BigQuery Best Practices: Avoid SELECT *
BigQuery is a columnar database. Using SELECT * is the most expensive way to query data. When you use SELECT *, BigQuery does a full scan of every column in the table.
Instead, Query only the columns that are required. BigQuery will only fetch the specified columns and it will comparatively faster and cheaper
select * from employee
can be rewritten as
select id, name from employee
Tip: Columnar databases can pick the required columns alone are very efficient at processing column level aggregations. So, avoid SELECT * when possible