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.