Partitioned tables in BigQuery include a pseudo column named _PARTITIONTIME that contains a date-based timestamp for data loaded into the table. To query specific partitions, such as January 1st and 2nd of 2017, you can use a clause like this: WHERE _PARTITIONTIME BETWEEN TIMESTAMP('2017-01-01') AND TIMESTAMP('2017-01-02'). This method efficiently limits your query to the specified partitions. For more details, refer to the BigQuery documentation on partitioned tables.