Added SHOW OPEN TABLES. Thanks to Antony T Curtis <antony@abacus.co.uk>

for the code.

Docs/manual.texi

@@ -19889,7 +19889,7 @@ commands to examine and kill threads.
 
 @example
    SHOW DATABASES [LIKE wild]
-or SHOW TABLES [FROM db_name] [LIKE wild]
+or SHOW [OPEN] TABLES [FROM db_name] [LIKE wild]
 or SHOW COLUMNS FROM tbl_name [FROM db_name] [LIKE wild]
 or SHOW INDEX FROM tbl_name [FROM db_name]
 or SHOW TABLE STATUS [FROM db_name] [LIKE wild]
@@ -19945,6 +19945,10 @@ get this list using the @code{mysqlshow db_name} command.
 will not show up in the output from @code{SHOW TABLES} or @code{mysqlshow
 db_name}.
 
+@code{SHOW OPEN TABLES} lists the tables that are currently open in
+the table cache. @xref{Table cache}.  The @code{Comment} field tells
+how many times the table is @code{cached} and @code{in_use}.
+
 @code{SHOW COLUMNS} lists the columns in a given table.  If the column
 types are different than you expect them to be based on a @code{CREATE
 TABLE} statement, note that @strong{MySQL} sometimes changes column

sql/gen_lex_hash.cc

@@ -472,7 +472,7 @@ int main(int argc,char **argv)
   int error;
 
   MY_INIT(argv[0]);
-  start_value=2610463L; best_t1=8358376L;  best_t2=860646L;  best_type=2; /* mode=4111  add=8  func_type: 0 */
+  start_value=5206280L; best_t1=590774L;  best_t2=5977654L;  best_type=1; /* mode=6229  add=2  func_type: 0 */
   if (get_options(argc,(char **) argv))
     exit(1);
 

sql/lex.h

@@ -223,6 +223,7 @@ static SYMBOL symbols[] = {
   { "NOT",		SYM(NOT),0,0},
   { "NULL",		SYM(NULL_SYM),0,0},
   { "ON",		SYM(ON),0,0},
+  { "OPEN",		SYM(OPEN_SYM),0,0},
   { "OPTIMIZE",		SYM(OPTIMIZE),0,0},
   { "OPTION",		SYM(OPTION),0,0},
   { "OPTIONALLY",	SYM(OPTIONALLY),0,0},

sql/mysql_priv.h

@@ -354,6 +354,7 @@ Field *find_field_in_table(THD *thd,TABLE *table,const char *name,uint length,
 
 /* sql_list.c */
 int mysqld_show_dbs(THD *thd,const char *wild);
+int mysqld_show_open_tables(THD *thd,const char *db,const char *wild);
 int mysqld_show_tables(THD *thd,const char *db,const char *wild);
 int mysqld_extend_show_tables(THD *thd,const char *db,const char *wild);
 int mysqld_show_fields(THD *thd,TABLE_LIST *table, const char *wild);
@@ -418,6 +419,8 @@ bool close_cached_tables(THD *thd, bool wait_for_refresh, TABLE_LIST *tables);
 void copy_field_from_tmp_record(Field *field,int offset);
 int fill_record(List<Item> &fields,List<Item> &values);
 int fill_record(Field **field,List<Item> &values);
+int list_open_tables(THD *thd,List<char> *files, const char *db,const char *wild);
+char* query_table_status(THD *thd,const char *db,const char *table_name);
 
 /* sql_calc.cc */
 bool eval_const_cond(COND *cond);

sql/sql_base.cc

@@ -112,6 +112,74 @@ static void check_unused(void)
 #define check_unused()
 #endif
 
+int list_open_tables(THD *thd,List<char> *tables, const char *db,const char *wild)
+{
+  int result = 0;
+  uint col_access=thd->col_access;
+  TABLE_LIST table_list;
+  DBUG_ENTER("list_open_tables");
+  VOID(pthread_mutex_lock(&LOCK_open));
+  bzero((char*) &table_list,sizeof(table_list));
+
+  for (uint idx=0 ; result == 0 && idx < open_cache.records; idx++)
+  {
+    TABLE *entry=(TABLE*) hash_element(&open_cache,idx);
+    if ((!entry->real_name) || strcmp(entry->table_cache_key,db))
+      continue;
+    if (wild && wild[0] && wild_compare(entry->real_name,wild))
+      continue;
+    if (db && !(col_access & TABLE_ACLS))
+    {
+      table_list.db= (char*) db;
+      table_list.real_name= entry->real_name;/*real name*/
+      table_list.grant.privilege=col_access;
+      if (check_grant(thd,TABLE_ACLS,&table_list,1))
+        continue;
+    }
+    /* need to check if he have't already listed it */
+
+    List_iterator<char> it(*tables);
+    char *table_name; 
+    int check = 0;
+    while (check == 0 && (table_name=it++))
+    {
+      if (!strcmp(table_name,entry->real_name))
+        check++;
+    }
+    if (check)
+      continue;
+    
+    if (tables->push_back(thd->strdup(entry->real_name)))
+    {
+      result = -1;
+    }
+  }
+  
+  VOID(pthread_mutex_unlock(&LOCK_open));
+  DBUG_RETURN(result);  
+}
+
+char*
+query_table_status(THD *thd,const char *db,const char *table_name)
+{
+  int cached = 0, in_use = 0;
+  char info[256];
+
+  for (uint idx=0 ; idx < open_cache.records; idx++)
+  {
+    TABLE *entry=(TABLE*) hash_element(&open_cache,idx);
+    if (strcmp(entry->table_cache_key,db) ||
+        strcmp(entry->real_name,table_name))
+      continue;
+
+    cached++;
+    if (entry->in_use)
+      in_use++;
+  }
+
+  sprintf(info, "cached=%d, in_use=%d", cached, in_use);
+  return thd->strdup(info);
+}
 
