PS-5783: New thread variables: innodb_(force_index_)records_in_range

These variables make it possible to override reconds_in_range, effectively
skipping its computation. This could be useful in some cases where reconds_in_range
takes up most of the query cost.

mysql-test/suite/sys_vars/r/innodb_force_index_records_in_range_basic.result

@@ -0,0 +1,67 @@
+SELECT @@GLOBAL.innodb_force_index_records_in_range;
+@@GLOBAL.innodb_force_index_records_in_range
+0
+0 Expected
+SET @@GLOBAL.innodb_force_index_records_in_range=100;
+1 Expected
+SELECT @@GLOBAL.innodb_force_index_records_in_range;
+@@GLOBAL.innodb_force_index_records_in_range
+100
+100 Expected
+SET @@GLOBAL.innodb_force_index_records_in_range=DEFAULT;
+1 Expected
+SELECT @@GLOBAL.innodb_force_index_records_in_range;
+@@GLOBAL.innodb_force_index_records_in_range
+0
+0 Expected
+SELECT @@GLOBAL.innodb_force_index_records_in_range = VARIABLE_VALUE
+FROM performance_schema.global_variables
+WHERE VARIABLE_NAME='innodb_force_index_records_in_range';
+@@GLOBAL.innodb_force_index_records_in_range = VARIABLE_VALUE
+1
+1 Expected
+SELECT @@GLOBAL.innodb_force_index_records_in_range;
+@@GLOBAL.innodb_force_index_records_in_range
+0
+0 Expected
+SELECT VARIABLE_VALUE
+FROM performance_schema.global_variables 
+WHERE VARIABLE_NAME='innodb_force_index_records_in_range';
+VARIABLE_VALUE
+0
+0 Expected
+SELECT @@innodb_force_index_records_in_range = VARIABLE_VALUE
+FROM performance_schema.session_variables
+WHERE VARIABLE_NAME='innodb_force_index_records_in_range';
+@@innodb_force_index_records_in_range = VARIABLE_VALUE
+1
+1 Expected
+SELECT VARIABLE_VALUE
+FROM performance_schema.session_variables 
+WHERE VARIABLE_NAME='innodb_force_index_records_in_range';
+VARIABLE_VALUE
+0
+0 Expected
+SELECT @@innodb_force_index_records_in_range = @@GLOBAL.innodb_force_index_records_in_range;
+@@innodb_force_index_records_in_range = @@GLOBAL.innodb_force_index_records_in_range
+1
+1 Expected
+SELECT @@innodb_force_index_records_in_range;
+@@innodb_force_index_records_in_range
+0
+0 Expected
+SELECT @@local.innodb_force_index_records_in_range;
+@@local.innodb_force_index_records_in_range
+0
+0 Expected
+SELECT @@SESSION.innodb_force_index_records_in_range;
+@@SESSION.innodb_force_index_records_in_range
+0
+0 Expected
+SELECT @@GLOBAL.innodb_force_index_records_in_range;
+@@GLOBAL.innodb_force_index_records_in_range
+0
+0 Expected
+SELECT innodb_force_index_records_in_range;
+ERROR 42S22: Unknown column 'innodb_force_index_records_in_range' in 'field list'
+Expected error 'Unknow column in field list'

