ClickHouse Production Checklist

The ORDER BY of each large table matches its actual query filters, verified with EXPLAIN indexes = 1.

Low-cardinality columns come before high-cardinality ones in the sorting key.

String columns with a bounded value set use LowCardinality.

Codecs are set on columns where they help (Delta for monotonic values, ZSTD for large text).

Partition count per table is in the tens or low hundreds — not partitioned by a high-cardinality column.

Every table uses a Replicated engine if the cluster has more than one replica.