[packages/percona-server.git] / query_cache_enhance.patch

# name       : query_cache_with_comments.patch
# introduced : 11 or before
# maintainer : Oleg
#
#!!! notice !!!
# Any small change to this file in the main branch
# should be done or reviewed by the maintainer!
--- /dev/null
+++ b/patch_info/query_cache_enhance.patch
@@ -0,0 +1,15 @@
+File=query_cache_enhance.patch
+Name= query cache Percona's cumulative patch
+Version=1.0
+Author=Percona <info@percona.com>
+License=GPL
+Comment= 1) Add new status - Waiting on query cache mutex (status_wait_query_cache_mutex.patch)
+         2) Remove comments from query (need for cache hit) (query_cache_with_comments.patch)
+         3) Totally disable query cache (query_cache_totally_disable.info)
+2010-05 - First version avaliable (query_cache_with_comments.patch)
+2010-07 - First version avaliable (status_wait_query_cache_mutex.patch
+2010-07 - First version avaliable (query_cache_totally_disable.info)
+2010-07 - Fix crash (query_cache_with_comments.patch)
+2010-07 - Fix incorrect behavior diff (query_cache_with_comments.patch)
+2010-09 - Merge patches to one
+2010-11 - Ported to 5.5
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -904,6 +904,7 @@
 #endif
 #ifdef HAVE_QUERY_CACHE
 ulong query_cache_min_res_unit= QUERY_CACHE_MIN_RESULT_DATA_SIZE;
+my_bool opt_query_cache_strip_comments= FALSE;
 Query_cache query_cache;
 #endif
 #ifdef HAVE_SMEM
--- a/sql/mysqld.h
+++ b/sql/mysqld.h
@@ -91,6 +91,7 @@
 extern my_bool opt_log, opt_slow_log;
 extern my_bool opt_backup_history_log;
 extern my_bool opt_backup_progress_log;
+extern my_bool opt_query_cache_strip_comments;
 extern ulonglong log_output_options;
 extern ulong log_backup_output_options;
 extern my_bool opt_log_queries_not_using_indexes;
--- /dev/null
+++ b/sql/query_strip_comments.h
@@ -0,0 +1,37 @@
+#ifndef _SQL_QUERY_STRIPC_COMMENTS_H_
+#define _SQL_QUERY_STRIPC_COMMENTS_H_
+#ifdef HAVE_QUERY_CACHE
+
+// implemented in sql_cache.cc
+class QueryStripComments
+{
+private:
+  QueryStripComments(const QueryStripComments&);
+  QueryStripComments& operator=(const QueryStripComments&);
+public:
+  QueryStripComments();
+  ~QueryStripComments();
+  void set(const char* a_query, uint a_query_length, uint a_additional_length);
+  
+  char* query()        { return buffer; }
+  uint  query_length() { return length; }
+private:
+  void cleanup();
+private:
+  char* buffer;
+  uint  length /*query length, not buffer length*/;
+  uint  buffer_length;
+};
+class QueryStripComments_Backup
+{
+public:
+  QueryStripComments_Backup(THD* a_thd,QueryStripComments* qsc);
+  ~QueryStripComments_Backup();
+private:
+  THD*  thd;
+  char* query;
+  uint  length;
+};
+
+#endif // HAVE_QUERY_CACHE
+#endif // _SQL_QUERY_STRIPC_COMMENTS_H_
--- a/sql/sql_cache.cc
+++ b/sql/sql_cache.cc
@@ -344,6 +344,181 @@
 #include "probes_mysql.h"
 #include "transaction.h"
 
+#include "query_strip_comments.h"
+
+QueryStripComments::QueryStripComments()
+{
+  buffer = 0;
+  length = 0;
+  buffer_length = 0;
+}
+QueryStripComments::~QueryStripComments()
+{
+  cleanup();
+}
+
+inline bool query_strip_comments_is_white_space(char c)
+{
+  return ((' ' == c) || ('\t' == c) || ('\r' == c) || ('\n' ==c ));
+}
+void QueryStripComments::set(const char* query, uint query_length, uint additional_length)
+{
+  uint new_buffer_length = query_length + additional_length;
+  if(new_buffer_length > buffer_length)
+  {
+    cleanup();
+    buffer = (char*)my_malloc(new_buffer_length,MYF(0));
+  }
+  uint query_position = 0;
+  uint position = 0;
+  // Skip whitespaces from begin
+  while((query_position < query_length) && query_strip_comments_is_white_space(query[query_position]))
+  {
+    ++query_position;
+  }
+  long int last_space = -1;
+  while(query_position < query_length)
+  {
+    char current = query[query_position];
+    bool insert_space = false; // insert space to buffer, (IMPORTANT) don't update query_position
+    switch(current)
+    {
+    case '\'':
+    case '"':
+      {
+        buffer[position++] = query[query_position++]; // copy current symbol
+        while(query_position < query_length)
+        {
+          if(current == query[query_position]) // found pair quote
+          {
+            break;
+          }
+          buffer[position++] = query[query_position++]; // copy current symbol
+        }
+        break;
+      }
+    case '/':
+      {
+        if(((query_position + 2) < query_length) && ('*' == query[query_position+1]) && ('!' != query[query_position+2]))
+        {
+          query_position += 2; // skip "/*"
+          do
+          {
+            if('*' == query[query_position] && '/' == query[query_position+1]) // check for "*/"
+            {
+              query_position += 2; // skip "*/"
+              insert_space = true;
+              break;
+            }
+            else
+            {
+              ++query_position;
+            }
+          }
+          while(query_position < query_length);
+          if(!insert_space)
+          {
+            continue;
+          }
+        }
+        break;
+      }
+    case '-':
+      {
+        if(query[query_position+1] == '-')
+        {
+          ++query_position; // skip "-", and go to search of "\n"
+        }
+        else
+        {
+          break;
+        }
+      }
+    case '#':
+      {
+        do
+        {
+          ++query_position; // skip current symbol (# or -)
+          if('\n' == query[query_position])  // check for '\n'
+          {
