Server Status Variables 955 A counter for the prepare phase of two-phase commit operations. The number of times the first entry in an index was read. If this value is high, it suggests that the server is doing a lot of full index scans (for example,  SELECT col1 FROM foo , assuming that  col1  is indexed). The number of requests to read a row based on a key. If this value is high, it is a good indication that your tables are properly indexed for your queries. The number of requests to read the last key in an index. With  ORDER BY , the server issues a first-key request followed by several next-key requests, whereas with  ORDER BY DESC , the server issues a last- key request followed by several previous-key requests. The number of requests to read the next row in key order. This value is incremented if you are querying an index column with a range constraint or if you are doing an index scan. The number of requests to read the previous row in key order. This read method is mainly used to optimize  ORDER BY ... DESC . The number of requests to read a row based on a fixed position. This value is high if you are doing a lot of queries that require sorting of the result. You probably have a lot of queries that require MySQL to scan entire tables or you have joins that do not use keys properly. The number of requests to read the next row in the data file. This value is high if you are doing a lot of table scans. Generally this suggests that your tables are not properly indexed or that your queries are not written to take advantage of the indexes you have. The number of requests for a storage engine to perform a rollback operation. The number of requests for a storage engine to place a savepoint. The number of requests for a storage engine to roll back to a savepoint. The number of requests to update a row in a table. • Handler_prepare • Handler_read_first • Handler_read_key • Handler_read_last • Handler_read_next • Handler_read_prev • Handler_read_rnd • Handler_read_rnd_next • Handler_rollback • Handler_savepoint • Handler_savepoint_rollback • Handler_update • Handler_write