MDEV-5103: server crashed on singular Item_equal

Singular Item_equal support added.

The problem was that during constant table substitution Item_equal become containing only one constant which was not supported internally.

mysql-test/r/func_equal.result

@@ -42,3 +42,47 @@ select * from t1 where a in ('4828532208463511553');
 a
 4828532208463511553
 drop table t1;
+#End of 4.1 tests
+#
+# MDEV-5103: server crashed on singular Item_equal
+#
+CREATE TABLE `t1` (
+`tipo` enum('p','r') NOT NULL DEFAULT 'r',
+`arquivo_id` bigint(20) unsigned NOT NULL DEFAULT '0',
+`arquivo_md5` char(32) NOT NULL,
+`conteudo` longblob NOT NULL,
+`usuario` varchar(15) NOT NULL,
+`datahora_gmt` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
+`tipo_arquivo` varchar(255) NOT NULL,
+`nome_arquivo` varchar(255) NOT NULL,
+`tamanho_arquivo` bigint(20) unsigned NOT NULL DEFAULT '0',
+PRIMARY KEY (`tipo`,`arquivo_id`),
+UNIQUE KEY `tipo` (`tipo`,`arquivo_md5`)
+) ENGINE=Aria DEFAULT CHARSET=latin1 PAGE_CHECKSUM=1;
+INSERT INTO `t1` (`tipo`, `arquivo_id`, `arquivo_md5`, `conteudo`, `usuario`, `datahora_gmt`, `tipo_arquivo`, `nome_arquivo`, `tamanho_arquivo`) VALUES
+('r', 1, 'ad18832202b199728921807033a8a515', '', 'rspadim', '2013-10-05 13:55:50', '001_cbr643', 'CBR6431677410201314132.ret', 21306);
+CREATE TABLE `t2` (
+`tipo` enum('p','r') NOT NULL DEFAULT 'p',
+`arquivo_id` bigint(20) NOT NULL DEFAULT '0',
+`usuario` varchar(25) NOT NULL,
+`datahora` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
+`erros` longblob NOT NULL,
+`importados` bigint(20) unsigned NOT NULL DEFAULT '0',
+`n_importados` bigint(20) unsigned NOT NULL DEFAULT '0',
+PRIMARY KEY (`tipo`,`arquivo_id`,`datahora`)
+) ENGINE=Aria DEFAULT CHARSET=latin1 PAGE_CHECKSUM=1;
+INSERT INTO `t2` (`tipo`, `arquivo_id`, `usuario`, `datahora`, `erros`, `importados`, `n_importados`) VALUES
+('r', 1, 'rspadim', '2013-10-05 14:25:30', '', 32, 0);
+SELECT
+arquivo_id,usuario,datahora_gmt,tipo_arquivo,nome_arquivo,tamanho_arquivo
+FROM t1 AS a
+WHERE datahora_gmt>='0000-00-00 00:00:00' AND
+datahora_gmt<='2013-10-07 02:59:59' AND tipo='r' AND
+(tipo_arquivo,arquivo_id) NOT IN
+(SELECT tipo_arquivo,arquivo_id
+FROM t2
+WHERE (tipo_arquivo,arquivo_id)=(a.tipo_arquivo,a.arquivo_id))
+ORDER BY arquivo_id DESC;
+arquivo_id	usuario	datahora_gmt	tipo_arquivo	nome_arquivo	tamanho_arquivo
+drop table t2, t1;
+#End of 5.3 tests

mysql-test/t/func_equal.test

@@ -43,4 +43,54 @@ select * from t1 where a = '4828532208463511553';
 select * from t1 where a in ('4828532208463511553');
 drop table t1;
 
