MDEV-12459 post-review fixes

* IS_USER_TEMP_TABLE() was misleading, name didn't match the code
* list of temp tables was rescanned number_of_databases times
* some temporary tables were not shown (from nonexistent databases)
* some temporary tables were shown more than once (e.g. after self-joins)
* sys.table_exists() - avoid querying I_S twice
* fix handling of temporary MERGE tables - it's pointless to fully open
  them, they're not in thd->temporary_tables, so they simply fail to
  open and are skipped. Relax the assertion instead.

mysql-test/main/information_schema_temp_table.result

@@ -200,17 +200,34 @@ show index in t;
 Table	Non_unique	Key_name	Seq_in_index	Column_name	Collation	Cardinality	Sub_part	Packed	Null	Index_type	Comment	Index_comment	Ignored
 t	1	b	1	b	A	NULL	NULL	NULL	YES	BTREE			NO
 drop database mysqltest;
+use test;
+show full tables;
+Tables_in_test	Table_type
+tmp_innodb_in_test	TEMPORARY TABLE
+select * from tmp_innodb_in_test, tmp_innodb_in_test x;
+a	a
+show full tables;
+Tables_in_test	Table_type
+tmp_innodb_in_test	TEMPORARY TABLE
+drop temporary tables tmp_innodb_in_test;
+create temporary table foo.t1 (a int);
+select table_schema, table_name from information_schema.tables where table_type='temporary';
+table_schema	table_name
+foo	t1
+mysqltest	tmp_table
+mysqltest	t
+my_db	t_temp
+drop temporary table foo.t1;
 #
 # MDEV-28351 Assertion `this->file->children_attached' failed in ha_myisammrg::info
 #
-use test;
 CREATE TABLE t1 (a INT) ENGINE=MyISAM;
 insert into t1 values (1);
 CREATE TEMPORARY TABLE t2 (a INT) ENGINE=MERGE UNION=(t1);
 CREATE TABLE t3 (a INT) ENGINE=MERGE UNION=(t1);
 SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'test';
 TABLE_CATALOG	TABLE_SCHEMA	TABLE_NAME	TABLE_TYPE	ENGINE	VERSION	ROW_FORMAT	TABLE_ROWS	AVG_ROW_LENGTH	DATA_LENGTH	MAX_DATA_LENGTH	INDEX_LENGTH	DATA_FREE	AUTO_INCREMENT	CREATE_TIME	UPDATE_TIME	CHECK_TIME	TABLE_COLLATION	CHECKSUM	CREATE_OPTIONS	TABLE_COMMENT	MAX_INDEX_LENGTH	TEMPORARY
-def	test	tmp_innodb_in_test	TEMPORARY	InnoDB	10	Dynamic	0	0	X	X	X	X	NULL	X	X	NULL	latin1_swedish_ci	NULL			X	Y
-def	test	t3	BASE TABLE	MRG_MyISAM	10	Fixed	1	5	X	X	X	X	NULL	X	X	NULL	latin1_swedish_ci	NULL			X	N
 def	test	t1	BASE TABLE	MyISAM	10	Fixed	1	7	X	X	X	X	NULL	X	X	NULL	latin1_swedish_ci	NULL			X	N
+def	test	t2	TEMPORARY	MRG_MyISAM	10	Fixed	0	0	X	X	X	X	NULL	X	X	NULL	latin1_swedish_ci	NULL			X	Y
+def	test	t3	BASE TABLE	MRG_MyISAM	10	Fixed	1	5	X	X	X	X	NULL	X	X	NULL	latin1_swedish_ci	NULL			X	N
 DROP TABLE t1,t2,t3;

mysql-test/main/information_schema_temp_table.test

@@ -195,15 +195,27 @@ show index in t;
 
 # Cleanup
 drop database mysqltest;
+use test;
+
+# many instances of the table temp table:
+show full tables;
+select * from tmp_innodb_in_test, tmp_innodb_in_test x;
+show full tables;
+drop temporary tables tmp_innodb_in_test;
+
+# non-existent db
+create temporary table foo.t1 (a int); # yup, that works
+select table_schema, table_name from information_schema.tables where table_type='temporary';
+drop temporary table foo.t1;
 
