MDEV-8633: information_schema.index_statistics doesn't delete

item when drop table indexes or drop table;

Problem was that table and index statistics is removed from
persistent tables but not from memory cache. Added functions
to remove table and index statistics from memory cache.

mysql-test/r/information_schema_stats.result

+set global userstat=1;
+create table just_a_test(id int,first_name varchar(10),last_name varchar(10),address varchar(100),phone bigint,email varchar(30), state varchar(30));
+insert into just_a_test values(1,'fa','la','china_a',11111111,'fa_la@163.com','California'),
+(2,'fb','lb','china_b',22222222,'fb_lb@163.com','Arizona'),
+(3,'fc','lc','china_c',33333333,'fc_lc@163.com','California'),
+(4,'fd','ld','china_d',44444444,'fd_ld@163.com','Utah'),
+(5,'fe','le','china_e',55555555,'fe_le@163.com','Arizona');
+alter table just_a_test add primary key (id);
+alter table just_a_test add key IND_just_a_test_first_name_last_name(first_name,last_name);
+alter table just_a_test add key IND_just_a_test_state(state);
+select count(*) from just_a_test where first_name='fc' and last_name='lc';
+count(*)
+1
+select count(*) from just_a_test where state = 'California';
+count(*)
+2
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	INDEX_NAME	ROWS_READ
+test	just_a_test	IND_just_a_test_state	2
+test	just_a_test	IND_just_a_test_first_name_last_name	1
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	ROWS_READ	ROWS_CHANGED	ROWS_CHANGED_X_INDEXES
+test	just_a_test	18	5	5
+alter table just_a_test drop key IND_just_a_test_first_name_last_name;
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	INDEX_NAME	ROWS_READ
+test	just_a_test	IND_just_a_test_state	2
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	ROWS_READ	ROWS_CHANGED	ROWS_CHANGED_X_INDEXES
+test	just_a_test	23	5	5
+alter table just_a_test drop column state;
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	INDEX_NAME	ROWS_READ
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	ROWS_READ	ROWS_CHANGED	ROWS_CHANGED_X_INDEXES
+test	just_a_test	28	5	5
+drop table just_a_test;
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	INDEX_NAME	ROWS_READ
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	ROWS_READ	ROWS_CHANGED	ROWS_CHANGED_X_INDEXES
+create table just_a_test(id int not null primary key,first_name varchar(10),last_name varchar(10),address varchar(100),phone bigint,email varchar(30), state varchar(30),key(first_name,last_name),key(state));
+insert into just_a_test values(1,'fa','la','china_a',11111111,'fa_la@163.com','California'),
+(2,'fb','lb','china_b',22222222,'fb_lb@163.com','Arizona'),
+(3,'fc','lc','china_c',33333333,'fc_lc@163.com','California'),
+(4,'fd','ld','china_d',44444444,'fd_ld@163.com','Utah'),
+(5,'fe','le','china_e',55555555,'fe_le@163.com','Arizona');
+select count(*) from just_a_test where first_name='fc' and last_name='lc';
+count(*)
+1
+select count(*) from just_a_test where state = 'California';
+count(*)
+2
+select count(*) from just_a_test where id between 2 and 4;
+count(*)
+3
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	INDEX_NAME	ROWS_READ
+test	just_a_test	first_name	1
+test	just_a_test	state	2
+test	just_a_test	PRIMARY	5
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	ROWS_READ	ROWS_CHANGED	ROWS_CHANGED_X_INDEXES
+test	just_a_test	8	5	15
+drop table just_a_test;
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	INDEX_NAME	ROWS_READ
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+TABLE_SCHEMA	TABLE_NAME	ROWS_READ	ROWS_CHANGED	ROWS_CHANGED_X_INDEXES
+set global userstat=0;

