The number of joins without keys that check for key usage after each row. If this is not 0, you should carefully check the indexes of your tables. 

• Select_scan 

The number of joins that did a full scan of the first table. 

• Slave_open_temp_tables 

The number of temporary tables that the replication SQL thread currently has open. If the value is greater than zero, it is not safe to shut down the replica; see Section 17.5.1.31, “Replication and Temporary Tables” . This variable reports the total count of open temporary tables for all  replication channels. 

• Slave_rows_last_search_algorithm_used 

The search algorithm that was most recently used by this replica to locate rows for row-based replication. The result shows whether the replica used indexes, a table scan, or hashing as the search algorithm for the last transaction executed on any channel. 

The method used depends on the setting for the slave_rows_search_algorithms  system variable, and the keys that are available on the relevant table. 

This variable is available only for debug builds of MySQL. 

• Slow_launch_threads 

The number of threads that have taken more than slow_launch_time  seconds to create. 

• Slow_queries 

The number of queries that have taken more than long_query_time  seconds. This counter increments regardless of whether the slow query log is enabled. For information about that log, see Section 5.4.5, “The Slow Query Log” . 

• Sort_merge_passes 

The number of merge passes that the sort algorithm has had to do. If this value is large, you should consider increasing the value of the sort_buffer_size  system variable. 

• Sort_range 

The number of sorts that were done using ranges. 

• Sort_rows 

The number of sorted rows. 

• Sort_scan 

The number of sorts that were done by scanning the table. 

• Ssl_accept_renegotiates 

The number of negotiates needed to establish the connection. 

• Ssl_accepts 