 --echo #
 --echo # MDEV-28351 Assertion `this->file->children_attached' failed in ha_myisammrg::info
 --echo #
-use test;
 CREATE TABLE t1 (a INT) ENGINE=MyISAM;
 insert into t1 values (1);
 CREATE TEMPORARY TABLE t2 (a INT) ENGINE=MERGE UNION=(t1);
 CREATE TABLE t3 (a INT) ENGINE=MERGE UNION=(t1);
+--sorted_result
 --replace_column 10 X 11 X 12 X 13 X 15 X 16 X 22 X
 SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'test';
 DROP TABLE t1,t2,t3;

mysql-test/suite/engines/funcs/r/rpl_row_drop.result

@@ -6,6 +6,7 @@ CREATE TABLE t2 (a int);
 CREATE TEMPORARY TABLE t2 (a int, b int);
 SHOW TABLES;
 Tables_in_test
+t2
 t1
 t2
 connection slave;
@@ -28,6 +29,7 @@ connection master;
 CREATE TEMPORARY TABLE t2 (a int, b int);
 SHOW TABLES;
 Tables_in_test
+t2
 t1
 t2
 connection slave;

scripts/sys_schema/procedures/table_exists.sql

@@ -154,21 +154,18 @@ BEGIN
     DECLARE db_quoted VARCHAR(64);
     DECLARE table_quoted VARCHAR(64);
     DECLARE v_table_type VARCHAR(30) DEFAULT '';
-    DECLARE v_table_type_num INT;
     DECLARE CONTINUE HANDLER FOR 1050 SET v_error = TRUE;
     DECLARE CONTINUE HANDLER FOR 1146 SET v_error = TRUE;
 
     -- First check do we have multiple rows, what can happen if temporary table
     -- and/or sequence is shadowing base table for example.
     -- In such scenario return temporary.
-    SET v_table_type_num = (SELECT COUNT(TABLE_TYPE) FROM information_schema.TABLES WHERE
+    SET v_table_type = (SELECT GROUP_CONCAT(TABLE_TYPE) FROM information_schema.TABLES WHERE
                             TABLE_SCHEMA = in_db AND TABLE_NAME = in_table);
 
-    IF v_table_type_num > 1 THEN
+    IF v_table_type LIKE '%,%' THEN
         SET out_exists = 'TEMPORARY';
     ELSE
-        SET v_table_type = (SELECT TABLE_TYPE FROM information_schema.TABLES WHERE
-                                TABLE_SCHEMA = in_db AND TABLE_NAME = in_table);
         IF v_table_type is NULL
         THEN
             SET v_table_type='';

sql/sql_base.cc

@@ -4764,10 +4764,10 @@ restart:
   {
     TABLE *tbl= tables->table;
 
+    /* Schema tables may not have a TABLE object here. */
     if (!tbl)
       continue;
 
-    /* Schema tables may not have a TABLE object here. */
     if (tbl->file->ha_table_flags() & HA_CAN_MULTISTEP_MERGE)
     {
       /* MERGE tables need to access parent and child TABLE_LISTs. */

sql/sql_show.cc

@@ -70,7 +70,6 @@
 
 #include "lex_symbol.h"
 #define KEYWORD_SIZE 64
-#define IS_USER_TEMP_TABLE(A) (A->tmp_table != NO_TMP_TABLE)
 
 extern SYMBOL symbols[];
 extern size_t symbols_length;
@@ -5310,15 +5309,58 @@ int get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)
     goto err;
   }
 
+  /* Use tmp_mem_root to allocate data for opened tables */
+  init_alloc_root(PSI_INSTRUMENT_ME, &tmp_mem_root, SHOW_ALLOC_BLOCK_SIZE,
+                  SHOW_ALLOC_BLOCK_SIZE, MY_THREAD_SPECIFIC);
+
+  /*
+    Separate handling for session temporary tables from the backup state
+    for table IS.tables and SHOW TABLES commands.
+  */
+  if ((schema_table_idx == SCH_TABLES || schema_table_idx == SCH_TABLE_NAMES) &&
+      open_tables_state_backup.temporary_tables)
+  {
+    All_tmp_tables_list::Iterator it(*open_tables_state_backup.temporary_tables);
+    TMP_TABLE_SHARE *share_temp;
+    const char *lookup_db= plan->lookup_field_vals.db_value.str;
+    int (*cmp)(CHARSET_INFO *, const char *, const char *)=
+      plan->lookup_field_vals.wild_db_value
+      ? wild_case_compare : system_charset_info->coll->strcasecmp;
+    while ((share_temp= it++))
+    {
+      if (lookup_db)
+      {
+        if (cmp(system_charset_info, share_temp->db.str, lookup_db))
+          continue;
+      }
+
+      TABLE *tmp_tbl= share_temp->all_tmp_tables.front();
+      if (schema_table_idx == SCH_TABLE_NAMES)
+      {
+        LEX_CSTRING *table_name= &tmp_tbl->s->table_name;
+        restore_record(table, s->default_values);
+        table->field[1]->store(share_temp->db.str, share_temp->db.length,
+                               system_charset_info);
+        table->field[2]->store(table_name->str, table_name->length,
+                               system_charset_info);
+        if (tmp_tbl->s->table_type == TABLE_TYPE_SEQUENCE)
+          table->field[3]->store(STRING_WITH_LEN("TEMPORARY SEQUENCE"),
+                                 system_charset_info);
+        else
+          table->field[3]->store(STRING_WITH_LEN("TEMPORARY TABLE"),
+                                 system_charset_info);
+        schema_table_store_record(thd, table);
+      }
+      else /* SCH_TABLE */
+        process_i_s_table_temporary_tables(thd, table, tmp_tbl);
+    }
+  }
+
   bzero((char*) &table_acl_check, sizeof(table_acl_check));
 