+            ++query_position; // skip '\n'
+            insert_space = true;
+            break;
+          }
+        }
+        while(query_position < query_length);
+        if(insert_space)
+        {
+          break;
+        }
+        else
+        {
+          continue;
+        }
+      }
+    default:
+      if(query_strip_comments_is_white_space(current))
+      {
+        insert_space = true;
+        ++query_position;
+      }
+      break; // make gcc happy
+    }
+    if(insert_space)
+    {
+      if((last_space + 1) != position)
+      {
+        last_space = position;
+        buffer[position++] = ' ';
+      }
+    }
+    else
+    {
+      buffer[position++] = query[query_position++];
+    }
+  }
+  while((0 < position) && query_strip_comments_is_white_space(buffer[position - 1]))
+  {
+    --position;
+  }
+  buffer[position] = 0;
+  length = position;
+}
+void QueryStripComments::cleanup()
+{
+  if(buffer)
+  {
+    my_free(buffer);
+  }
+  buffer        = 0;
+  length        = 0;
+  buffer_length = 0;
+}
+QueryStripComments_Backup::QueryStripComments_Backup(THD* a_thd,QueryStripComments* qsc)
+{
+  if(opt_query_cache_strip_comments)
+  {
+    thd = a_thd;
+    query = thd->query();
+    length = thd->query_length();
+    qsc->set(query,length,thd->db_length + 1 + QUERY_CACHE_FLAGS_SIZE);
+    thd->set_query(qsc->query(),qsc->query_length());
+  }
+  else
+  {
+    thd = 0;
+    query = 0;
+    length = 0;
+  }
+}
+QueryStripComments_Backup::~QueryStripComments_Backup()
+{
+  if(thd)
+  {
+    thd->set_query(query,length);
+  }
+}
+
 #ifdef EMBEDDED_LIBRARY
 #include "emb_qcache.h"
 #endif
@@ -454,7 +629,12 @@
   Query_cache_wait_state wait_state(thd, __func__, __FILE__, __LINE__);
   DBUG_ENTER("Query_cache::try_lock");
 
+  const char* old_proc_info= thd->proc_info;
+  thd_proc_info(thd,"Waiting on query cache mutex");
+  DEBUG_SYNC(thd, "before_query_cache_mutex");
   mysql_mutex_lock(&structure_guard_mutex);
+  DEBUG_SYNC(thd, "after_query_cache_mutex");
+  thd->proc_info = old_proc_info;
   while (1)
   {
     if (m_cache_lock_status == Query_cache::UNLOCKED)
@@ -1274,6 +1454,8 @@
       unlock();
       DBUG_VOID_RETURN;
     }
+    QueryStripComments *query_strip_comments = &(thd->query_strip_comments);
+    QueryStripComments_Backup backup(thd,query_strip_comments);
 
     /* Key is query + database + flag */
     if (thd->db_length)
@@ -1451,6 +1633,9 @@
   Query_cache_block_table *block_table, *block_table_end;
   ulong tot_length;
   Query_cache_query_flags flags;
+  QueryStripComments *query_strip_comments = &(thd->query_strip_comments);
+  char *sql_backup          = sql;
+  uint  query_length_backup = query_length;
   DBUG_ENTER("Query_cache::send_result_to_client");
 
   /*
@@ -1472,21 +1657,103 @@
 
   {
     uint i= 0;
-    /*
-      Skip '(' characters in queries like following:
-      (select a from t1) union (select a from t1);
-    */
-    while (sql[i]=='(')
-      i++;
+    if(opt_query_cache_strip_comments)
+    {
+      /* Skip all comments and non-letter symbols */
+      uint& query_position = i;
+      char* query = sql;
+      while(query_position < query_length)
+      {
+        bool check = false;
+        char current = query[query_position];
+        switch(current)
+        {
+        case '/':
+          if(((query_position + 2) < query_length) && ('*' == query[query_position+1]) && ('!' != query[query_position+2]))
+          {
+            query_position += 2; // skip "/*"
+            do
+            {
+              if('*' == query[query_position] && '/' == query[query_position+1]) // check for "*/" (without space)
+              {
+                query_position += 2; // skip "*/" (without space)
+                break;
+              }
+              else
+              {
+                ++query_position;
+              }
+            }
+            while(query_position < query_length);
+            continue; // analyze current symbol
+          }
+          break;
+        case '-':
+          if(query[query_position+1] == '-')
+          {
+            ++query_position; // skip "-"
+          }
+          else
+          {
+            break;
+          }
+        case '#':
+          do
+          {
+            ++query_position; // skip current symbol
+            if('\n' == query[query_position])  // check for '\n'
+            {
+              ++query_position; // skip '\n'
+              break;
+            }
+          }
+          while(query_position < query_length);
+          continue; // analyze current symbol
+        case '\r':
+        case '\n':
+        case '\t':
+        case ' ':
+        case '(':
+        case ')':
+          break;
+        default:
+          check = true;
+          break; // make gcc happy
+        } // switch(current)
+        if(check)
+        {
+          if(query_position + 2 < query_length)
+          {
+            // cacheable
+            break;
+          }
+          else
+          {
+            DBUG_PRINT("qcache", ("The statement is not a SELECT; Not cached"));
+            goto err;
+          }
+        } // if(check)
+        ++query_position;
+      } // while(query_position < query_length)
+    }
+    else // if(opt_query_cache_strip_comments)
+    {
+      /*
+        Skip '(' characters in queries like following:
+        (select a from t1) union (select a from t1);
+      */
+      while (sql[i]=='(')
+        i++;
 
-    /*
-      Test if the query is a SELECT
-      (pre-space is removed in dispatch_command).
