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Re: How do you branch your code with BigQuery?


Awesome!
I think this would be a fine addition to the BigQuery operators if you ever think about PR this to airflow master

cheers

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‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Monday, October 15, 2018 10:02 AM, Anthony Brown <anthony.brown@xxxxxxxxxxxxxxx> wrote:

> Hi
> I have created a custom plugin that allows you to branch on the results
> of a BigQuery query. The code for it is at
> https://github.com/JohnLewisandPartners/custom-airflow-plugins/blob/master/bq_branch/plugins/bq_branch.py.
> The version in master only works on airflow 1.10, but there is a branch
> called airflow_1.9 that also contains the latest BigQuery hook and so works
> on airflow 1.9
>
> The query you run must return true for all columns - the same as for the
> BigQuery check operator, so you may need to rewrite your queries to do this
>
> On Sun, 14 Oct 2018 at 14:16, airflowuser
> airflowuser@xxxxxxxxxxxxxx.invalid wrote:
>
> > I believe this is quite common case when working with data.
> > If something : do A
> > else: do B
> > With coding PythonBranchOperator is the solution.
> > But when working on Google Cloud there is no way to do this.
> > All existed operators are designed to continue or fail on comparison of
> > specific value:
> > BigQueryValueCheckOperator with pass_value=500 will continue if 500
> > return or fail in any other case. Same for all other CheckOperators. You
> > must know the value in advanced for this to work and it's not an actual
> > branch but more of a way to stop the workflow if an unexpected result has
> > been found.
> > But how do you handle a scenario where you want to do A or B based on
> > condition from a query result? Nothing needs to be failed. just a simple
> > branch.
> > XCOM could solve it. But there is no support for XCOM yet.
> > https://stackoverflow.com/questions/52801318/airflow-how-to-push-xcom-value-from-bigqueryoperator
> > Say for example:
> > the query represent the number of frauds.. if it's <1000 you want to email
> > specific users (EmailOperator) , if it's >=1000 you want to run another
> > operator and continue the workflow.
> > Any thoughts on the matter will be appreciated.
>
> --
>
> --
>
> Anthony Brown
> Data Engineer BI Team - John Lewis
> Tel : 0787 215 7305
>
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