append only projection of indexed events for analytical queries.

Properties:

• Opt in. A project without a sink has no ClickHouse dependency, process, or changed runtime behavior.
• Backward compatible. Existing config, public types, and defaults are unchanged.
• Package scoped. The ClickHouse client, DDL, and credentials live in @ponder/clickhouse. Core exposes only a vendor neutral sink contract.

How it is split

I opened six pull requests that build on each other and preserve backward compatibility at every step.

The first four are a minimal integration: only finalized events are written to ClickHouse, so there is no reorg handling and no provisional data.

The last two are the next level: opt in live delivery with append only reorg revocations, on a separate v2 table.

PR	Branch	Scope
1	feat/ch1-finalized-sink-delivery	Generic durable sink contract and Postgres outbox in core.
2	feat/ch2-clickhouse-analytics-sink	@ponder/clickhouse package for finalized events.
3	test/ch3-clickhouse-acceptance	Real ClickHouse acceptance coverage in CI.
4	docs/ch4-clickhouse-sink	Docs, runnable example, and changeset.
5	feat/ch5a-core-live-sink	Optional live and reorg hooks in the core contract.
6	feat/ch5b-clickhouse-live-reorg	ClickHouse live rows and append only reorg markers.

PRs 1 to 4 are finalized only. PRs 5 and 6 add live and reorg delivery. Each PR builds and tests independently and can be reviewed on its own.