MDEV-24593 Signal 11 when group by primary key of table joined to information_schema.columns

I_S tables were materialized too late, an attempt to use table
statistics before the table was created caused a crash.

Let's move table creation up. it only needs read_set to
be calculated properly, this happens in JOIN::optimize_inner(),
after semijoin transformation.

Note that tables are not populated at that point, so most of the
statistics would make no sense anyway. But at least field sizes
will be correct. And it won't crash.

3 files changed, 58 insertions, 47 deletions

diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 203422f0b43..8baac124b71 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -1556,7 +1556,7 @@ int JOIN::init_join_caches()
 int
 JOIN::optimize_inner()
 {
-  DBUG_ENTER("JOIN::optimize");
+  DBUG_ENTER("JOIN::optimize_inner");
   subq_exit_fl= false;
   do_send_rows = (unit->select_limit_cnt) ? 1 : 0;
 
@@ -1624,6 +1624,10 @@ JOIN::optimize_inner()
 
   table_count= select_lex->leaf_tables.elements;
 
+  if (select_lex->options & OPTION_SCHEMA_TABLE &&
+      optimize_schema_tables_memory_usage(select_lex->leaf_tables))
+    DBUG_RETURN(1);
+
   if (setup_ftfuncs(select_lex)) /* should be after having->fix_fields */
     DBUG_RETURN(-1);
 
diff --git a/sql/sql_show.cc b/sql/sql_show.cc
index f25a8861bc1..9a5141fa414 100644
--- a/sql/sql_show.cc
+++ b/sql/sql_show.cc
@@ -8658,55 +8658,64 @@ end:
 }
 
 
-static int optimize_schema_tables_memory_usage(TABLE_LIST *table_list)
+bool optimize_schema_tables_memory_usage(List<TABLE_LIST> &tables)
 {
-  TABLE *table= table_list->table;
-  THD *thd=table->in_use;
-  if (!table->is_created())
-  {
-    TMP_TABLE_PARAM *p= table_list->schema_table_param;
-    TMP_ENGINE_COLUMNDEF *from_recinfo, *to_recinfo;
-    DBUG_ASSERT(table->s->keys == 0);
-    DBUG_ASSERT(table->s->uniques == 0);
-
-    uchar *cur= table->field[0]->ptr;
-    /* first recinfo could be a NULL bitmap, not an actual Field */
-    from_recinfo= to_recinfo= p->start_recinfo + (cur != table->record[0]);
-    for (uint i=0; i < table->s->fields; i++, from_recinfo++)
-    {
-      Field *field= table->field[i];
-      DBUG_ASSERT(field->vcol_info == 0);
-      DBUG_ASSERT(from_recinfo->length);
-      DBUG_ASSERT(from_recinfo->length == field->pack_length_in_rec());
-      if (bitmap_is_set(table->read_set, i))
+  List_iterator<TABLE_LIST> tli(tables);
+
+  while (TABLE_LIST *table_list= tli++)
+  {
+    TABLE *table= table_list->table;
+    THD *thd=table->in_use;
+
+    if (!table_list->schema_table || !thd->fill_information_schema_tables())
+      continue;
+
+    if (!table->is_created())
+    {
+      TMP_TABLE_PARAM *p= table_list->schema_table_param;
+      TMP_ENGINE_COLUMNDEF *from_recinfo, *to_recinfo;
+      DBUG_ASSERT(table->s->keys == 0);
+      DBUG_ASSERT(table->s->uniques == 0);
+
+      uchar *cur= table->field[0]->ptr;
+      /* first recinfo could be a NULL bitmap, not an actual Field */
+      from_recinfo= to_recinfo= p->start_recinfo + (cur != table->record[0]);
+      for (uint i=0; i < table->s->fields; i++, from_recinfo++)
       {
-        field->move_field(cur);
-        *to_recinfo++= *from_recinfo;
-        cur+= from_recinfo->length;
+        Field *field= table->field[i];
+        DBUG_ASSERT(field->vcol_info == 0);
+        DBUG_ASSERT(from_recinfo->length);
+        DBUG_ASSERT(from_recinfo->length == field->pack_length_in_rec());
+        if (bitmap_is_set(table->read_set, i))
+        {
+          field->move_field(cur);
+          *to_recinfo++= *from_recinfo;
+          cur+= from_recinfo->length;
+        }
+        else
+        {
+          field= new (thd->mem_root) Field_string(cur, 0, field->null_ptr,
+                                field->null_bit, Field::NONE,
+                                &field->field_name, field->dtcollation());
+          field->init(table);
+          field->field_index= i;
+          DBUG_ASSERT(field->pack_length_in_rec() == 0);
+          table->field[i]= field;
+        }
       }
-      else
+      if ((table->s->reclength= (ulong)(cur - table->record[0])) == 0)
       {
-        field= new (thd->mem_root) Field_string(cur, 0, field->null_ptr,
-                              field->null_bit, Field::NONE,
-                              &field->field_name, field->dtcollation());
-        field->init(table);
-        field->field_index= i;
-        DBUG_ASSERT(field->pack_length_in_rec() == 0);
-        table->field[i]= field;
+        /* all fields were optimized away. Force a non-0-length row */
+        table->s->reclength= to_recinfo->length= 1;
+        to_recinfo++;
       }
-    }
-    if ((table->s->reclength= (ulong)(cur - table->record[0])) == 0)
-    {
-      /* all fields were optimized away. Force a non-0-length row */
-      table->s->reclength= to_recinfo->length= 1;
-      to_recinfo++;
-    }
-    p->recinfo= to_recinfo;
+      p->recinfo= to_recinfo;
 
-    // TODO switch from Aria to Memory if all blobs were optimized away?
-    if (instantiate_tmp_table(table, p->keyinfo, p->start_recinfo, &p->recinfo,
-                 table_list->select_lex->options | thd->variables.option_bits))
-      return 1;
+      // TODO switch from Aria to Memory if all blobs were optimized away?
+      if (instantiate_tmp_table(table, p->keyinfo, p->start_recinfo, &p->recinfo,
+                   table_list->select_lex->options | thd->variables.option_bits))
+        return 1;
+    }
   }
   return 0;
 }
@@ -8732,9 +8741,6 @@ bool optimize_schema_tables_reads(JOIN *join)
     TABLE_LIST *table_list= tab->table->pos_in_table_list;
     if (table_list->schema_table && thd->fill_information_schema_tables())
     {
-      if (optimize_schema_tables_memory_usage(table_list))
-        DBUG_RETURN(1);
-
       /* A value of 0 indicates a dummy implementation */
       if (table_list->schema_table->fill_table == 0)
         continue;
diff --git a/sql/sql_show.h b/sql/sql_show.h
index 39cbc35230a..c1845d8c1b3 100644
--- a/sql/sql_show.h
+++ b/sql/sql_show.h
@@ -238,6 +238,7 @@ public:
 };
 
 bool optimize_schema_tables_reads(JOIN *join);
+bool optimize_schema_tables_memory_usage(List<TABLE_LIST> &tables);
 
 /* Handle the ignored database directories list for SHOW/I_S. */
 bool ignore_db_dirs_init();