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DROP TABLE IF EXISTS t1;
CREATE TABLE t1 (a INT, INDEX (a));
INSERT INTO t1 VALUES (),(),(),(),(),(),(),(),(),();
FLUSH STATUS;
SELECT a FROM t1 ORDER BY a LIMIT 1;
a
NULL
SHOW STATUS LIKE 'HANDLER_READ%';
Variable_name Value
Handler_read_first 1
Handler_read_key 0
Handler_read_last 0
Handler_read_next 0
Handler_read_prev 0
Handler_read_retry 0
Handler_read_rnd 0
Handler_read_rnd_deleted 0
Handler_read_rnd_next 0
FLUSH STATUS;
SELECT a FROM t1 ORDER BY a DESC LIMIT 1;
a
NULL
SHOW STATUS LIKE 'HANDLER_READ%';
Variable_name Value
Handler_read_first 0
Handler_read_key 0
Handler_read_last 1
Handler_read_next 0
Handler_read_prev 0
Handler_read_retry 0
Handler_read_rnd 0
Handler_read_rnd_deleted 0
Handler_read_rnd_next 0
FLUSH STATUS;
SELECT a FROM t1 ORDER BY a LIMIT 3;
a
NULL
NULL
NULL
SHOW STATUS LIKE 'HANDLER_READ%';
Variable_name Value
Handler_read_first 1
Handler_read_key 0
Handler_read_last 0
Handler_read_next 2
Handler_read_prev 0
Handler_read_retry 0
Handler_read_rnd 0
Handler_read_rnd_deleted 0
Handler_read_rnd_next 0
FLUSH STATUS;
SELECT a FROM t1 ORDER BY a DESC LIMIT 3;
a
NULL
NULL
NULL
SHOW STATUS LIKE 'HANDLER_READ%';
Variable_name Value
Handler_read_first 0
Handler_read_key 0
Handler_read_last 1
Handler_read_next 0
Handler_read_prev 2
Handler_read_retry 0
Handler_read_rnd 0
Handler_read_rnd_deleted 0
Handler_read_rnd_next 0
DROP TABLE t1;
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