Performance

Quarry is a query builder. It does not add its own performance layer on top of ClickHouse.

That means Quarry does not:

• optimize your schema
• rewrite queries for speed
• infer PREWHERE
• decide when FINAL is appropriate
• choose insert batch sizes for you
• tune server settings automatically

Quarry mostly gives you typed access to the SQL features ClickHouse already has.

What this means in practice

For performance work, use the same judgment you would use with handwritten ClickHouse SQL.

Typical ClickHouse performance concerns still apply:

• schema design
• partitioning and sort keys
• filtering strategy, including PREWHERE vs WHERE
• whether FINAL is necessary
• aggregation memory use, including functions such as groupArray(...)
• insert batch sizing
• query settings such as max_threads

Quarry's role

Quarry can help you inspect the final SQL with toSQL(), but it does not try to be an optimizer.

const compiled = db
  .selectFrom("event_logs as e")
  .select("e.user_id")
  .where("e.event_type", "=", "signup")
  .toSQL();

If performance matters, inspect the SQL Quarry produced and then apply normal ClickHouse performance analysis to that query.