Query hints

Firebolt supports the use of query hints, which are special comments embedded in your SQL statements. These hints allow you to influence the behavior of the query planner, giving you greater control over how your queries are executed. Query hints are comments that start with /*! and end with */. The following example demonstrates the syntax using the hint no_partial_agg:

SQL source

explain(physical)
select /*! no_partial_agg */
  AVG(quantity),
  location_id
from
  fact_sales
group by
  location_id;

Supported hints in Firebolt

No partial aggregation. Disable partial aggregation for group by queries.
No join ordering. Disable join order optimization and instead use the order of the tables in the query.
Optimize for single row window partitions. Optimize window expressions for high cardinality partitions.
Unique columns. Specify that columns contain unique values to improve query optimization.

UNIQUE constraints as query hints

No partial aggregation

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Supported hints in Firebolt

​Supported hints in Firebolt

Supported hints in Firebolt