SHOW STATUS does not anymore change local status variables (except com_show_status). Global status variables are still updated.

SHOW STATUS are not anymore put in slow query log because of no index usage.

Implemntation done by removing orig_sql_command and moving logic of SHOW STATUS to mysql_excute_command()
This simplifies code and allows us to remove some if statements all over the code.

Upgraded uc_update_queries[] to sql_command_flags and added more bitmaps to better categorize commands.
This allowed some overall simplifaction when testing sql_command.

Fixes bugs:
Bug#10210: running SHOW STATUS increments counters it shouldn't
Bug#19764: SHOW commands end up in the slow log as table scans


mysql-test/r/grant_cache.result:
  Fixed results after SHOW STATUS doesn't anymore affect status variables
mysql-test/r/information_schema.result:
  Added extra test to cover more code
mysql-test/r/query_cache.result:
  Remove resuts from previous tests
mysql-test/r/status.result:
  Added more tests for testing of last_query_cost and how SHOW STATUS affects status variables.
  (Bug#10210)
mysql-test/r/temp_table.result:
  Fixed results after SHOW STATUS doesn't anymore affect status variables
mysql-test/r/union.result:
  Fixed results after SHOW STATUS is not logged to slow query log
  (Bug#19764)
mysql-test/t/events_microsec.test:
  Disable warnings at init
mysql-test/t/information_schema.test:
  Added extra test to cover more code
mysql-test/t/query_cache.test:
  Remove resuts from previous tests
mysql-test/t/status.test:
  Added more tests for testing of last_query_cost and how SHOW STATUS affects status variables.
  (Bug #10210)
sql/mysql_priv.h:
  Added 'sql_command_flags'
sql/sql_class.cc:
  New function add_diff_to_status(), used to update global status variables when using SHOW STATUS
sql/sql_class.h:
  New function 'fill_information_schema_tables()'
  (One could not anymore use fill_derived_tables() for this as only_view_structures() is not relevant for information schema tables)
  Added defines for bit flags in sql_command_flags[]
sql/sql_lex.cc:
  Remove orig_sql_command
sql/sql_lex.h:
  Remove orig_sql_command
sql/sql_parse.cc:
  Rename uc_update_queries -> sql_command_flags.
  Enhanced 'sql_command_flags' to better classify SQL commands
  uc_update_queries[] != 0 is changed to (sql_command_flags[] & CF_CHANGES_DATA)
  lex->orig_sql_command == SQLCOM_END is changed to (sql_command_flags[lex->sql_command] & CF_STATUS_COMMAND) == 0)
  
  Simplify incrementing of thd->status_var.com_stat[] as we don't have to do special handling for SHOW commands.
  
  Split SQLCOM_SELECT handling in mysql_execute_command() to a separate function.
  Added special handling of SHOW STATUS commands in mysql_execute_command() and call common SQLCOM_SELECT handling.
  These changes allows us to easily fix that we save and restore status variables during execution of a SHOW STATUS command.
  Don't log SHOW STATUS commands to slow query log.
  
  This fixes Bug#10210 and Bug#19764 without adding additional 'if' code.
  (The new code is faster than the original as we now have fewer if's than before)
sql/sql_prepare.cc:
  Clean up prepare-check handling of SQLCOM commands by using sql_command_flags[]
  This simplifes code and ensures that code works even if someone forgets to put a new status commands into the switch statement.
sql/sql_select.cc:
  Remove special handling of SHOW STATUS.
  (This is now done in SQLCOM_SHOW_STATUS part in mysql_execute_command())
sql/sql_show.cc:
  Remove orig_sql_command
  Only change sql_command during 'open_normal_and_derived_tables()' (for views) and not for the full duration of generating data.
  Changed 'show status' to use thd->initial_status_var to ensure that the current statement is not affecting the to-be-used values.
  Use thd->fill_information_schema_tables() instead of 'thd->fill_derived_tables()' as the later wrongly checks the value of sql_command.
sql/sql_yacc.yy:
  Remove usage of orig_sql_command.
  One side effect of this is that we need to test for cursors if the current command is a SELECT or a SHOW command.
sql/structs.h:
  Updated comment

