Runs multiple BigQuery query jobs in parallel, demonstrating an improvement in performance when compared to running the jobs serially, one after the other.

## Explore further


For detailed documentation that includes this code sample, see the following:

- [Run multiple BigQuery jobs in parallel](https://docs.cloud.google.com/workflows/docs/tutorials/bigquery-parallel-jobs)

## Code sample

### YAML

    main:
        steps:
        - init:
            assign:
                - results : {} # result from each iteration keyed by table name
                - tables:
                    - 201201h
                    - 201202h
                    - 201203h
                    - 201204h
                    - 201205h
        - runQueries:
            parallel:
                shared: [results]
                for:
                    value: table
                    in: ${tables}
                    steps:
                    - logTable:
                        call: sys.log
                        args:
                            text: ${"Running query for table " + table}
                    - runQuery:
                        call: googleapis.bigquery.v2.jobs.query
                        args:
                            projectId: ${sys.get_env("GOOGLE_CLOUD_PROJECT_ID")}
                            body:
                                useLegacySql: false
                                useQueryCache: false
                                timeoutMs: 30000
                                # Find top 100 titles with most views on Wikipedia
                                query: ${
                                    "SELECT TITLE, SUM(views)
                                    FROM `bigquery-samples.wikipedia_pageviews." + table + "`
                                    WHERE LENGTH(TITLE) > 10
                                    GROUP BY TITLE
                                    ORDER BY SUM(VIEWS) DESC
                                    LIMIT 100"
                                    }
                        result: queryResult
                    - returnResult:
                        assign:
                            # Return the top title from each table
                            - results[table]: {}
                            - results[table].title: ${queryResult.rows[0].f[0].v}
                            - results[table].views: ${queryResult.rows[0].f[1].v}
        - returnResults:
            return: ${results}

## What's next


To search and filter code samples for other Google Cloud products, see the
[Google Cloud sample browser](https://docs.cloud.google.com/docs/samples?product=workflows).