mysql-test/r/status_user.result

@@ -128,16 +128,12 @@ handler_read_key
 set @@global.userstat=0;
 select * from information_schema.index_statistics;
 TABLE_SCHEMA	TABLE_NAME	INDEX_NAME	ROWS_READ
-test	t1	PRIMARY	2
 select * from information_schema.table_statistics;
 TABLE_SCHEMA	TABLE_NAME	ROWS_READ	ROWS_CHANGED	ROWS_CHANGED_X_INDEXES
-test	t1	6	13	13
 show table_statistics;
 Table_schema	Table_name	Rows_read	Rows_changed	Rows_changed_x_#indexes
-test	t1	6	13	13
 show index_statistics;
 Table_schema	Table_name	Index_name	Rows_read
-test	t1	PRIMARY	2
 select TOTAL_CONNECTIONS, CONCURRENT_CONNECTIONS, ROWS_READ, ROWS_SENT, ROWS_DELETED, ROWS_INSERTED, ROWS_UPDATED, SELECT_COMMANDS, UPDATE_COMMANDS, OTHER_COMMANDS, COMMIT_TRANSACTIONS, ROLLBACK_TRANSACTIONS, DENIED_CONNECTIONS, LOST_CONNECTIONS, ACCESS_DENIED, EMPTY_QUERIES from information_schema.client_statistics;;
 TOTAL_CONNECTIONS	1
 CONCURRENT_CONNECTIONS	0

mysql-test/t/information_schema_stats.test

+#
+# MDEV-8633: information_schema.index_statistics doesn't delete item when drop table indexes or drop table;
+#
+set global userstat=1;
+create table just_a_test(id int,first_name varchar(10),last_name varchar(10),address varchar(100),phone bigint,email varchar(30), state varchar(30));
+insert into just_a_test values(1,'fa','la','china_a',11111111,'fa_la@163.com','California'),
+(2,'fb','lb','china_b',22222222,'fb_lb@163.com','Arizona'),
+(3,'fc','lc','china_c',33333333,'fc_lc@163.com','California'),
+(4,'fd','ld','china_d',44444444,'fd_ld@163.com','Utah'),
+(5,'fe','le','china_e',55555555,'fe_le@163.com','Arizona');
+alter table just_a_test add primary key (id);
+alter table just_a_test add key IND_just_a_test_first_name_last_name(first_name,last_name);
+alter table just_a_test add key IND_just_a_test_state(state);
+select count(*) from just_a_test where first_name='fc' and last_name='lc';
+select count(*) from just_a_test where state = 'California';
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+alter table just_a_test drop key IND_just_a_test_first_name_last_name;
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+alter table just_a_test drop column state;
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+drop table just_a_test;
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+#
+# Test direct drop table
+#
+create table just_a_test(id int not null primary key,first_name varchar(10),last_name varchar(10),address varchar(100),phone bigint,email varchar(30), state varchar(30),key(first_name,last_name),key(state));
+insert into just_a_test values(1,'fa','la','china_a',11111111,'fa_la@163.com','California'),
+(2,'fb','lb','china_b',22222222,'fb_lb@163.com','Arizona'),
+(3,'fc','lc','china_c',33333333,'fc_lc@163.com','California'),
+(4,'fd','ld','china_d',44444444,'fd_ld@163.com','Utah'),
+(5,'fe','le','china_e',55555555,'fe_le@163.com','Arizona');
+select count(*) from just_a_test where first_name='fc' and last_name='lc';
+select count(*) from just_a_test where state = 'California';
+select count(*) from just_a_test where id between 2 and 4;
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+drop table just_a_test;
+select * from information_schema.index_statistics where table_schema='test' and table_name='just_a_test';
+select * from information_schema.table_statistics where table_schema='test' and table_name='just_a_test';
+set global userstat=0;

sql/sql_show.cc

@@ -3460,6 +3460,100 @@ int fill_schema_table_stats(THD *thd, TABLE_LIST *tables, COND *cond)
   DBUG_RETURN(0);
 }
 