10 files changed, 108 insertions, 13 deletions

diff --git a/mysql-test/r/grant_cache.result b/mysql-test/r/grant_cache.result
index 925a5918c1b..2c6840d77d0 100644
--- a/mysql-test/r/grant_cache.result
+++ b/mysql-test/r/grant_cache.result
@@ -60,7 +60,7 @@ Variable_name	Value
 Qcache_hits	0
 show status like "Qcache_not_cached";
 Variable_name	Value
-Qcache_not_cached	5
+Qcache_not_cached	0
 select "user1";
 user1
 user1
@@ -72,7 +72,7 @@ Variable_name	Value
 Qcache_hits	0
 show status like "Qcache_not_cached";
 Variable_name	Value
-Qcache_not_cached	9
+Qcache_not_cached	1
 select * from t1;
 a	b	c
 1	1	1
@@ -85,7 +85,7 @@ Variable_name	Value
 Qcache_hits	1
 show status like "Qcache_not_cached";
 Variable_name	Value
-Qcache_not_cached	12
+Qcache_not_cached	1
 select a from t1 ;
 a
 1
@@ -98,7 +98,7 @@ Variable_name	Value
 Qcache_hits	2
 show status like "Qcache_not_cached";
 Variable_name	Value
-Qcache_not_cached	15
+Qcache_not_cached	1
 select c from t1;
 c
 1
@@ -111,7 +111,7 @@ Variable_name	Value
 Qcache_hits	3
 show status like "Qcache_not_cached";
 Variable_name	Value
-Qcache_not_cached	18
+Qcache_not_cached	1
 show grants for current_user();
 Grants for @localhost
 GRANT USAGE ON *.* TO ''@'localhost'
@@ -144,7 +144,7 @@ Variable_name	Value
 Qcache_hits	7
 show status like "Qcache_not_cached";
 Variable_name	Value
-Qcache_not_cached	22
+Qcache_not_cached	2
 select "user3";
 user3
 user3
@@ -168,7 +168,7 @@ Variable_name	Value
 Qcache_hits	7
 show status like "Qcache_not_cached";
 Variable_name	Value
-Qcache_not_cached	30
+Qcache_not_cached	7
 select "user4";
 user4
 user4
@@ -198,7 +198,7 @@ Variable_name	Value
 Qcache_hits	8
 show status like "Qcache_not_cached";
 Variable_name	Value
-Qcache_not_cached	34
+Qcache_not_cached	8
 set names binary;
 delete from mysql.user where user in ("mysqltest_1","mysqltest_2","mysqltest_3");
 delete from mysql.db where user in ("mysqltest_1","mysqltest_2","mysqltest_3");
diff --git a/mysql-test/r/information_schema.result b/mysql-test/r/information_schema.result
index 070049b303a..94e0a5ffd2a 100644
--- a/mysql-test/r/information_schema.result
+++ b/mysql-test/r/information_schema.result
@@ -199,6 +199,8 @@ select table_name, column_name, privileges from information_schema.columns
 where table_schema = 'mysqltest' and table_name = 'v1';
 table_name	column_name	privileges
 v1	c	select
+explain select * from v1;
+ERROR HY000: EXPLAIN/SHOW can not be issued; lacking privileges for underlying table
 drop view v1, mysqltest.v1;
 drop tables mysqltest.t4, mysqltest.t1, t2, t3, t5;
 drop database mysqltest;
diff --git a/mysql-test/r/query_cache.result b/mysql-test/r/query_cache.result
index 40aa88439b9..5f72b229ab5 100644
--- a/mysql-test/r/query_cache.result
+++ b/mysql-test/r/query_cache.result
@@ -1050,6 +1050,7 @@ Qcache_hits	1
 drop table t1;
 create table t1 (a int);
 insert into t1 values (1),(2);
+drop procedure if exists p1;
 CREATE PROCEDURE `p1`()
 begin
 Declare c1 cursor for select a from t1;
diff --git a/mysql-test/r/status.result b/mysql-test/r/status.result
index e83ade78cf6..83c6a6f5288 100644
--- a/mysql-test/r/status.result
+++ b/mysql-test/r/status.result
@@ -23,6 +23,32 @@ select 1;
 show status like 'last_query_cost';
 Variable_name	Value
 Last_query_cost	0.000000
+create table t1 (a int);
+insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
+insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
+insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
+insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
+insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
+select * from t1 where a=6;
+a
+6
+6
+6
+6
+6
+show status like 'last_query_cost';
+Variable_name	Value
+Last_query_cost	12.084449
+show status like 'last_query_cost';
+Variable_name	Value
+Last_query_cost	12.084449
+select 1;
+1
+1
+show status like 'last_query_cost';
+Variable_name	Value
+Last_query_cost	0.000000
+drop table t1;
 FLUSH STATUS;
 SHOW STATUS LIKE 'max_used_connections';
 Variable_name	Value
@@ -43,3 +69,27 @@ SHOW STATUS LIKE 'max_used_connections';
 Variable_name	Value
 Max_used_connections	5
 SET GLOBAL thread_cache_size=@save_thread_cache_size;
+show status like 'com_show_status';
+Variable_name	Value
+Com_show_status	3
+show status like 'hand%write%';
+Variable_name	Value
+Handler_write	0
+show status like '%tmp%';
+Variable_name	Value
+Created_tmp_disk_tables	0
+Created_tmp_files	0
+Created_tmp_tables	0
+show status like 'hand%write%';
+Variable_name	Value
+Handler_write	0
+show status like '%tmp%';
+Variable_name	Value
+Created_tmp_disk_tables	0
+Created_tmp_files	0
+Created_tmp_tables	0
+show status like 'com_show_status';
+Variable_name	Value
+Com_show_status	8
+rnd_diff	tmp_table_diff
+20	8
diff --git a/mysql-test/r/temp_table.result b/mysql-test/r/temp_table.result
index 2b3e9087cf7..637f74a1d50 100644
--- a/mysql-test/r/temp_table.result
+++ b/mysql-test/r/temp_table.result
@@ -98,7 +98,7 @@ d
 show status like "created_tmp%tables";
 Variable_name	Value
 Created_tmp_disk_tables	0
-Created_tmp_tables	2
+Created_tmp_tables	1
 drop table t1;
 create temporary table v1 as select 'This is temp. table' A;
 create view v1 as select 'This is view' A;
diff --git a/mysql-test/r/union.result b/mysql-test/r/union.result
index 4280ae28e3c..43598caa86f 100644
--- a/mysql-test/r/union.result
+++ b/mysql-test/r/union.result
@@ -836,27 +836,27 @@ count(*)
 26
 show status like 'Slow_queries';
 Variable_name	Value
-Slow_queries	1
+Slow_queries	0
 select count(*) from t1 where b=13;
 count(*)
 10
 show status like 'Slow_queries';
 Variable_name	Value
-Slow_queries	3
+Slow_queries	1
 select count(*) from t1 where b=13 union select count(*) from t1 where a=7;
 count(*)
 10
 26
 show status like 'Slow_queries';
 Variable_name	Value
-Slow_queries	5
+Slow_queries	2
 select count(*) from t1 where a=7 union select count(*) from t1 where b=13;
 count(*)
 26
 10
 show status like 'Slow_queries';
 Variable_name	Value
-Slow_queries	7
+Slow_queries	3
 flush status;
 select a from t1 where b not in (1,2,3) union select a from t1 where b not in (4,5,6);
 a
diff --git a/mysql-test/t/events_microsec.test b/mysql-test/t/events_microsec.test
index e01120a0756..e4d57bf4ae1 100644
--- a/mysql-test/t/events_microsec.test
+++ b/mysql-test/t/events_microsec.test
@@ -1,4 +1,7 @@
+--disable_warnings
 create database if not exists events_test;
+--enable_warnings
+
 use events_test;
 