+    } // if(opt_query_cache_strip_comments)    
+      /*
+        Test if the query is a SELECT
+        (pre-space is removed in dispatch_command).
 
-      First '/' looks like comment before command it is not
-      frequently appeared in real life, consequently we can
-      check all such queries, too.
-    */
+        First '/' looks like comment before command it is not
+        frequently appeared in real life, consequently we can
+        check all such queries, too.
+      */
     if ((my_toupper(system_charset_info, sql[i])     != 'S' ||
          my_toupper(system_charset_info, sql[i + 1]) != 'E' ||
          my_toupper(system_charset_info, sql[i + 2]) != 'L') &&
@@ -1521,6 +1788,12 @@
     goto err_unlock;
 
   Query_cache_block *query_block;
+  if(opt_query_cache_strip_comments)
+  {
+    query_strip_comments->set(sql, query_length, thd->db_length + 1 + QUERY_CACHE_FLAGS_SIZE);
+    sql          = query_strip_comments->query();
+    query_length = query_strip_comments->query_length();
+  }
 
   tot_length= query_length + thd->db_length + 1 + QUERY_CACHE_FLAGS_SIZE;
   if (thd->db_length)
@@ -1587,6 +1860,8 @@
 	 (uchar*) &flags, QUERY_CACHE_FLAGS_SIZE);
   query_block = (Query_cache_block *)  my_hash_search(&queries, (uchar*) sql,
                                                       tot_length);
+  sql          = sql_backup;
+  query_length = query_length_backup;
   /* Quick abort on unlocked data */
   if (query_block == 0 ||
       query_block->query()->result() == 0 ||
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -40,6 +40,9 @@
 #include "thr_lock.h"             /* thr_lock_type, THR_LOCK_DATA,
                                      THR_LOCK_INFO */
 
+#ifdef HAVE_QUERY_CACHE
+#include "query_strip_comments.h"
+#endif // HAVE_QUERY_CACHE
 
 class Reprepare_observer;
 class Relay_log_info;
@@ -764,6 +767,9 @@
     statement lifetime. FIXME: must be const
   */
    ulong id;
+#ifdef HAVE_QUERY_CACHE
+  QueryStripComments query_strip_comments; // see sql_cache.cc
+#endif //HAVE_QUERY_CACHE
 
   /*
     MARK_COLUMNS_NONE:  Means mark_used_colums is not set and no indicator to
--- a/sql/sys_vars.cc
+++ b/sql/sys_vars.cc
@@ -1809,6 +1809,11 @@
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0),
        ON_UPDATE(fix_query_cache_size));
 
+static Sys_var_mybool Sys_query_cache_strip_comments(
+       "query_cache_strip_comments", "Enable and disable optimisation \"strip comment for query cache\" - optimisation strip all comments from query while search query result in query cache",
+       GLOBAL_VAR(opt_query_cache_strip_comments), CMD_LINE(OPT_ARG),
+       DEFAULT(FALSE));
+
 static Sys_var_ulong Sys_query_cache_limit(
        "query_cache_limit",
        "Don't cache results that are bigger than this",
--- /dev/null
+++ b/mysql-test/include/percona_query_cache_with_comments.inc
@@ -0,0 +1,95 @@
+--source include/percona_query_cache_with_comments_clear.inc
+let $query=/* with comment first */select * from t1;
+eval $query;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=# with comment first
+select * from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=-- with comment first
+select * from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=/* with comment first and "quote" */select * from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=# with comment first and "quote"
+select * from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=-- with comment first and "quote" 
+select * from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=
+    /* with comment and whitespaces first */select * from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query= 
+    # with comment and whitespaces first
+select * from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=
+    -- with comment and whitespaces first
+select * from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $internal=* internal comment *;
+
+let $query=select * /$internal/ from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+let $query=select */$internal/ from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+let $query=select */$internal/from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $internal=* internal comment with "quote" *;
+
+let $query=select * /$internal/ from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+let $query=select */$internal/ from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+let $query=select */$internal/from t1;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select * from t1
+;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select * from t1 ;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select * from t1	;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select * from t1
+/* comment in the end */;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select * from t1
+/* *\/ */;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select * from t1
+/* comment in the end */
+;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select * from t1 #comment in the end;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select * from t1 #comment in the end
+;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select * from t1 -- comment in the end;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select * from t1 -- comment in the end
+;
+--source include/percona_query_cache_with_comments_eval.inc
+
+let $query=select ' \'  ' from t1;
+--source include/percona_query_cache_with_comments_eval.inc
--- /dev/null
+++ b/mysql-test/include/percona_query_cache_with_comments_begin.inc
@@ -0,0 +1,12 @@
+-- source include/have_query_cache.inc
+
+set GLOBAL query_cache_size=1355776;
+
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+
+create table t1 (a int not null);
+insert into t1 values (1),(2),(3);
+
+--source include/percona_query_cache_with_comments_clear.inc
--- /dev/null
+++ b/mysql-test/include/percona_query_cache_with_comments_clear.inc
@@ -0,0 +1,5 @@
+# Reset query cache variables.