mysql-test/suite/sys_vars/r/innodb_records_in_range_basic.result

@@ -0,0 +1,67 @@
+SELECT @@GLOBAL.innodb_records_in_range;
+@@GLOBAL.innodb_records_in_range
+0
+0 Expected
+SET @@GLOBAL.innodb_records_in_range=100;
+1 Expected
+SELECT @@GLOBAL.innodb_records_in_range;
+@@GLOBAL.innodb_records_in_range
+100
+100 Expected
+SET @@GLOBAL.innodb_records_in_range=DEFAULT;
+1 Expected
+SELECT @@GLOBAL.innodb_records_in_range;
+@@GLOBAL.innodb_records_in_range
+0
+0 Expected
+SELECT @@GLOBAL.innodb_records_in_range = VARIABLE_VALUE
+FROM performance_schema.global_variables
+WHERE VARIABLE_NAME='innodb_records_in_range';
+@@GLOBAL.innodb_records_in_range = VARIABLE_VALUE
+1
+1 Expected
+SELECT @@GLOBAL.innodb_records_in_range;
+@@GLOBAL.innodb_records_in_range
+0
+0 Expected
+SELECT VARIABLE_VALUE
+FROM performance_schema.global_variables 
+WHERE VARIABLE_NAME='innodb_records_in_range';
+VARIABLE_VALUE
+0
+0 Expected
+SELECT @@innodb_records_in_range = VARIABLE_VALUE
+FROM performance_schema.session_variables
+WHERE VARIABLE_NAME='innodb_records_in_range';
+@@innodb_records_in_range = VARIABLE_VALUE
+1
+1 Expected
+SELECT VARIABLE_VALUE
+FROM performance_schema.session_variables 
+WHERE VARIABLE_NAME='innodb_records_in_range';
+VARIABLE_VALUE
+0
+0 Expected
+SELECT @@innodb_records_in_range = @@GLOBAL.innodb_records_in_range;
+@@innodb_records_in_range = @@GLOBAL.innodb_records_in_range
+1
+1 Expected
+SELECT @@innodb_records_in_range;
+@@innodb_records_in_range
+0
+0 Expected
+SELECT @@local.innodb_records_in_range;
+@@local.innodb_records_in_range
+0
+0 Expected
+SELECT @@SESSION.innodb_records_in_range;
+@@SESSION.innodb_records_in_range
+0
+0 Expected
+SELECT @@GLOBAL.innodb_records_in_range;
+@@GLOBAL.innodb_records_in_range
+0
+0 Expected
+SELECT innodb_records_in_range;
+ERROR 42S22: Unknown column 'innodb_records_in_range' in 'field list'
+Expected error 'Unknow column in field list'

mysql-test/suite/sys_vars/t/innodb_force_index_records_in_range_basic.test

@@ -0,0 +1,61 @@
+# Display default value
+SELECT @@GLOBAL.innodb_force_index_records_in_range;
+--echo 0 Expected
+
+# Check if value can be set
+SET @@GLOBAL.innodb_force_index_records_in_range=100;
+--echo 1 Expected
+
+SELECT @@GLOBAL.innodb_force_index_records_in_range;
+--echo 100 Expected
+
+SET @@GLOBAL.innodb_force_index_records_in_range=DEFAULT;
+--echo 1 Expected
+
+SELECT @@GLOBAL.innodb_force_index_records_in_range;
+--echo 0 Expected
+
+# Check if the value in GLOBAL TABLE matches value in variable
+SELECT @@GLOBAL.innodb_force_index_records_in_range = VARIABLE_VALUE
+FROM performance_schema.global_variables
+WHERE VARIABLE_NAME='innodb_force_index_records_in_range';
+--echo 1 Expected
+
+SELECT @@GLOBAL.innodb_force_index_records_in_range;
+--echo 0 Expected
+
+SELECT VARIABLE_VALUE
+FROM performance_schema.global_variables 
+WHERE VARIABLE_NAME='innodb_force_index_records_in_range';
+--echo 0 Expected
+
+SELECT @@innodb_force_index_records_in_range = VARIABLE_VALUE
+FROM performance_schema.session_variables
+WHERE VARIABLE_NAME='innodb_force_index_records_in_range';
+--echo 1 Expected
+
+SELECT VARIABLE_VALUE
+FROM performance_schema.session_variables 
+WHERE VARIABLE_NAME='innodb_force_index_records_in_range';
+--echo 0 Expected
+
+# Check if accessing variable with and without GLOBAL point to same variable
+SELECT @@innodb_force_index_records_in_range = @@GLOBAL.innodb_force_index_records_in_range;
+--echo 1 Expected
+
+# Check if innodb_force_index_records_in_range can be accessed with and without @@ sign
+SELECT @@innodb_force_index_records_in_range;
+--echo 0 Expected
+
+SELECT @@local.innodb_force_index_records_in_range;
+--echo 0 Expected
+
+SELECT @@SESSION.innodb_force_index_records_in_range;
+--echo 0 Expected
+
+SELECT @@GLOBAL.innodb_force_index_records_in_range;
+--echo 0 Expected
+
+--Error ER_BAD_FIELD_ERROR
+SELECT innodb_force_index_records_in_range;
+--echo Expected error 'Unknow column in field list'

