Hi @Vladimir Ryabtsev​ 

Need some more info

1. Can you get the total size & number of records the of delta table you have ?
2. "full scan of which takes ~20 minutes on my cluster" - are you using the same cluster for query and if yes, the screenshot of that full scan too.
3. For the DAG, after you click on Job details in the spark UI, you will find a highlighted id for the associated SQL query at the top. Click on that id, expand all the details in the query plan visualization and kindly paste it here.

To find the size of a delta table, you can use a Apache Spark SQL command.

import com.databricks.sql.transaction.tahoe._

val deltaLog = DeltaLog.forTable(spark, "dbfs:/<path-to-delta-table>")

val snapshot = deltaLog.snapshot        // the current delta table snapshot

println(s"Total file size (bytes): ${deltaLog.snapshot.sizeInBytes}")