+flush query cache; # This crashed in some versions
+flush query cache; # This crashed in some versions
+reset query cache;
+flush status;
--- /dev/null
+++ b/mysql-test/include/percona_query_cache_with_comments_end.inc
@@ -0,0 +1,3 @@
+DROP TABLE t1;
+SET GLOBAL query_cache_size=default;
+set global query_cache_strip_comments=OFF;
--- /dev/null
+++ b/mysql-test/include/percona_query_cache_with_comments_eval.inc
@@ -0,0 +1,7 @@
+echo -----------------------------------------------------;
+echo $query;
+echo -----------------------------------------------------;
+--source include/percona_query_cache_with_comments_show.inc
+eval $query;
+eval $query;
+--source include/percona_query_cache_with_comments_show.inc
--- /dev/null
+++ b/mysql-test/include/percona_query_cache_with_comments_show.inc
@@ -0,0 +1,8 @@
+let $show=show status like "Qcache_queries_in_cache";
+eval $show;
+let $show=show status like "Qcache_inserts";
+eval $show;
+let $show=show status like "Qcache_hits";
+eval $show;
+
+
--- /dev/null
+++ b/mysql-test/r/percona_query_cache_with_comments.result
@@ -0,0 +1,866 @@
+set global query_cache_strip_comments=ON;
+set GLOBAL query_cache_size=1355776;
+drop table if exists t1;
+create table t1 (a int not null);
+insert into t1 values (1),(2),(3);
+flush query cache;
+flush query cache;
+reset query cache;
+flush status;
+flush query cache;
+flush query cache;
+reset query cache;
+flush status;
+/* with comment first */select * from t1;
+a
+1
+2
+3
+-----------------------------------------------------
+/* with comment first */select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	0
+/* with comment first */select * from t1;
+a
+1
+2
+3
+/* with comment first */select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	2
+-----------------------------------------------------
+# with comment first
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	2
+# with comment first
+select * from t1;
+a
+1
+2
+3
+# with comment first
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	4
+-----------------------------------------------------
+-- with comment first
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	4
+-- with comment first
+select * from t1;
+a
+1
+2
+3
+-- with comment first
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	6
+-----------------------------------------------------
+/* with comment first and "quote" */select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	6
+/* with comment first and "quote" */select * from t1;
+a
+1
+2
+3
+/* with comment first and "quote" */select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	8
+-----------------------------------------------------
+# with comment first and "quote"
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	8
+# with comment first and "quote"
+select * from t1;
+a
+1
+2
+3
+# with comment first and "quote"
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	10
+-----------------------------------------------------
+-- with comment first and "quote" 
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	10
+-- with comment first and "quote" 
+select * from t1;
+a
+1
+2
+3
+-- with comment first and "quote" 
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	12
+-----------------------------------------------------
+/* with comment and whitespaces first */select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	12
+/* with comment and whitespaces first */select * from t1;
+a
+1
+2
+3
+/* with comment and whitespaces first */select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	14
+-----------------------------------------------------
+# with comment and whitespaces first
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	14
+# with comment and whitespaces first
+select * from t1;
+a
+1
+2
+3
+# with comment and whitespaces first
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	16
+-----------------------------------------------------
+-- with comment and whitespaces first
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	16
+-- with comment and whitespaces first
+select * from t1;
+a
+1
+2
+3
+-- with comment and whitespaces first
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	18
+-----------------------------------------------------
+select * /* internal comment */ from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	18
+select * /* internal comment */ from t1;
+a
+1
+2
+3
+select * /* internal comment */ from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	20
+-----------------------------------------------------
+select */* internal comment */ from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	20
+select */* internal comment */ from t1;
+a
+1
+2
+3
+select */* internal comment */ from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	22
+-----------------------------------------------------
+select */* internal comment */from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	22
+select */* internal comment */from t1;
+a
+1
+2
+3
+select */* internal comment */from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	24
+-----------------------------------------------------
+select * /* internal comment with "quote" */ from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	24
+select * /* internal comment with "quote" */ from t1;
+a
+1
+2
+3
+select * /* internal comment with "quote" */ from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	26
+-----------------------------------------------------
+select */* internal comment with "quote" */ from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	26
+select */* internal comment with "quote" */ from t1;
+a
+1
+2
+3
+select */* internal comment with "quote" */ from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	28
+-----------------------------------------------------
+select */* internal comment with "quote" */from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	28
+select */* internal comment with "quote" */from t1;
+a
+1
+2
+3
+select */* internal comment with "quote" */from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	30
+-----------------------------------------------------
+select * from t1
+
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	30
+select * from t1
+;
+a
+1
+2
+3
+select * from t1
+;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	32
+-----------------------------------------------------
+select * from t1 
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	32
+select * from t1 ;
+a
+1
+2
+3
+select * from t1 ;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	34
+-----------------------------------------------------
+select * from t1	
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	34
+select * from t1	;
+a
+1
+2
+3
+select * from t1	;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	36
+-----------------------------------------------------
+select * from t1
+/* comment in the end */
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	36
+select * from t1
+/* comment in the end */;
+a
+1
+2
+3
+select * from t1
+/* comment in the end */;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	38
+-----------------------------------------------------
+select * from t1
+/* *\/ */
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	38
+select * from t1
+/* *\/ */;
+a
+1
+2
+3
+select * from t1
+/* *\/ */;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	40
+-----------------------------------------------------
+select * from t1
+/* comment in the end */
+
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	40
