name: data-querying description: Write and verify SQL queries with BigQuery. Use when executing bq commands, writing SQL queries, or including query results in documents.
Data Querying
Verification Requirement
All queries MUST be executed with bq and verified before inclusion. Never include unverified queries or fabricated data.
Query Process
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Dry run: Validate syntax and check cost
bq query --project_id=<PROJECT_ID> --use_legacy_sql=false --dry_run "SELECT ..."Cost: ~$5/TB. <1GB is light, 2GB+ needs optimization.
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Execute: Run and confirm results
bq query --project_id=<PROJECT_ID> --use_legacy_sql=false --format=csv "SELECT ..." -
Learn: Study existing queries in project docs for patterns.
Query Design
- Specify exact date ranges
- Filter partitioned tables by partition key
- Avoid correlated subqueries (use JOINs/CTEs)
- Filter early with CTEs before joining large tables
Documentation
- Execute exact query with
bq - Copy real output only
- State time period and what query measures