8 files changed, 149 insertions, 50 deletions

diff --git a/mysql-test/r/func_str.result b/mysql-test/r/func_str.result
index 2a2fe50ad0f..d144e84dfdc 100644
--- a/mysql-test/r/func_str.result
+++ b/mysql-test/r/func_str.result
@@ -2558,3 +2558,32 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	2	Using join buffer
 2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	2	
 drop table t1;
+#
+# Bug#49141: Encode function is significantly slower in 5.1 compared to 5.0
+#
+DROP TABLE IF EXISTS t1, t2;
+CREATE TABLE t1 (a VARCHAR(20), b INT);
+CREATE TABLE t2 (a VARCHAR(20), b INT);
+INSERT INTO t1 VALUES ('ABC', 1);
+INSERT INTO t2 VALUES ('ABC', 1);
+SELECT DECODE((SELECT ENCODE('secret', t1.a) FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b), t2.a)
+FROM t1,t2 WHERE t1.b = t1.b > 0 GROUP BY t2.b;
+DECODE((SELECT ENCODE('secret', t1.a) FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b), t2.a)
+secret
+SELECT DECODE((SELECT ENCODE('secret', 'ABC') FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b), t2.a)
+FROM t1,t2 WHERE t1.b = t1.b > 0 GROUP BY t2.b;
+DECODE((SELECT ENCODE('secret', 'ABC') FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b), t2.a)
+secret
+SELECT DECODE((SELECT ENCODE('secret', t1.a) FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b), 'ABC')
+FROM t1,t2 WHERE t1.b = t1.b > 0 GROUP BY t2.b;
+DECODE((SELECT ENCODE('secret', t1.a) FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b), 'ABC')
+secret
+TRUNCATE TABLE t1;
+TRUNCATE TABLE t2;
+INSERT INTO t1 VALUES ('EDF', 3), ('BCD', 2), ('ABC', 1);
+INSERT INTO t2 VALUES ('EDF', 3), ('BCD', 2), ('ABC', 1);
+SELECT DECODE((SELECT ENCODE('secret', t1.a) FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b LIMIT 1), t2.a)
+FROM t2 WHERE t2.b = 1 GROUP BY t2.b;
+DECODE((SELECT ENCODE('secret', t1.a) FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b LIMIT 1), t2.a)
+secret
+DROP TABLE t1, t2;
diff --git a/mysql-test/r/ps.result b/mysql-test/r/ps.result
index f64d58ff8f4..c26a324d00b 100644
--- a/mysql-test/r/ps.result
+++ b/mysql-test/r/ps.result
@@ -2947,4 +2947,23 @@ execute stmt;
 Db	Name	Definer	Time zone	Type	Execute at	Interval value	Interval field	Starts	Ends	Status	Originator	character_set_client	collation_connection	Database Collation
 drop table t1;
 deallocate prepare stmt;
+#
+# Bug#49141: Encode function is significantly slower in 5.1 compared to 5.0
+#
+prepare encode from "select encode(?, ?) into @ciphertext";
+prepare decode from "select decode(?, ?) into @plaintext";
+set @str="abc", @key="cba";
+execute encode using @str, @key;
+execute decode using @ciphertext, @key;
+select @plaintext;
+@plaintext
+abc
+set @str="bcd", @key="dcb";
+execute encode using @str, @key;
+execute decode using @ciphertext, @key;
+select @plaintext;
+@plaintext
+bcd
+deallocate prepare encode;
+deallocate prepare decode;
 End of 5.1 tests.
diff --git a/mysql-test/t/func_str.test b/mysql-test/t/func_str.test
index 66b9eabd385..8942b0a2faf 100644
--- a/mysql-test/t/func_str.test
+++ b/mysql-test/t/func_str.test
@@ -1318,3 +1318,37 @@ insert into t1 values (-1),(null);
 explain select 1 as a from t1,(select decode(f1,f1) as b from t1) a;
 explain select 1 as a from t1,(select encode(f1,f1) as b from t1) a;
 drop table t1;
+
+--echo #
+--echo # Bug#49141: Encode function is significantly slower in 5.1 compared to 5.0
+--echo #
+
+--disable_warnings
+DROP TABLE IF EXISTS t1, t2;
+--enable_warnings
+
+CREATE TABLE t1 (a VARCHAR(20), b INT);
+CREATE TABLE t2 (a VARCHAR(20), b INT);
+
+INSERT INTO t1 VALUES ('ABC', 1);
+INSERT INTO t2 VALUES ('ABC', 1);
+
+SELECT DECODE((SELECT ENCODE('secret', t1.a) FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b), t2.a)
+  FROM t1,t2 WHERE t1.b = t1.b > 0 GROUP BY t2.b;
+
+SELECT DECODE((SELECT ENCODE('secret', 'ABC') FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b), t2.a)
+  FROM t1,t2 WHERE t1.b = t1.b > 0 GROUP BY t2.b;
+
+SELECT DECODE((SELECT ENCODE('secret', t1.a) FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b), 'ABC')
+  FROM t1,t2 WHERE t1.b = t1.b > 0 GROUP BY t2.b;
+
+TRUNCATE TABLE t1;
+TRUNCATE TABLE t2;
+
+INSERT INTO t1 VALUES ('EDF', 3), ('BCD', 2), ('ABC', 1);
+INSERT INTO t2 VALUES ('EDF', 3), ('BCD', 2), ('ABC', 1);
+
+SELECT DECODE((SELECT ENCODE('secret', t1.a) FROM t1,t2 WHERE t1.a = t2.a GROUP BY t1.b LIMIT 1), t2.a)
+  FROM t2 WHERE t2.b = 1 GROUP BY t2.b;
+
+DROP TABLE t1, t2;
diff --git a/mysql-test/t/ps.test b/mysql-test/t/ps.test
index 4870f4836df..b0930a42b41 100644
--- a/mysql-test/t/ps.test
+++ b/mysql-test/t/ps.test
@@ -3032,5 +3032,21 @@ execute stmt;
 drop table t1;
 deallocate prepare stmt;
 