+select * from t1
+/* comment in the end */
+;
+a
+1
+2
+3
+select * from t1
+/* comment in the end */
+;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	42
+-----------------------------------------------------
+select * from t1 #comment in the end
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	42
+select * from t1 #comment in the end;
+a
+1
+2
+3
+select * from t1 #comment in the end;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	44
+-----------------------------------------------------
+select * from t1 #comment in the end
+
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	44
+select * from t1 #comment in the end
+;
+a
+1
+2
+3
+select * from t1 #comment in the end
+;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	46
+-----------------------------------------------------
+select * from t1 -- comment in the end
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	46
+select * from t1 -- comment in the end;
+a
+1
+2
+3
+select * from t1 -- comment in the end;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	48
+-----------------------------------------------------
+select * from t1 -- comment in the end
+
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	48
+select * from t1 -- comment in the end
+;
+a
+1
+2
+3
+select * from t1 -- comment in the end
+;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	50
+-----------------------------------------------------
+select ' \'  ' from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	50
+select ' \'  ' from t1;
+'  
+ '  
+ '  
+ '  
+select ' \'  ' from t1;
+'  
+ '  
+ '  
+ '  
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	2
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	2
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	51
+DROP TABLE t1;
+SET GLOBAL query_cache_size=default;
+set global query_cache_strip_comments=OFF;
--- /dev/null
+++ b/mysql-test/r/percona_query_cache_with_comments_crash.result
@@ -0,0 +1,21 @@
+set GLOBAL query_cache_size=1355776;
+drop table if exists t1;
+create table t1 (a int not null);
+insert into t1 values (1),(2),(3);
+flush query cache;
+flush query cache;
+reset query cache;
+flush status;
+( select * from t1 );
+a
+1
+2
+3
+/*!40101 SET @OLD_SQL_MODE := @@SQL_MODE, @@SQL_MODE := REPLACE(REPLACE(@@SQL_MODE, 'ANSI_QUOTES', ''), ',,', ','), @OLD_QUOTE := @@SQL_QUOTE_SHOW_CREATE, @@SQL_QUOTE_SHOW_CREATE := 1 */;
+/* only comment */;
+# only comment
+;
+-- only comment
+;
+DROP TABLE t1;
+SET GLOBAL query_cache_size= default;
--- /dev/null
+++ b/mysql-test/r/percona_query_cache_with_comments_disable.result
@@ -0,0 +1,865 @@
+set GLOBAL query_cache_size=1355776;
+drop table if exists t1;
+create table t1 (a int not null);
+insert into t1 values (1),(2),(3);
+flush query cache;
+flush query cache;
+reset query cache;
+flush status;
+flush query cache;
+flush query cache;
+reset query cache;
+flush status;
+/* with comment first */select * from t1;
+a
+1
+2
+3
+-----------------------------------------------------
+/* with comment first */select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	0
+/* with comment first */select * from t1;
+a
+1
+2
+3
+/* with comment first */select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	2
+-----------------------------------------------------
+# with comment first
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	2
+# with comment first
+select * from t1;
+a
+1
+2
+3
+# with comment first
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	2
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	2
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	2
+-----------------------------------------------------
+-- with comment first
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	2
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	2
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	2
+-- with comment first
+select * from t1;
+a
+1
+2
+3
+-- with comment first
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	3
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	3
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	2
+-----------------------------------------------------
+/* with comment first and "quote" */select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	3
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	3
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	2
+/* with comment first and "quote" */select * from t1;
+a
+1
+2
+3
+/* with comment first and "quote" */select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	4
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	4
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	3
+-----------------------------------------------------
+# with comment first and "quote"
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	4
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	4
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	3
+# with comment first and "quote"
+select * from t1;
+a
+1
+2
+3
+# with comment first and "quote"
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	5
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	5
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	3
+-----------------------------------------------------
+-- with comment first and "quote" 
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	5
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	5
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	3
+-- with comment first and "quote" 
+select * from t1;
+a
+1
+2
+3
+-- with comment first and "quote" 
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	6
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	6
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	3
+-----------------------------------------------------
+/* with comment and whitespaces first */select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	6
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	6
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	3
+/* with comment and whitespaces first */select * from t1;
+a
+1
+2
+3
+/* with comment and whitespaces first */select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	7
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	7
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	4
+-----------------------------------------------------
+# with comment and whitespaces first
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	7
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	7
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	4
+# with comment and whitespaces first
+select * from t1;
+a
+1
+2
+3
+# with comment and whitespaces first
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	8
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	8
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	4
+-----------------------------------------------------
+-- with comment and whitespaces first
+select * from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	8
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	8
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	4
+-- with comment and whitespaces first
+select * from t1;
+a
+1
+2
+3
+-- with comment and whitespaces first
+select * from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	9
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	9
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	4
+-----------------------------------------------------
+select * /* internal comment */ from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	9