 --error ER_NOT_SUPPORTED_YET
diff --git a/mysql-test/t/information_schema.test b/mysql-test/t/information_schema.test
index 19e3ef97f1e..73aea01dfa2 100644
--- a/mysql-test/t/information_schema.test
+++ b/mysql-test/t/information_schema.test
@@ -80,6 +80,8 @@ connect (user4,localhost,mysqltest_3,,mysqltest);
 connection user4;
 select table_name, column_name, privileges from information_schema.columns
 where table_schema = 'mysqltest' and table_name = 'v1';
+--error 1345
+explain select * from v1;
 connection default;
 
 drop view v1, mysqltest.v1;
diff --git a/mysql-test/t/query_cache.test b/mysql-test/t/query_cache.test
index e2ff20e6ecc..2c94fe63c04 100644
--- a/mysql-test/t/query_cache.test
+++ b/mysql-test/t/query_cache.test
@@ -765,6 +765,9 @@ drop table t1;
 create table t1 (a int);
 insert into t1 values (1),(2);
 
+--disable_warnings
+drop procedure if exists p1;
+--enable_warnings
 delimiter //;
 CREATE PROCEDURE `p1`()
 begin
diff --git a/mysql-test/t/status.test b/mysql-test/t/status.test
index 1a71425d2a7..55f9d95adc5 100644
--- a/mysql-test/t/status.test
+++ b/mysql-test/t/status.test
@@ -48,6 +48,19 @@ connection default;
 
 select 1;
 show status like 'last_query_cost';
+create table t1 (a int);
+insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
+insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
+insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
+insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
+insert into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
+select * from t1 where a=6;
+show status like 'last_query_cost';
+# Ensure value dosn't change by second status call
+show status like 'last_query_cost';
+select 1;
+show status like 'last_query_cost';
+drop table t1;
 
 #
 # Test for Bug #15933 max_used_connections is wrong after FLUSH STATUS
@@ -144,3 +157,24 @@ disconnect con2;
 disconnect con1;
 
 # End of 5.0 tests
+
+#
+# Ensure that SHOW STATUS only changes global status variables
+#
+
+connect (con1,localhost,root,,);
+let $rnd_next = `show global status like 'handler_read_rnd_next'`;
+let $tmp_table = `show global status like 'Created_tmp_tables'`;
+show status like 'com_show_status';
+show status like 'hand%write%';
+show status like '%tmp%';
+show status like 'hand%write%';
+show status like '%tmp%';
+show status like 'com_show_status';
+let $rnd_next2 = `show global status like 'handler_read_rnd_next'`;
+let $tmp_table2 = `show global status like 'Created_tmp_tables'`;
+--disable_query_log
+eval select substring_index('$rnd_next2',0x9,-1)-substring_index('$rnd_next',0x9,-1) as rnd_diff, substring_index('$tmp_table2',0x9,-1)-substring_index('$tmp_table',0x9,-1) as tmp_table_diff;
+--enable_query_log
+
+# End of 5.1 tests