bk commit into 4.1 tree (bar:1.2467) BUG#10446

[bar]

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ChangeSet
  1.2467 05/11/21 17:26:31 bar@stripped +5 -0
    Bug#10446 Illegal mix of collations:
  item_strfunc.h, item_strfunc.cc, item.cc:
    Try to convert a const item into destination 
    character set. If conversion happens without
    data loss, then cache the converted value
    and return it during val_str().
    Otherwise, if conversion loses data, return
    Illeral mix of collations error, as it happened
    previously.
  ctype_recoding.result, ctype_recoding.test:
    Fixing tests accordingly.

  mysql-test/r/ctype_recoding.result
    1.25 05/11/21 17:23:50 bar@stripped +8 -1
    Fixing tests accordingly.

  mysql-test/t/ctype_recoding.test
    1.21 05/11/21 17:23:41 bar@stripped +9 -2
    Fixing tests accordingly.

  sql/item_strfunc.cc
    1.238 05/11/21 17:23:08 bar@stripped +2 -0
    Return cached value when it's possible.

  sql/item_strfunc.h
    1.99 05/11/21 17:22:56 bar@stripped +32 -2

  sql/item.cc
    1.229 05/11/21 17:20:38 bar@stripped +2 -10
    Bug#10446 Illegal mix of collations
    Try to convert a const item into destination 
    character set. If conversion happens without
    data loss, then cache the converted value
    and return it during val_str().
    Otherwise, if conversion loses data, return
    Illeral mix of collations error, as it happened
    previously.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	bar
# Host:	bar.intranet.mysql.r18.ru
# Root:	/usr/home/bar/mysql-4.1.b10446

--- 1.228/sql/item.cc	2005-10-25 21:01:39 +05:00
+++ 1.229/sql/item.cc	2005-11-21 17:20:38 +04:00
@@ -211,16 +211,8 @@
 
 Item *Item::safe_charset_converter(CHARSET_INFO *tocs)
 {
-  /*
-    Allow conversion from and to "binary".
-    Don't allow automatic conversion to non-Unicode charsets,
-    as it potentially loses data.
-  */
-  if (collation.collation != &my_charset_bin &&
-      tocs != &my_charset_bin &&
-      !(tocs->state & MY_CS_UNICODE))
-    return NULL; // safe conversion is not possible
-  return new Item_func_conv_charset(this, tocs);
+  Item_func_conv_charset *conv= new Item_func_conv_charset(this, tocs, 1);
+  return conv->safe ? conv : NULL;
 }
 
 

--- 1.237/sql/item_strfunc.cc	2005-10-07 04:15:50 +05:00
+++ 1.238/sql/item_strfunc.cc	2005-11-21 17:23:08 +04:00
@@ -2252,6 +2252,8 @@
 String *Item_func_conv_charset::val_str(String *str)
 {
   DBUG_ASSERT(fixed == 1);
+  if (use_cached_value)
+    return null_value ? 0 : &str_value;
   String *arg= args[0]->val_str(str);
   uint dummy_errors;
   if (!arg)

--- 1.98/sql/item_strfunc.h	2005-11-10 18:12:18 +04:00
+++ 1.99/sql/item_strfunc.h	2005-11-21 17:22:56 +04:00
@@ -614,10 +614,40 @@
 
 class Item_func_conv_charset :public Item_str_func
 {
+  bool use_cached_value;
 public:
+  bool safe;
   CHARSET_INFO *conv_charset; // keep it public
-  Item_func_conv_charset(Item *a, CHARSET_INFO *cs) :Item_str_func(a)
-  { conv_charset=cs; }
+  Item_func_conv_charset(Item *a, CHARSET_INFO *cs) :Item_str_func(a) 
+  { conv_charset= cs; use_cached_value= 0; safe= 0; }
+  Item_func_conv_charset(Item *a, CHARSET_INFO *cs, bool cache_if_const) 
+    :Item_str_func(a) 
+  {
+    DBUG_ASSERT(args[0]->fixed);
+    conv_charset= cs;
+    if (cache_if_const && args[0]->const_item())
+    {
+      uint errors= 0;
+      String tmp, *str= args[0]->val_str(&tmp);
+      if (!str || str_value.copy(str->ptr(), str->length(),
+                                 str->charset(), conv_charset, &errors))
+        null_value= 1;
+      use_cached_value= 1;
+      safe= (errors == 0);
+    }
+    else
+    {
+      use_cached_value= 0;
+      /*
+        Conversion from and to "binary" is safe.
+        Conversion to Unicode is safe.
+        Other kind of conversions are potentially lossy.
+      */
+      safe= (args[0]->collation.collation == &my_charset_bin ||
+             cs == &my_charset_bin ||
+             (cs->state & MY_CS_UNICODE));
+    }
+  }
   String *val_str(String *);
   void fix_length_and_dec();
   const char *func_name() const { return "convert"; }

--- 1.24/mysql-test/r/ctype_recoding.result	2004-11-02 16:01:13 +04:00
+++ 1.25/mysql-test/r/ctype_recoding.result	2005-11-21 17:23:50 +04:00
@@ -181,11 +181,18 @@
 a
-ERROR HY000: Illegal mix of collations (cp1251_general_ci,IMPLICIT) and (koi8r_general_ci,COERCIBLE) for operation '='
+a
 ERROR HY000: Illegal mix of collations (cp1251_general_ci,IMPLICIT) and (latin1_swedish_ci,COERCIBLE) for operation '='
 drop table t1;
 set names latin1;
+create table t1 (a char(10) character set utf8 collate utf8_bin);
+insert into t1 values ('       xxx');
+select * from t1 where a=lpad('xxx',10,' ');
+a
+       xxx
+drop table t1;
 set names koi8r;
 create table t1 (c1 char(10) character set cp1251);

--- 1.20/mysql-test/t/ctype_recoding.test	2005-07-28 05:21:40 +05:00
+++ 1.21/mysql-test/t/ctype_recoding.test	2005-11-21 17:23:41 +04:00
@@ -144,14 +144,21 @@
 # this is possible:
-# this is not possible, because we have a function, not just a constant:
---error 1267
+# this is possible, because we have a function with constant arguments:
 --error 1267
 drop table t1;
 set names latin1;
+
+#
+# Bug#10446 Illegal mix of collations
+#
+create table t1 (a char(10) character set utf8 collate utf8_bin);
+insert into t1 values ('       xxx');
+select * from t1 where a=lpad('xxx',10,' ');
+drop table t1;
 
 #
 # Check more automatic conversion