   if (make_db_list(thd, &db_names, &plan->lookup_field_vals))
     goto err;
 
-  /* Use tmp_mem_root to allocate data for opened tables */
-  init_alloc_root(PSI_INSTRUMENT_ME, &tmp_mem_root, SHOW_ALLOC_BLOCK_SIZE,
-                  SHOW_ALLOC_BLOCK_SIZE, MY_THREAD_SPECIFIC);
-
   for (size_t i=0; i < db_names.elements(); i++)
   {
     LEX_CSTRING *db_name= db_names.at(i);
@@ -5333,64 +5375,6 @@ int get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)
     {
       Dynamic_array<LEX_CSTRING*> table_names(PSI_INSTRUMENT_MEM);
 
-      /* Separate handling for session temporary tables from the backup state
-         for table IS.tables and SHOW TABLES commands.
-      */
-      if ((schema_table_idx == SCH_TABLES || schema_table_idx == SCH_TABLE_NAMES) &&
-          open_tables_state_backup.temporary_tables)
-      {
-        All_tmp_tables_list::Iterator it(*open_tables_state_backup.temporary_tables);
-        TMP_TABLE_SHARE *share_temp;
-        while ((share_temp= it++))
-        {
-          DBUG_ASSERT(IS_USER_TEMP_TABLE(share_temp));
-          if (my_strcasecmp(system_charset_info, db_name->str,
-                            share_temp->db.str))
-            continue;
-
-          All_share_tables_list::Iterator it2(share_temp->all_tmp_tables);
-          while (TABLE *tmp_tbl= it2++)
-          {
-            if (schema_table_idx == SCH_TABLE_NAMES)
-            {
-              LEX_CSTRING *table_name= &tmp_tbl->s->table_name;
-              restore_record(table, s->default_values);
-              table->field[schema_table->idx_field1]->
-                store(db_name->str, db_name->length, system_charset_info);
-              table->field[schema_table->idx_field2]->
-                store(table_name->str, table_name->length,
-                      system_charset_info);
-              if (tmp_tbl->s->table_type == TABLE_TYPE_SEQUENCE)
-                table->field[3]->store(STRING_WITH_LEN("TEMPORARY SEQUENCE"),
-                                       system_charset_info);
-              else
-                table->field[3]->store(STRING_WITH_LEN("TEMPORARY TABLE"),
-                                       system_charset_info);
-              schema_table_store_record(thd, table);
-            }
-            else /* SCH_TABLE */
-            {
-              if (tmp_tbl->file->ha_table_flags() & HA_CAN_MULTISTEP_MERGE)
-              {
-                /*
-                  MyISAM MERGE table. We have to to call open on it and its
-                  children
-                */
-                LEX_CSTRING table_name=
-                  { tmp_tbl->alias.ptr(), tmp_tbl->alias.length() };
-                if (fill_schema_table_by_open(thd, &tmp_mem_root, FALSE,
-                                              table, schema_table,
-                                              &tmp_tbl->s->db, &table_name,
-                                              &open_tables_state_backup,
-                                              0))
-                  goto err;
-              }
-              else
-                process_i_s_table_temporary_tables(thd, table, tmp_tbl);
-            }
-          }
-        }
-      }
       int res= make_table_name_list(thd, &table_names, lex,
                                     &plan->lookup_field_vals, db_name);
       if (unlikely(res == 2))   /* Not fatal error, continue */
@@ -5655,11 +5639,11 @@ static int get_schema_tables_record(THD *thd, TABLE_LIST *tables,
 