mysql-test/suite/sys_vars/t/innodb_records_in_range_basic.test

@@ -0,0 +1,61 @@
+# Display default value
+SELECT @@GLOBAL.innodb_records_in_range;
+--echo 0 Expected
+
+# Check if value can be set
+SET @@GLOBAL.innodb_records_in_range=100;
+--echo 1 Expected
+
+SELECT @@GLOBAL.innodb_records_in_range;
+--echo 100 Expected
+
+SET @@GLOBAL.innodb_records_in_range=DEFAULT;
+--echo 1 Expected
+
+SELECT @@GLOBAL.innodb_records_in_range;
+--echo 0 Expected
+
+# Check if the value in GLOBAL TABLE matches value in variable
+SELECT @@GLOBAL.innodb_records_in_range = VARIABLE_VALUE
+FROM performance_schema.global_variables
+WHERE VARIABLE_NAME='innodb_records_in_range';
+--echo 1 Expected
+
+SELECT @@GLOBAL.innodb_records_in_range;
+--echo 0 Expected
+
+SELECT VARIABLE_VALUE
+FROM performance_schema.global_variables 
+WHERE VARIABLE_NAME='innodb_records_in_range';
+--echo 0 Expected
+
+SELECT @@innodb_records_in_range = VARIABLE_VALUE
+FROM performance_schema.session_variables
+WHERE VARIABLE_NAME='innodb_records_in_range';
+--echo 1 Expected
+
+SELECT VARIABLE_VALUE
+FROM performance_schema.session_variables 
+WHERE VARIABLE_NAME='innodb_records_in_range';
+--echo 0 Expected
+
+# Check if accessing variable with and without GLOBAL point to same variable
+SELECT @@innodb_records_in_range = @@GLOBAL.innodb_records_in_range;
+--echo 1 Expected
+
+# Check if innodb_records_in_range can be accessed with and without @@ sign
+SELECT @@innodb_records_in_range;
+--echo 0 Expected
+
+SELECT @@local.innodb_records_in_range;
+--echo 0 Expected
+
+SELECT @@SESSION.innodb_records_in_range;
+--echo 0 Expected
+
+SELECT @@GLOBAL.innodb_records_in_range;
+--echo 0 Expected
+
+--Error ER_BAD_FIELD_ERROR
+SELECT innodb_records_in_range;
+--echo Expected error 'Unknow column in field list'

storage/innobase/handler/ha_innodb.cc

@@ -916,6 +916,24 @@ static PSI_file_info all_innodb_files[] = {
 #endif /* UNIV_PFS_IO */
 #endif /* HAVE_PSI_INTERFACE */
 
+static MYSQL_THDVAR_UINT(records_in_range, PLUGIN_VAR_RQCMDARG,
+                         "Used to override the result of records_in_range(). "
+                         "Set to a positive number to override",
+                         NULL, NULL, 0,
+                         /* min */ 0, /* max */ INT_MAX, 0);
+
+static MYSQL_THDVAR_UINT(force_index_records_in_range, PLUGIN_VAR_RQCMDARG,
+                         "Used to override the result of records_in_range() "
+                         "when FORCE INDEX is used.",
+                         NULL, NULL, 0,
+                         /* min */ 0, /* max */ INT_MAX, 0);
+
+uint innodb_force_index_records_in_range(THD *thd) {
+  return THDVAR(thd, force_index_records_in_range);
+}
+
+uint innodb_records_in_range(THD *thd) { return THDVAR(thd, records_in_range); }
+
 /** Plugin update function to handle validation and then switch the
 innodb_doublewrite mode
 @param[in]  thd thread handle
@@ -24354,6 +24372,8 @@ static SYS_VAR *innobase_system_variables[] = {
     MYSQL_SYSVAR(compressed_columns_zip_level),
     MYSQL_SYSVAR(compressed_columns_threshold),
     MYSQL_SYSVAR(ft_ignore_stopwords),
+    MYSQL_SYSVAR(records_in_range),
+    MYSQL_SYSVAR(force_index_records_in_range),
     nullptr};
 
 mysql_declare_plugin(innobase){

storage/innobase/handler/ha_innodb.h

@@ -1438,6 +1438,9 @@ bool innobase_build_index_translation(const TABLE *table,
                                       dict_table_t *ib_table,
                                       INNOBASE_SHARE *share);
 
+uint innodb_force_index_records_in_range(THD *thd);
+uint innodb_records_in_range(THD *thd);
+
 /** Free InnoDB session specific data.
 @param[in,out]	thd	MySQL thread handler. */
 void thd_free_innodb_session(THD *thd) noexcept;

storage/innobase/handler/ha_innopart.cc

@@ -3340,6 +3340,17 @@ ha_rows ha_innopart::records_in_range(uint keynr, key_range *min_key,
 
   ut_ad(m_prebuilt->trx == thd_to_trx(ha_thd()));
 
+  ha_rows ret = innodb_records_in_range(ha_thd());
+  if (ret) {
+    return ret;
+  }
+  if (table->force_index) {
+    const ha_rows force_rows = innodb_force_index_records_in_range(ha_thd());
+    if (force_rows) {
+      return force_rows;
+    }
+  }
+
   m_prebuilt->trx->op_info = (char *)"estimating records in index range";
 
   active_index = keynr;