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	9
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	4
+select * /* internal comment */ from t1;
+a
+1
+2
+3
+select * /* internal comment */ from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	10
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	10
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	5
+-----------------------------------------------------
+select */* internal comment */ from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	10
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	10
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	5
+select */* internal comment */ from t1;
+a
+1
+2
+3
+select */* internal comment */ from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	11
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	11
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	6
+-----------------------------------------------------
+select */* internal comment */from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	11
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	11
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	6
+select */* internal comment */from t1;
+a
+1
+2
+3
+select */* internal comment */from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	12
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	12
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	7
+-----------------------------------------------------
+select * /* internal comment with "quote" */ from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	12
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	12
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	7
+select * /* internal comment with "quote" */ from t1;
+a
+1
+2
+3
+select * /* internal comment with "quote" */ from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	13
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	13
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	8
+-----------------------------------------------------
+select */* internal comment with "quote" */ from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	13
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	13
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	8
+select */* internal comment with "quote" */ from t1;
+a
+1
+2
+3
+select */* internal comment with "quote" */ from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	14
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	14
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	9
+-----------------------------------------------------
+select */* internal comment with "quote" */from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	14
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	14
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	9
+select */* internal comment with "quote" */from t1;
+a
+1
+2
+3
+select */* internal comment with "quote" */from t1;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	15
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	15
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	10
+-----------------------------------------------------
+select * from t1
+
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	15
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	15
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	10
+select * from t1
+;
+a
+1
+2
+3
+select * from t1
+;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	16
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	16
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	11
+-----------------------------------------------------
+select * from t1 
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	16
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	16
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	11
+select * from t1 ;
+a
+1
+2
+3
+select * from t1 ;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	16
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	16
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	13
+-----------------------------------------------------
+select * from t1	
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	16
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	16
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	13
+select * from t1	;
+a
+1
+2
+3
+select * from t1	;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	16
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	16
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	15
+-----------------------------------------------------
+select * from t1
+/* comment in the end */
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	16
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	16
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	15
+select * from t1
+/* comment in the end */;
+a
+1
+2
+3
+select * from t1
+/* comment in the end */;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	17
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	17
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	16
+-----------------------------------------------------
+select * from t1
+/* *\/ */
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	17
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	17
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	16
+select * from t1
+/* *\/ */;
+a
+1
+2
+3
+select * from t1
+/* *\/ */;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	18
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	18
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	17
+-----------------------------------------------------
+select * from t1
+/* comment in the end */
+
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	18
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	18
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	17
+select * from t1
+/* comment in the end */
+;
+a
+1
+2
+3
+select * from t1
+/* comment in the end */
+;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	18
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	18
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	19
+-----------------------------------------------------
+select * from t1 #comment in the end
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	18
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	18
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	19
+select * from t1 #comment in the end;
+a
+1
+2
+3
+select * from t1 #comment in the end;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	19
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	19
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	20
+-----------------------------------------------------
+select * from t1 #comment in the end
+
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	19
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	19
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	20
+select * from t1 #comment in the end
+;
+a
+1
+2
+3
+select * from t1 #comment in the end
+;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	19
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	19
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	22
+-----------------------------------------------------
+select * from t1 -- comment in the end
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	19
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	19
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	22
+select * from t1 -- comment in the end;
+a
+1
+2
+3
+select * from t1 -- comment in the end;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	20
