What to look for in query profiles

Profile data can show data skew, when some nodes are processing more data than others. The rows produced counter in the system table EXECUTION_ENGINE_PROFILES shows how many rows have been processed by each operator. Comparing the rows produced across all nodes for a given operator reveals if there is a data skew issue.

Note: Some profiling operators in EXECUTION_ENGINE_PROFILES are generic, such as JOIN. The EXPLAIN-generated query plan includes more details about the specific join that is executing.