-# End of 4.1 tests
+--echo #End of 4.1 tests
+
+--echo #
+--echo # MDEV-5103: server crashed on singular Item_equal
+--echo #
+
+CREATE TABLE `t1` (
+  `tipo` enum('p','r') NOT NULL DEFAULT 'r',
+  `arquivo_id` bigint(20) unsigned NOT NULL DEFAULT '0',
+  `arquivo_md5` char(32) NOT NULL,
+  `conteudo` longblob NOT NULL,
+  `usuario` varchar(15) NOT NULL,
+  `datahora_gmt` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
+  `tipo_arquivo` varchar(255) NOT NULL,
+  `nome_arquivo` varchar(255) NOT NULL,
+  `tamanho_arquivo` bigint(20) unsigned NOT NULL DEFAULT '0',
+  PRIMARY KEY (`tipo`,`arquivo_id`),
+  UNIQUE KEY `tipo` (`tipo`,`arquivo_md5`)
+) ENGINE=Aria DEFAULT CHARSET=latin1 PAGE_CHECKSUM=1;
+
+INSERT INTO `t1` (`tipo`, `arquivo_id`, `arquivo_md5`, `conteudo`, `usuario`, `datahora_gmt`, `tipo_arquivo`, `nome_arquivo`, `tamanho_arquivo`) VALUES
+	('r', 1, 'ad18832202b199728921807033a8a515', '', 'rspadim', '2013-10-05 13:55:50', '001_cbr643', 'CBR6431677410201314132.ret', 21306);
+
+
+CREATE TABLE `t2` (
+  `tipo` enum('p','r') NOT NULL DEFAULT 'p',
+  `arquivo_id` bigint(20) NOT NULL DEFAULT '0',
+  `usuario` varchar(25) NOT NULL,
+  `datahora` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
+  `erros` longblob NOT NULL,
+  `importados` bigint(20) unsigned NOT NULL DEFAULT '0',
+  `n_importados` bigint(20) unsigned NOT NULL DEFAULT '0',
+  PRIMARY KEY (`tipo`,`arquivo_id`,`datahora`)
+) ENGINE=Aria DEFAULT CHARSET=latin1 PAGE_CHECKSUM=1;
+
+INSERT INTO `t2` (`tipo`, `arquivo_id`, `usuario`, `datahora`, `erros`, `importados`, `n_importados`) VALUES
+	('r', 1, 'rspadim', '2013-10-05 14:25:30', '', 32, 0);
+
+SELECT
+arquivo_id,usuario,datahora_gmt,tipo_arquivo,nome_arquivo,tamanho_arquivo
+  FROM t1 AS a
+  WHERE datahora_gmt>='0000-00-00 00:00:00' AND
+    datahora_gmt<='2013-10-07 02:59:59' AND tipo='r' AND
+    (tipo_arquivo,arquivo_id) NOT IN
+      (SELECT tipo_arquivo,arquivo_id
+        FROM t2
+        WHERE (tipo_arquivo,arquivo_id)=(a.tipo_arquivo,a.arquivo_id))
+  ORDER BY arquivo_id DESC;
+
+drop table t2, t1;
+--echo #End of 5.3 tests

sql/item_cmpfunc.cc

@@ -5564,6 +5564,12 @@ void Item_equal::add_const(Item *c, Item *f)
     func->quick_fix_field();
     cond_false= !func->val_int();
   }
+  /*
+    TODO: also support the case where Item_equal becomes singular with
+    this->is_cond_true()=1.  When I attempted to mark the item as constant,
+    the optimizer attempted to remove it, however it is still referenced from
+    COND_EQUAL and I got a crash.
+  */
   if (cond_false)
     const_item_cache= 1;
 }
@@ -5768,7 +5774,8 @@ void Item_equal::merge_into_list(List<Item_equal> *list,
 
 void Item_equal::sort(Item_field_cmpfunc compare, void *arg)
 {
-  bubble_sort<Item>(&equal_items, compare, arg);
+  if (equal_items.elements > 1)
+    bubble_sort<Item>(&equal_items, compare, arg);
 }
 
 
@@ -5868,6 +5875,12 @@ bool Item_equal::fix_fields(THD *thd, Item **ref)
 void Item_equal::update_used_tables()
 {
   not_null_tables_cache= used_tables_cache= 0;
+  /*
+    TODO: also support the case where Item_equal becomes singular with
+    this->is_cond_true()=1.  When I attempted to mark the item as constant,
+    the optimizer attempted to remove it, however it is still referenced from
+    COND_EQUAL and I got a crash.
+  */
   if ((const_item_cache= cond_false))
     return;
   Item_equal_fields_iterator it(*this);
@@ -5916,6 +5929,8 @@ longlong Item_equal::val_int()
 {
   if (cond_false)
     return 0;
+  if (is_cond_true())
+    return 1;
   Item *item= get_const();
   Item_equal_fields_iterator it(*this);
   if (!item)
@@ -5940,6 +5955,11 @@ longlong Item_equal::val_int()
 void Item_equal::fix_length_and_dec()
 {
   Item *item= get_first(NO_PARTICULAR_TAB, NULL);
+  if (!item)
+  {
+    DBUG_ASSERT(is_cond_true()); // it should be the only constant
+    item= equal_items.head();
+  }
   eval_item= cmp_item::get_comparator(item->cmp_type(), item,
                                       item->collation.collation);
 }

sql/item_cmpfunc.h

@@ -1725,6 +1725,7 @@ class Item_equal: public Item_bool_func
   Item_equal(Item_equal *item_equal);
   /* Currently the const item is always the first in the list of equal items */
   inline Item* get_const() { return with_const ? equal_items.head() : NULL; }
+  inline bool is_cond_true() { return equal_items.elements == 1; }
   void add_const(Item *c, Item *f = NULL);
   /** Add a non-constant item to the multiple equality */
   void add(Item *f) { equal_items.push_back(f); }