     if (share->tmp_table == SYSTEM_TMP_TABLE)
       table->field[3]->store(STRING_WITH_LEN("SYSTEM VIEW"), cs);
-    else if (IS_USER_TEMP_TABLE(share) && share->table_type == TABLE_TYPE_SEQUENCE)
+    else if (share->tmp_table && share->table_type == TABLE_TYPE_SEQUENCE)
       table->field[3]->store(STRING_WITH_LEN("TEMPORARY SEQUENCE"), cs);
     else if (share->table_type == TABLE_TYPE_SEQUENCE)
       table->field[3]->store(STRING_WITH_LEN("SEQUENCE"), cs);
-    else if (IS_USER_TEMP_TABLE(share))
+    else if (share->tmp_table)
       table->field[3]->store(STRING_WITH_LEN("TEMPORARY"), cs);
     else
     {

storage/myisammrg/ha_myisammrg.cc

@@ -1273,7 +1273,6 @@ int ha_myisammrg::delete_all_rows()
 int ha_myisammrg::info(uint flag)
 {
   MYMERGE_INFO mrg_info;
-  DBUG_ASSERT(this->file->children_attached);
   (void) myrg_status(file,&mrg_info,flag);
   /*
     The following fails if one has not compiled MySQL with -DBIG_TABLES

storage/myisammrg/myrg_info.c

@@ -44,42 +44,45 @@ int myrg_status(MYRG_INFO *info,register MYMERGE_INFO *x,int flag)
     MYRG_TABLE *file;
 
     info->records=info->del=info->data_file_length=0;
-    for (file=info->open_tables ; file != info->end_table ; file++)
+    if (likely(info->children_attached))
     {
-      file->file_offset=info->data_file_length;
+      for (file=info->open_tables ; file != info->end_table ; file++)
-      info->data_file_length+=file->table->s->state.state.data_file_length;
+      {
-      info->records+=file->table->s->state.state.records;
+        file->file_offset=info->data_file_length;
-      info->del+=file->table->s->state.state.del;
+        info->data_file_length+=file->table->s->state.state.data_file_length;
-      DBUG_PRINT("info2",("table: %s, offset: %lu",
+        info->records+=file->table->s->state.state.records;
-                  file->table->filename,(ulong) file->file_offset));
+        info->del+=file->table->s->state.state.del;
+        DBUG_PRINT("info2",("table: %s, offset: %lu",
+                    file->table->filename,(ulong) file->file_offset));
+      }
+      if (current_table)
+      {
+        /*
+          errkey is set to the index number of the myisam tables. But
+          since the MERGE table can have less keys than the MyISAM
+          tables, errkey cannot be be used as an index into the key_info
+          on the server. This value will be overwritten with MAX_KEY by
+          the MERGE engine.
+        */
+        x->errkey= current_table->table->errkey;
+        /*
+          Calculate the position of the duplicate key to be the sum of the
+          offset of the myisam file and the offset into the file at which
+          the duplicate key is located.
+        */
+        x->dupp_key_pos= current_table->file_offset + current_table->table->dupp_key_pos;
+      }
+      else
+      {
+        x->errkey= 0;
+        x->dupp_key_pos= 0;
+      }
     }
     x->records= info->records;
     x->deleted= info->del;
     x->data_file_length= info->data_file_length;
     x->reclength= info->reclength;
     x->options= info->options;
-    if (current_table)
-    {
-      /*
-        errkey is set to the index number of the myisam tables. But
-        since the MERGE table can have less keys than the MyISAM
-        tables, errkey cannot be be used as an index into the key_info
-        on the server. This value will be overwritten with MAX_KEY by
-        the MERGE engine.
-      */
-      x->errkey= current_table->table->errkey;
-      /*
-        Calculate the position of the duplicate key to be the sum of the
-        offset of the myisam file and the offset into the file at which
-        the duplicate key is located.
-      */
-      x->dupp_key_pos= current_table->file_offset + current_table->table->dupp_key_pos;
-    }
-    else
-    {
-      x->errkey= 0;
-      x->dupp_key_pos= 0;
-    }
     x->rec_per_key = info->rec_per_key_part;
   }
   DBUG_RETURN(0);