Hello @sharat_n ,
Yes, it is generally safe to run a DELETE query on a Delta Lake table while active writes are happening.
Delta Lake is designed with ACID transactions, meaning operations like DELETE, UPDATE, and MERGE are atomic and isolated.
In other words, the transactions will happen independently, one after the other - and either the transaction succeed or it will be rolled back as a whole transaction.
You can find out more about ACID guarantees here:
https://docs.databricks.com/en/lakehouse/acid.html
Regarding Your next question - it is generally safe to run vacuum as no active transactions are happening to the delta table.
You should be careful with setting the retention period (recommended at least 7 days [default] or more).
In docs we can find, that "If VACUUM cleans up active files, concurrent readers can fail or, worse, tables can be corrupted when VACUUM deletes files that have not yet been committed. You must choose an interval that is longer than the longest running concurrent transaction and the longest period that any stream can lag behind the most recent update to the table."
Find out more about VACUUM here:
https://docs.databricks.com/en/sql/language-manual/delta-vacuum.html
Best,
Rado.
