I have certain expressions used by multiple steps in Azure Data Factory.
For instance, I get the start time of a pipeline often:
@formatDateTime(pipeline().TriggerTime, 'yyyy-MM-dd HH:mm:ss.fff')
If I need to change it for some reason, I'd need to update it everywhere.
I know about global parameters; however, is there a way to create global expressions?
Based on my knowledge, currently there is no way to have a global expression similar to Global parameters. For you have to have a common source of truth or 1 common expression, I would suggest you to create a common pipeline in the ADF and call that pipeline via execute pipeline activity to avoid re writing the same code every where.
You could add a variable to the pipeline and set it to the appropriate value at the start of your pipeline run: https://docs.microsoft.com/en-us/azure/data-factory/control-flow-set-variable-activity
You can then refer to this variable as you do with parameters or change its value on the go.