+--echo #
+--echo # Bug#49141: Encode function is significantly slower in 5.1 compared to 5.0
+--echo #
+
+prepare encode from "select encode(?, ?) into @ciphertext";
+prepare decode from "select decode(?, ?) into @plaintext";
+set @str="abc", @key="cba";
+execute encode using @str, @key;
+execute decode using @ciphertext, @key;
+select @plaintext;
+set @str="bcd", @key="dcb";
+execute encode using @str, @key;
+execute decode using @ciphertext, @key;
+select @plaintext;
+deallocate prepare encode;
+deallocate prepare decode;
 
 --echo End of 5.1 tests.
diff --git a/sql/item_strfunc.cc b/sql/item_strfunc.cc
index 183a628f8e4..b6d3f45f4c2 100644
--- a/sql/item_strfunc.cc
+++ b/sql/item_strfunc.cc
@@ -1720,68 +1720,65 @@ String *Item_func_encrypt::val_str(String *str)
 #endif	/* HAVE_CRYPT */
 }
 
+bool Item_func_encode::seed()
+{
+  char buf[80];
+  ulong rand_nr[2];
+  String *key, tmp(buf, sizeof(buf), system_charset_info);
+
+  if (!(key= args[1]->val_str(&tmp)))
+    return TRUE;
+
+  hash_password(rand_nr, key->ptr(), key->length());
+  sql_crypt.init(rand_nr);
+
+  return FALSE;
+}
+
 void Item_func_encode::fix_length_and_dec()
 {
   max_length=args[0]->max_length;
   maybe_null=args[0]->maybe_null || args[1]->maybe_null;
   collation.set(&my_charset_bin);
+  /* Precompute the seed state if the item is constant. */
+  seeded= args[1]->const_item() &&
+          (args[1]->result_type() == STRING_RESULT) && !seed();
 }
 
 String *Item_func_encode::val_str(String *str)
 {
   String *res;
-  char pw_buff[80];
-  String tmp_pw_value(pw_buff, sizeof(pw_buff), system_charset_info);
-  String *password;
   DBUG_ASSERT(fixed == 1);
 
   if (!(res=args[0]->val_str(str)))
   {
-    null_value=1; /* purecov: inspected */
-    return 0; /* purecov: inspected */
+    null_value= 1;
+    return NULL;
   }
 
-  if (!(password=args[1]->val_str(& tmp_pw_value)))
+  if (!seeded && seed())
   {
-    null_value=1;
-    return 0;
+    null_value= 1;
+    return NULL;
   }
 