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	20
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	23
+-----------------------------------------------------
+select * from t1 -- comment in the end
+
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	20
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	20
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	23
+select * from t1 -- comment in the end
+;
+a
+1
+2
+3
+select * from t1 -- comment in the end
+;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	20
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	20
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	25
+-----------------------------------------------------
+select ' \'  ' from t1
+-----------------------------------------------------
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	20
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	20
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	25
+select ' \'  ' from t1;
+'  
+ '  
+ '  
+ '  
+select ' \'  ' from t1;
+'  
+ '  
+ '  
+ '  
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	21
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	21
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	26
+DROP TABLE t1;
+SET GLOBAL query_cache_size=default;
+set global query_cache_strip_comments=OFF;
--- /dev/null
+++ b/mysql-test/r/percona_query_cache_with_comments_prepared_statements.result
@@ -0,0 +1,396 @@
+set GLOBAL query_cache_size=1355776;
+flush query cache;
+flush query cache;
+reset query cache;
+flush status;
+drop table if exists t1;
+create table t1 (a int not null);
+insert into t1 values (1),(2),(3);
+set global query_cache_strip_comments=ON;
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	0
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	0
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	0
+prepare stmt from '/* with comment */ select * from t1';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	0
+execute stmt;
+a
+1
+2
+3
+execute stmt;
+a
+1
+2
+3
+execute stmt;
+a
+1
+2
+3
+execute stmt;
+a
+1
+2
+3
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	5
+prepare stmt from 'select * from t1';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	6
+prepare stmt from 'select * /*internal comment*/from t1';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	7
+prepare stmt from 'select * /*internal comment*/ from t1';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	8
+prepare stmt from 'select * from t1 /* at the end */';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	9
+prepare stmt from 'select * from t1 /* with "quote" */';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	10
+prepare stmt from 'select * from t1 /* with \'quote\' */';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	11
+prepare stmt from 'select * from t1 # 123
+';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	12
+prepare stmt from 'select * from t1 # 123 with "quote"
+';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	13
+prepare stmt from 'select * from t1 # 123 with \'quote\'
+';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	14
+prepare stmt from 'select * from t1
+# 123
+';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	15
+prepare stmt from '#456
+select * from t1
+# 123
+';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	16
+prepare stmt from 'select * from t1 -- 123
+';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	17
+prepare stmt from 'select * from t1
+-- 123
+';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	18
+prepare stmt from '-- comment in first
+select * from t1
+# 123
+';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	1
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	1
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	19
+prepare stmt from '(#456(
+select * from t1
+# 123(
+)';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	2
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	2
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	19
+prepare stmt from '/*test*/(-- comment in first(
+select * from t1
+-- 123 asdasd
+/* test */)';
+execute stmt;
+a
+1
+2
+3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	2
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	2
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	20
+prepare stmt from 'select "test",a from t1';
+execute stmt;
+test	a
+test	1
+test	2
+test	3
+execute stmt;
+test	a
+test	1
+test	2
+test	3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	3
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	3
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	21
+prepare stmt from 'select "test /* internal \'comment\' */",a from t1';
+execute stmt;
+test /* internal 'comment' */	a
+test /* internal 'comment' */	1
+test /* internal 'comment' */	2
+test /* internal 'comment' */	3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	4
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	4
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	21
+prepare stmt from 'select "test #internal comment" ,a from t1';
+execute stmt;
+test #internal comment	a
+test #internal comment	1
+test #internal comment	2
+test #internal comment	3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	5
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	5
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	21
+prepare stmt from 'select "test #internal comment" #external comment
+,a from t1';
+execute stmt;
+test #internal comment	a
+test #internal comment	1
+test #internal comment	2
+test #internal comment	3
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	5
+show status like "Qcache_inserts";
+Variable_name	Value
+Qcache_inserts	5
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	22
+DROP TABLE t1;
+SET GLOBAL query_cache_size= default;
+set global query_cache_strip_comments=OFF;
--- /dev/null
+++ b/mysql-test/t/percona_query_cache_with_comments.test
@@ -0,0 +1,5 @@
+--disable_ps_protocol
+set global query_cache_strip_comments=ON;
+-- source include/percona_query_cache_with_comments_begin.inc
+-- source include/percona_query_cache_with_comments.inc
+-- source include/percona_query_cache_with_comments_end.inc
--- /dev/null
+++ b/mysql-test/t/percona_query_cache_with_comments_crash.test
@@ -0,0 +1,22 @@
+-- source include/have_query_cache.inc
+set GLOBAL query_cache_size=1355776;
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+create table t1 (a int not null);
+insert into t1 values (1),(2),(3);
+flush query cache; # This crashed in some versions
+flush query cache; # This crashed in some versions
+reset query cache;
+flush status;
+( select * from t1 );
+/*!40101 SET @OLD_SQL_MODE := @@SQL_MODE, @@SQL_MODE := REPLACE(REPLACE(@@SQL_MODE, 'ANSI_QUOTES', ''), ',,', ','), @OLD_QUOTE := @@SQL_QUOTE_SHOW_CREATE, @@SQL_QUOTE_SHOW_CREATE := 1 */;
+/* only comment */;
+let query=# only comment
+;
+eval $query;
+let query=-- only comment
+;
+eval $query;
+DROP TABLE t1;
+SET GLOBAL query_cache_size= default;
--- /dev/null
+++ b/mysql-test/t/percona_query_cache_with_comments_disable.test
@@ -0,0 +1,3 @@
+-- source include/percona_query_cache_with_comments_begin.inc
+-- source include/percona_query_cache_with_comments.inc
+-- source include/percona_query_cache_with_comments_end.inc
--- /dev/null
+++ b/mysql-test/t/percona_query_cache_with_comments_prepared_statements.test
@@ -0,0 +1,208 @@
+-- source include/have_query_cache.inc
+
+set GLOBAL query_cache_size=1355776;
+
+# Reset query cache variables.