+/* Remove all indexes for a given table from global index statistics */
+
+static
+int del_global_index_stats_for_table(THD *thd, uchar* cache_key, uint cache_key_length)
+{
+  int res = 0;
+  DBUG_ENTER("del_global_index_stats_for_table");
+
+  mysql_mutex_lock(&LOCK_global_index_stats);
+
+  for (uint i= 0; i < global_index_stats.records;)
+  {
+    INDEX_STATS *index_stats =
+      (INDEX_STATS*) my_hash_element(&global_index_stats, i);
+
+    /* We search correct db\0table_name\0 string */
+    if (index_stats &&
+	index_stats->index_name_length >= cache_key_length &&
+	!memcmp(index_stats->index, cache_key, cache_key_length))
+    {
+      res= my_hash_delete(&global_index_stats, (uchar*)index_stats);
+      /*
+          In our HASH implementation on deletion one elements
+          is moved into a place where a deleted element was,
+          and the last element is moved into the empty space.
+          Thus we need to re-examine the current element, but
+          we don't have to restart the search from the beginning.
+      */
+    }
+    else
+      i++;
+  }
+
+  mysql_mutex_unlock(&LOCK_global_index_stats);
+  DBUG_RETURN(res);
+}
+
+/* Remove a table from global table statistics */
+
+int del_global_table_stat(THD *thd, LEX_STRING *db, LEX_STRING *table)
+{
+  TABLE_STATS *table_stats;
+  int res = 0;
+  uchar *cache_key;
+  uint cache_key_length;
+  DBUG_ENTER("del_global_table_stat");
+
+  cache_key_length= db->length + 1 + table->length + 1;
+
+  if(!(cache_key= (uchar *)my_malloc(cache_key_length,
+                                     MYF(MY_WME | MY_ZEROFILL))))
+  {
+    /* Out of memory error already given */
+    res = 1;
+    goto end;
+  }
+
+  memcpy(cache_key, db->str, db->length);
+  memcpy(cache_key + db->length + 1, table->str, table->length);
+
+  res= del_global_index_stats_for_table(thd, cache_key, cache_key_length);
+
+  mysql_mutex_lock(&LOCK_global_table_stats);
+
+  if((table_stats= (TABLE_STATS*) my_hash_search(&global_table_stats,
+                                                cache_key,
+                                                cache_key_length)))
+    res= my_hash_delete(&global_table_stats, (uchar*)table_stats);
+
+  my_free(cache_key);
+  mysql_mutex_unlock(&LOCK_global_table_stats);
+
+end:
+  DBUG_RETURN(res);
+}
+
+/* Remove a index from global index statistics */
+
+int del_global_index_stat(THD *thd, TABLE* table, KEY* key_info)
+{
+  INDEX_STATS *index_stats;
+  uint key_length= table->s->table_cache_key.length + key_info->name_length + 1;
+  int res = 0;
+  DBUG_ENTER("del_global_index_stat");
+  mysql_mutex_lock(&LOCK_global_index_stats);
+
+  if((index_stats= (INDEX_STATS*) my_hash_search(&global_index_stats,
+                                                key_info->cache_name,
+                                                key_length)))
+    res= my_hash_delete(&global_index_stats, (uchar*)index_stats);
+
+  mysql_mutex_unlock(&LOCK_global_index_stats);
+  DBUG_RETURN(res);
+}
 
 /* Fill information schema table with index statistics */
 

sql/sql_show.h

@@ -113,7 +113,8 @@ void view_store_options(THD *thd, TABLE_LIST *table, String *buff);
 void init_fill_schema_files_row(TABLE* table);
 bool schema_table_store_record(THD *thd, TABLE *table);
 void initialize_information_schema_acl();
-
+int del_global_index_stat(THD *thd, TABLE* tab, KEY* key_info);
+int del_global_table_stat(THD *thd, LEX_STRING *db, LEX_STRING *table);
 ST_SCHEMA_TABLE *find_schema_table(THD *thd, const char* table_name);
 ST_SCHEMA_TABLE *get_schema_table(enum enum_schema_tables schema_table_idx);
 int make_schema_select(THD *thd,  SELECT_LEX *sel,

sql/sql_statistics.cc

@@ -29,6 +29,7 @@
 #include "sql_statistics.h"
 #include "opt_range.h"
 #include "my_atomic.h"
+#include "sql_show.h"
 
 /*
   The system variable 'use_stat_tables' can take one of the
@@ -3193,6 +3194,10 @@ int delete_statistics_for_table(THD *thd, LEX_STRING *db, LEX_STRING *tab)
       rc= 1;
   }
 
+  err= del_global_table_stat(thd, db, tab);
+  if (err & !rc)
+      rc= 1;
+
   thd->restore_stmt_binlog_format(save_binlog_format);
 
   close_system_tables(thd, &open_tables_backup);
@@ -3339,6 +3344,10 @@ int delete_statistics_for_index(THD *thd, TABLE *tab, KEY *key_info,
     }
   }
 
+  err= del_global_index_stat(thd, tab, key_info);
+  if (err && !rc)
+    rc= 1;
+
   thd->restore_stmt_binlog_format(save_binlog_format);
 
   close_system_tables(thd, &open_tables_backup);