-  null_value=0;
-  res=copy_if_not_alloced(str,res,res->length());
-  SQL_CRYPT sql_crypt(password->ptr(), password->length());
-  sql_crypt.init();
-  sql_crypt.encode((char*) res->ptr(),res->length());
-  res->set_charset(&my_charset_bin);
+  null_value= 0;
+  res= copy_if_not_alloced(str, res, res->length());
+  transform(res);
+  sql_crypt.reinit();
+
   return res;
 }
 
-String *Item_func_decode::val_str(String *str)
+void Item_func_encode::transform(String *res)
 {
-  String *res;
-  char pw_buff[80];
-  String tmp_pw_value(pw_buff, sizeof(pw_buff), system_charset_info);
-  String *password;
-  DBUG_ASSERT(fixed == 1);
-
-  if (!(res=args[0]->val_str(str)))
-  {
-    null_value=1; /* purecov: inspected */
-    return 0; /* purecov: inspected */
-  }
-
-  if (!(password=args[1]->val_str(& tmp_pw_value)))
-  {
-    null_value=1;
-    return 0;
-  }
+  sql_crypt.encode((char*) res->ptr(),res->length());
+  res->set_charset(&my_charset_bin);
+}
 
-  null_value=0;
-  res=copy_if_not_alloced(str,res,res->length());
-  SQL_CRYPT sql_crypt(password->ptr(), password->length());
-  sql_crypt.init();
+void Item_func_decode::transform(String *res)
+{
   sql_crypt.decode((char*) res->ptr(),res->length());
-  return res;
 }
 
 
diff --git a/sql/item_strfunc.h b/sql/item_strfunc.h
index 2cdb45100ae..59241872e63 100644
--- a/sql/item_strfunc.h
+++ b/sql/item_strfunc.h
@@ -351,12 +351,22 @@ public:
 
 class Item_func_encode :public Item_str_func
 {
+private:
+  /** Whether the PRNG has already been seeded. */
+  bool seeded;
+protected:
+  SQL_CRYPT sql_crypt;
 public:
   Item_func_encode(Item *a, Item *seed):
     Item_str_func(a, seed) {}
   String *val_str(String *);
   void fix_length_and_dec();
   const char *func_name() const { return "encode"; }
+protected:
+  virtual void transform(String *);
+private:
+  /** Provide a seed for the PRNG sequence. */
+  bool seed();
 };
 
 
@@ -364,8 +374,9 @@ class Item_func_decode :public Item_func_encode
 {
 public:
   Item_func_decode(Item *a, Item *seed): Item_func_encode(a, seed) {}
-  String *val_str(String *);
   const char *func_name() const { return "decode"; }
+protected:
+  void transform(String *);
 };
 
 
diff --git a/sql/sql_crypt.cc b/sql/sql_crypt.cc
index c4f93cc2a33..3d7d248782b 100644
--- a/sql/sql_crypt.cc
+++ b/sql/sql_crypt.cc
@@ -28,14 +28,7 @@
 
 #include "mysql_priv.h"
 
-SQL_CRYPT::SQL_CRYPT(const char *password, uint length)
-{
-  ulong rand_nr[2];
-  hash_password(rand_nr,password, length);
-  crypt_init(rand_nr);
-}
-
-void SQL_CRYPT::crypt_init(ulong *rand_nr)
+void SQL_CRYPT::init(ulong *rand_nr)
 {
   uint i;
   randominit(&rand,rand_nr[0],rand_nr[1]);
diff --git a/sql/sql_crypt.h b/sql/sql_crypt.h
index a5a6bee8a58..2b56c387bd1 100644
--- a/sql/sql_crypt.h
+++ b/sql/sql_crypt.h
@@ -23,15 +23,15 @@ class SQL_CRYPT :public Sql_alloc
   struct rand_struct rand,org_rand;
   char decode_buff[256],encode_buff[256];
   uint shift;
-  void crypt_init(ulong *seed);
  public:
-  SQL_CRYPT(const char *seed, uint length);
+  SQL_CRYPT() {}
   SQL_CRYPT(ulong *seed)
   {
-    crypt_init(seed);
+    init(seed);
   }
   ~SQL_CRYPT() {}
-  void init() { shift=0; rand=org_rand; }
+  void init(ulong *seed);
+  void reinit() { shift=0; rand=org_rand; }
   void encode(char *str, uint length);
   void decode(char *str, uint length);
 };