ClickHouse count() accepts no arguments, so the column type must be
AggregateFunction(count) not AggregateFunction(count, UInt64). The
latter causes countMerge() to fail with ILLEGAL_TYPE_OF_ARGUMENT.
Drop and recreate the table/MV to apply the corrected schema.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Pre-aggregate route execution stats into 5-minute buckets using a
materialized view with -State/-Merge combinators. Rewrite stats() and
timeseries() to query the rollup table instead of scanning the wide
base table. Active count remains a real-time query since RUNNING is
transient. Includes idempotent backfill migration.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
