merged

Docs/manual.texi

@@ -51770,6 +51770,8 @@ not yet 100% confident in this code.
 Allow one to start multiple MySQL servers on windows (code backported
 from 4.0.2).
 @item
+Fixed that @code{--core-file} works on Linux (at least on kernel 2.4.18).
+@item
 Fixed a problem with BDB and @code{ALTER TABLE}.
 @item
 Fixed reference to freed memory when doing complicated @code{GROUP BY
@@ -51855,6 +51857,11 @@ Changed initialisation of @code{RND()} to make it less predicatable.
 Fixed problem with @code{GROUP BY} on result with expression that created a
 @code{BLOB} field.
 @item
+Fixed problem with @code{GROUP BY} on columns that have NULL values.  To
+solve this we now create an MyISAM temporary table when doing a group by
+on a possible NULL item.  In MySQL 4.0.5 we can again use in memory HEAP
+tables for this case.
+@item
 Fixed problem with privilege tables when downgrading from 4.0.2 to 3.23.
 @item
 Fixed thread bug in @code{SLAVE START}, @code{SLAVE STOP} and automatic repair

mysql-test/t/merge.test

@@ -185,3 +185,22 @@ CREATE TABLE t (  a int(11) NOT NULL default '0',  b int(11) NOT NULL default '0
 select max(b) from t where a = 2;
 select max(b) from t1 where a = 2;
 drop table if exists t,t1,t2;
+
+#
+# temporary merge tables
+#
+drop table if exists t1, t2, t3, t4, t5, t6;
+create table t1 (a int not null);
+create table t2 (a int not null);
+insert into t1 values (1);
+insert into t2 values (2);
+create temporary table t3 (a int not null) TYPE=MERGE UNION=(t1,t2);
+select * from t3;
+create temporary table t4 (a int not null);
+create temporary table t5 (a int not null);
+insert into t4 values (1);
+insert into t5 values (2);
+create temporary table t6 (a int not null) TYPE=MERGE UNION=(t4,t5);
+select * from t6;
+drop table if exists t1, t2, t3, t4, t5, t6;
+

sql/ha_myisammrg.cc

@@ -371,7 +371,28 @@ int ha_myisammrg::create(const char *name, register TABLE *form,
 					sizeof(char*))))
     DBUG_RETURN(1);
   for (pos=table_names ; tables ; tables=tables->next)
-    *pos++= tables->real_name;
+  {
+    char *table_name;
+    if (create_info->options & HA_LEX_CREATE_TMP_TABLE)
+    {
+      TABLE **tbl=find_temporary_table(current_thd,
+          tables->db, tables->real_name);
+      if (!tbl)
+      {
+        table_name=sql_alloc(1+
+            my_snprintf(buff,FN_REFLEN,"%s/%s/%s",mysql_real_data_home,
+                        tables->db, tables->real_name));
+        if (!table_name)
+          DBUG_RETURN(1);
+        strcpy(table_name, buff);
+      }
+      else
+        table_name=(*tbl)->path;
+    }
+    else
+      table_name=tables->real_name;
+    *pos++= table_name;
+  }
   *pos=0;
   DBUG_RETURN(myrg_create(fn_format(buff,name,"","",2+4+16),
 			  (const char **) table_names,

sql/mysqld.cc

@@ -1404,7 +1404,11 @@ information that should help you find out what is causing the crash.\n");
 #endif /* HAVE_STACKTRACE */
 
  if (test_flags & TEST_CORE_ON_SIGNAL)
+ {
+   fprintf(stderr, "Writing a core file\n");
+   fflush(stderr);
    write_core(sig);
+ }
  exit(1);
 }
 

sql/stacktrace.c

@@ -206,7 +206,7 @@ resolve it\n");
 
 /* Produce a core for the thread */
 
-#ifdef HAVE_LINUXTHREADS
+#ifdef NOT_USED /* HAVE_LINUXTHREADS */
 void write_core(int sig)
 {
   signal(sig, SIG_DFL);