Question

How to perform a dry run of a query so as to get a cost estimate of the query beforehand? How can I do this using command line?

Answer 1

To perform a dry run:

Enter a query like the following using the --dry_run flag.

bq query \
--use_legacy_sql=false \
--dry_run \
'SELECT
   COUNTRY,
   AIRPORT,
   IATA
 FROM
   `project_id`.dataset.airports
 LIMIT
   1000'

The command produces the following response:

Query successfully validated. Assuming the tables are not modified,
running this query will process 10918 bytes of data.