Amazon Redshift
Database Developer Guide (API Version 2012-12-01)

Analyzing the Query Summary

To get execution steps and statistics in more detail than in the query plan than EXPLAIN produces, use the SVL_QUERY_SUMMARY and SVL_QUERY_REPORT system views.

SVL_QUERY_SUMMARY provides query statistics by stream. You can use the information it provides to identify issues with expensive steps, long-running steps, and steps that write to disk.

The SVL_QUERY_REPORT system view allows you to see information similar to that for SVL_QUERY_SUMMARY, only by compute node slice rather than by stream. You can use the slice-level information for detecting uneven data distribution across the cluster (also known as data distribution skew), which forces some nodes to do more work than others and impairs query performance.