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Data & Analytics · Intermediate

Partition Pruning

Skipping partitions whose data cannot satisfy a query's filter, which reduces the data scanned.

Definition

Pruning (partition elimination) relies on filters on the partition or clustering columns that the optimizer can evaluate. In BigQuery it directly lowers bytes billed, and in Snowflake it works on micro-partition min/max metadata.

Example

WHERE order_date = '2026-10-31' scans only that day's partition.

Exam tip

Wrapping the partition column in a function, or filtering on an unrelated column, can defeat pruning.

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