Performance Schema Summary Tables Aggregated statistics for executions of the prepared statement. The statement summary tables have these indexes: • events_transactions_summary_by_account_by_event_name : •Primary key on ( USER ,  HOST ,  EVENT_NAME ) • events_statements_summary_by_digest : •Primary key on ( SCHEMA_NAME ,  DIGEST ) • events_transactions_summary_by_host_by_event_name : •Primary key on ( HOST ,  EVENT_NAME ) • events_statements_summary_by_program : •Primary key on ( OBJECT_TYPE ,  OBJECT_SCHEMA ,  OBJECT_NAME ) • events_statements_summary_by_thread_by_event_name : •Primary key on ( THREAD_ID ,  EVENT_NAME ) • events_transactions_summary_by_user_by_event_name : •Primary key on ( USER ,  EVENT_NAME ) • events_statements_summary_global_by_event_name : •Primary key on ( EVENT_NAME ) •For  events_statements_summary_by_digest , it removes the rows. •For other summary tables not aggregated by account, host, or user, truncation resets the summary columns to zero rather than removing rows. TRUNCATE TABLE  is permitted for statement summary tables. It has these effects: •For other summary tables aggregated by account, host, or user, truncation removes rows for accounts, hosts, or users with no connections, and resets the summary columns to zero for the remaining rows. In addition, each statement summary table that is aggregated by account, host, user, or thread is implicitly truncated by truncation of the connection table on which it depends, or truncation of events_statements_summary_global_by_event_name . For details, see Section 27.12.8, “Performance Schema Connection Tables” . In addition, truncating  events_statements_summary_by_digest  implicitly truncates  events_statements_histogram_by_digest , and truncating events_statements_summary_global_by_event_name  implicitly truncates events_statements_histogram_global . If the  statements_digest  consumer is enabled, aggregation into events_statements_summary_by_digest  occurs as follows when a statement completes. Aggregation is based on the  DIGEST  value computed for the statement. Statement Digest Aggregation Rules 5057