Bug#52312 lost Handler_read_last status variable

Before this fix, the ha_read_last_count status variable was defined and
updated internally, for never exposed as a system variable.

This fix exposes the system variable as "Handler_read_last",
for completness of the Handler_read_* system variables interface.

Adjusted tests results accordingly.

mysql-test/r/create.result

@@ -1542,6 +1542,7 @@ show status like 'handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0

mysql-test/r/handler_read_last.result

@@ -0,0 +1,60 @@
+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_rnd	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_rnd	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_rnd	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_rnd	0
+Handler_read_rnd_next	0
+DROP TABLE t1;

mysql-test/r/insert_select.result

@@ -694,6 +694,7 @@ 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_rnd	0

mysql-test/r/join.result

@@ -854,6 +854,7 @@ show status like 'Handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0

mysql-test/r/join_outer.result

@@ -1238,6 +1238,7 @@ show status like 'Handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	5
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0

mysql-test/r/null_key.result

@@ -424,6 +424,7 @@ SHOW STATUS LIKE "handler_read%";
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	6
+Handler_read_last	0
 Handler_read_next	2
 Handler_read_prev	0
 Handler_read_rnd	0

mysql-test/r/partition.result

@@ -359,6 +359,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	2
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -377,6 +378,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	2
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -407,6 +409,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	2
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -423,6 +426,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	2
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -439,6 +443,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	2
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -455,6 +460,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	2
 Handler_read_prev	0
 Handler_read_rnd	0

mysql-test/r/select.result

@@ -4338,6 +4338,7 @@ SHOW STATUS LIKE 'Handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	2
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0

mysql-test/r/single_delete_update.result

@@ -25,6 +25,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -41,6 +42,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -74,6 +76,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -90,6 +93,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	5
@@ -120,6 +124,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -136,6 +141,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	1
@@ -170,6 +176,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	1
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -186,6 +193,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	1
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -214,6 +222,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -230,6 +239,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	1
@@ -256,6 +266,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	1
@@ -272,6 +283,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	1
@@ -301,6 +313,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	2
+Handler_read_last	0
 Handler_read_next	7
 Handler_read_prev	0
 Handler_read_rnd	4
@@ -322,6 +335,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	2
+Handler_read_last	0
 Handler_read_next	7
 Handler_read_prev	0
 Handler_read_rnd	8
@@ -357,6 +371,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	4
 Handler_read_rnd	0
@@ -373,6 +388,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	4
 Handler_read_rnd	0
@@ -406,6 +422,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -422,6 +439,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	5
@@ -464,6 +482,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	1
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -486,6 +505,7 @@ 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	4
 Handler_read_rnd	0
@@ -502,6 +522,7 @@ 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	4
 Handler_read_rnd	0
@@ -536,6 +557,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -552,6 +574,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	5
@@ -590,6 +613,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -606,6 +630,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	5
@@ -641,6 +666,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -657,6 +683,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	1
@@ -691,6 +718,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	1
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -707,6 +735,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	1
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	5
@@ -735,6 +764,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -751,6 +781,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	1
@@ -778,6 +809,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	1
@@ -794,6 +826,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	1
@@ -824,6 +857,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	2
+Handler_read_last	0
 Handler_read_next	7
 Handler_read_prev	0
 Handler_read_rnd	4
@@ -845,6 +879,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	2
+Handler_read_last	0
 Handler_read_next	7
 Handler_read_prev	0
 Handler_read_rnd	8
@@ -884,6 +919,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	4
 Handler_read_rnd	0
@@ -900,6 +936,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	4
 Handler_read_rnd	5
@@ -938,6 +975,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -954,6 +992,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	5
@@ -990,6 +1029,7 @@ SHOW STATUS LIKE 'Handler_read_%';
 Variable_name	Value
 Handler_read_first	1
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	4
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -1012,6 +1052,7 @@ 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	4
 Handler_read_rnd	0
@@ -1028,6 +1069,7 @@ 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	4
 Handler_read_rnd	5

mysql-test/r/subselect3.result

@@ -113,6 +113,7 @@ show status like '%Handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0

mysql-test/r/update.result

@@ -273,6 +273,7 @@ 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_rnd	0
@@ -284,6 +285,7 @@ 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_rnd	2
@@ -294,6 +296,7 @@ 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_rnd	0
@@ -304,6 +307,7 @@ 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_rnd	0
@@ -315,6 +319,7 @@ show status like 'handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	0
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	1
@@ -368,6 +373,7 @@ show status like 'handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	1
 Handler_read_prev	0
 Handler_read_rnd	1
@@ -405,6 +411,7 @@ show status like '%Handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	1
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -415,6 +422,7 @@ show status like '%Handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	2
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -424,6 +432,7 @@ show status like '%Handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	3
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0
@@ -433,6 +442,7 @@ show status like '%Handler_read%';
 Variable_name	Value
 Handler_read_first	0
 Handler_read_key	3
+Handler_read_last	0
 Handler_read_next	0
 Handler_read_prev	0
 Handler_read_rnd	0

mysql-test/t/handler_read_last.test

@@ -0,0 +1,40 @@
+# Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# 51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+
+CREATE TABLE t1 (a INT, INDEX (a));
+INSERT INTO t1 VALUES (),(),(),(),(),(),(),(),(),();
+
+FLUSH STATUS;
+SELECT a FROM t1 ORDER BY a LIMIT 1;
+SHOW STATUS LIKE 'HANDLER_READ%';
+
+FLUSH STATUS;
+SELECT a FROM t1 ORDER BY a DESC LIMIT 1;
+SHOW STATUS LIKE 'HANDLER_READ%';
+
+FLUSH STATUS;
+SELECT a FROM t1 ORDER BY a LIMIT 3;
+SHOW STATUS LIKE 'HANDLER_READ%';
+
+FLUSH STATUS;
+SELECT a FROM t1 ORDER BY a DESC LIMIT 3;
+SHOW STATUS LIKE 'HANDLER_READ%';
+
+DROP TABLE t1;
+

sql/mysqld.cc

@@ -6439,6 +6439,7 @@ SHOW_VAR status_vars[]= {
   {"Handler_prepare",          (char*) offsetof(STATUS_VAR, ha_prepare_count),  SHOW_LONG_STATUS},
   {"Handler_read_first",       (char*) offsetof(STATUS_VAR, ha_read_first_count), SHOW_LONG_STATUS},
   {"Handler_read_key",         (char*) offsetof(STATUS_VAR, ha_read_key_count), SHOW_LONG_STATUS},
+  {"Handler_read_last",        (char*) offsetof(STATUS_VAR, ha_read_last_count), SHOW_LONG_STATUS},
   {"Handler_read_next",        (char*) offsetof(STATUS_VAR, ha_read_next_count), SHOW_LONG_STATUS},
   {"Handler_read_prev",        (char*) offsetof(STATUS_VAR, ha_read_prev_count), SHOW_LONG_STATUS},
   {"Handler_read_rnd",         (char*) offsetof(STATUS_VAR, ha_read_rnd_count), SHOW_LONG_STATUS},