 
 /******************************************************************************

sql/sql_lex.h

@@ -52,7 +52,8 @@ enum enum_sql_command {
   SQLCOM_ROLLBACK, SQLCOM_COMMIT, SQLCOM_SLAVE_START, SQLCOM_SLAVE_STOP,
   SQLCOM_BEGIN, SQLCOM_LOAD_MASTER_TABLE, SQLCOM_CHANGE_MASTER,
   SQLCOM_RENAME_TABLE, SQLCOM_BACKUP_TABLE, SQLCOM_RESTORE_TABLE,
-  SQLCOM_RESET, SQLCOM_PURGE, SQLCOM_SHOW_BINLOGS
+  SQLCOM_RESET, SQLCOM_PURGE, SQLCOM_SHOW_BINLOGS,
+  SQLCOM_SHOW_OPEN_TABLES
 };
 
 enum lex_states { STATE_START, STATE_CHAR, STATE_IDENT,

sql/sql_parse.cc

@@ -1488,6 +1488,8 @@ mysql_execute_command(void)
     }
 #endif
   case SQLCOM_SHOW_TABLES:
+    /* FALL THROUGH */
+  case SQLCOM_SHOW_OPEN_TABLES:
 #ifdef DONT_ALLOW_SHOW_COMMANDS
     send_error(&thd->net,ER_NOT_ALLOWED_COMMAND);	/* purecov: inspected */
     DBUG_VOID_RETURN;
@@ -1508,7 +1510,10 @@ mysql_execute_command(void)
       if (check_access(thd,SELECT_ACL,db,&thd->col_access))
 	goto error;				/* purecov: inspected */
       /* grant is checked in mysqld_show_tables */
-      if (lex->options & SELECT_DESCRIBE)
+      if (lex->sql_command == SQLCOM_SHOW_OPEN_TABLES)
+        res= mysqld_show_open_tables(thd,db,
+				     (lex->wild ? lex->wild->ptr() : NullS));
+      else if (lex->options & SELECT_DESCRIBE)
         res= mysqld_extend_show_tables(thd,db,
 				     (lex->wild ? lex->wild->ptr() : NullS));
       else

sql/sql_show.cc

@@ -86,6 +86,47 @@ mysqld_show_dbs(THD *thd,const char *wild)
   DBUG_RETURN(0);
 }
 
+/***************************************************************************
+** List all open tables in a database
+***************************************************************************/
+
+int mysqld_show_open_tables(THD *thd,const char *db,const char *wild)
+{
+  Item_string *field=new Item_string("",0);
+  List<Item> field_list;
+  char *end,*table_name;
+  List<char> tables;
+  DBUG_ENTER("mysqld_show_open_tables");
+
+  field->name=(char*) thd->alloc(20+(uint) strlen(db)+(wild ? (uint) strlen(wild)+4:0));
+  end=strxmov(field->name,"Open_tables_in_",db,NullS);
+  if (wild && wild[0])
+    strxmov(end," (",wild,")",NullS);
+  field->max_length=NAME_LEN;
+  field_list.push_back(field);
+  field_list.push_back(new Item_empty_string("Comment",80));
+
+  if (send_fields(thd,field_list,1))
+    DBUG_RETURN(1);
+    
+  if (list_open_tables(thd,&tables,db,wild))
+    DBUG_RETURN(-1);
+
+  List_iterator<char> it(tables);
+  while ((table_name=it++))
+  {
+    thd->packet.length(0);
+    net_store_data(&thd->packet,table_name);
+    net_store_data(&thd->packet,query_table_status(thd,db,table_name));
+    if (my_net_write(&thd->net,(char*) thd->packet.ptr(),thd->packet.length()))
+      DBUG_RETURN(-1);
+  }
+
+
+  send_eof(&thd->net);
+  DBUG_RETURN(0);
+}
+
 /***************************************************************************
 ** List all tables in a database (fast version)
 ** A table is a .frm file in the current databasedir
@@ -161,9 +202,9 @@ mysql_find_files(THD *thd,List<char> *files, const char *db,const char *path,
     }
     else
     {
-        // Return only .frm files which isn't temp files.
+        // Return only .frm files which aren't temp files.
       if (my_strcasecmp(ext=fn_ext(file->name),reg_ext) ||
-          is_prefix(file->name,tmp_file_prefix))        // Mysql temp table
+          is_prefix(file->name,tmp_file_prefix))
         continue;
       *ext=0;
       if (wild && wild[0] && wild_compare(file->name,wild))

sql/sql_yacc.yy

@@ -216,6 +216,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 %token	NULL_SYM
 %token	NUM
 %token	ON
+%token	OPEN_SYM
 %token	OPTION
 %token	OPTIONALLY
 %token	OR
@@ -2151,6 +2152,11 @@ show_param:
 	    Lex->options|= SELECT_DESCRIBE;
 	    Lex->db= $3;
 	  }
+	| OPEN_SYM TABLES opt_db wild
+	  { Lex->sql_command= SQLCOM_SHOW_OPEN_TABLES;
+	    Lex->db= $3;
+	    Lex->options=0;
+	  }
 	| COLUMNS FROM table_ident opt_db wild
 	  {
 	    Lex->sql_command= SQLCOM_SHOW_FIELDS;
@@ -2513,6 +2519,7 @@ keyword:
 	| NATIONAL_SYM		{}
 	| NCHAR_SYM		{}
 	| NO_SYM		{}
+	| OPEN_SYM		{}
 	| PACK_KEYS_SYM		{}
 	| PASSWORD		{}
 	| PROCESS		{}