+flush query cache; # This crashed in some versions
+flush query cache; # This crashed in some versions
+reset query cache;
+flush status;
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+
+#
+# First simple test
+#
+
+create table t1 (a int not null);
+insert into t1 values (1),(2),(3);
+
+set global query_cache_strip_comments=ON;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from '/* with comment */ select * from t1';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+execute stmt;
+execute stmt;
+execute stmt;
+execute stmt;
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * from t1';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * /*internal comment*/from t1';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * /*internal comment*/ from t1';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * from t1 /* at the end */';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * from t1 /* with "quote" */';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * from t1 /* with \'quote\' */';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * from t1 # 123
+';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * from t1 # 123 with "quote"
+';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * from t1 # 123 with \'quote\'
+';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * from t1
+# 123
+';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from '#456
+select * from t1
+# 123
+';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * from t1 -- 123
+';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select * from t1
+-- 123
+';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from '-- comment in first
+select * from t1
+# 123
+';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from '(#456(
+select * from t1
+# 123(
+)';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from '/*test*/(-- comment in first(
+select * from t1
+-- 123 asdasd
+/* test */)';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select "test",a from t1';
+execute stmt;
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select "test /* internal \'comment\' */",a from t1';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select "test #internal comment" ,a from t1';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+prepare stmt from 'select "test #internal comment" #external comment
+,a from t1';
+execute stmt;
+
+show status like "Qcache_queries_in_cache";
+show status like "Qcache_inserts";
+show status like "Qcache_hits";
+
+DROP TABLE t1;
+SET GLOBAL query_cache_size= default;
+set global query_cache_strip_comments=OFF;
--- /dev/null
+++ b/mysql-test/t/percona_status_wait_query_cache_mutex.test
@@ -0,0 +1,35 @@
+--source include/have_query_cache.inc
+--source include/have_debug.inc
+--source include/have_debug_sync.inc
+SET GLOBAL query_cache_size=1355776;
+--source include/percona_query_cache_with_comments_clear.inc
+--let try_lock_mutex_query=SELECT "try_lock_mutex_query" as action
+
+--connect (mutex_locked_conn, localhost, root,,)
+--connect (try_mutex_lock_conn, localhost, root,,)
+
+--connection mutex_locked_conn
+SET DEBUG_SYNC='after_query_cache_mutex SIGNAL mutex_locked WAIT_FOR unlock_mutex';
+send SELECT "mutex_locked_query" as action;
+
+--connection default
+SET DEBUG_SYNC='now WAIT_FOR mutex_locked';
+
+--connection try_mutex_lock_conn
+SET DEBUG_SYNC='before_query_cache_mutex SIGNAL try_lock_mutex';
+send_eval $try_lock_mutex_query;
+
+--connection default
+SET DEBUG_SYNC='now WAIT_FOR try_lock_mutex';
+eval SELECT SQL_NO_CACHE state FROM INFORMATION_SCHEMA.PROCESSLIST WHERE info='$try_lock_mutex_query';
+SET DEBUG_SYNC='now SIGNAL unlock_mutex';
+
+--connection mutex_locked_conn
+reap;
+--connection try_mutex_lock_conn
+reap;
+
+--connection default
+--disconnect mutex_locked_conn
+--disconnect try_mutex_lock_conn
+SET GLOBAL query_cache_size=0;
--- a/mysql-test/r/mysqld--help-notwin.result
+++ b/mysql-test/r/mysqld--help-notwin.result
@@ -491,6 +491,10 @@
  The minimum size for blocks allocated by the query cache
  --query-cache-size=# 
  The memory allocated to store results from old queries
+ --query-cache-strip-comments 
+ Enable and disable optimisation "strip comment for query
+ cache" - optimisation strip all comments from query while
+ search query result in query cache
  --query-cache-type=name 
  OFF = Don't cache or retrieve results. ON = Cache all
  results except SELECT SQL_NO_CACHE ... queries. DEMAND =
@@ -928,6 +932,7 @@
 query-cache-limit 1048576
 query-cache-min-res-unit 4096
 query-cache-size 0
+query-cache-strip-comments FALSE
 query-cache-type ON
 query-cache-wlock-invalidate FALSE
 query-prealloc-size 8192
--- /dev/null
+++ b/mysql-test/r/percona_status_wait_query_cache_mutex.result
@@ -0,0 +1,20 @@
+SET GLOBAL query_cache_size=1355776;
+flush query cache;
+flush query cache;
+reset query cache;
+flush status;
+SET DEBUG_SYNC='after_query_cache_mutex SIGNAL mutex_locked WAIT_FOR unlock_mutex';
+SELECT "mutex_locked_query" as action;
+SET DEBUG_SYNC='now WAIT_FOR mutex_locked';
+SET DEBUG_SYNC='before_query_cache_mutex SIGNAL try_lock_mutex';
+SELECT "try_lock_mutex_query" as action;
+SET DEBUG_SYNC='now WAIT_FOR try_lock_mutex';
+SELECT SQL_NO_CACHE state FROM INFORMATION_SCHEMA.PROCESSLIST WHERE info='SELECT "try_lock_mutex_query" as action';
+state
+Waiting on query cache mutex
+SET DEBUG_SYNC='now SIGNAL unlock_mutex';
+action
+mutex_locked_query
+action
+try_lock_mutex_query
+SET GLOBAL query_cache_size=0;