diff --git a/query_classifier/query_classifier.cc b/query_classifier/query_classifier.cc
index dfcf8d149..c5ca3e0ba 100644
--- a/query_classifier/query_classifier.cc
+++ b/query_classifier/query_classifier.cc
@@ -67,28 +67,18 @@ extern __thread log_info_t tls_log_info;
 
 #define QTYPE_LESS_RESTRICTIVE_THAN_WRITE(t) (t<QUERY_TYPE_WRITE ? true : false)
 
-static THD* get_or_create_thd_for_parsing(
-        MYSQL* mysql,
-        char*  query_str);
-
-static unsigned long set_client_flags(
-        MYSQL* mysql);
-
-static bool create_parse_tree(
-        THD* thd);
-
-static skygw_query_type_t resolve_query_type(
-        THD* thd);
-
+static THD* get_or_create_thd_for_parsing(MYSQL* mysql, char* query_str);
+static unsigned long set_client_flags(MYSQL* mysql);
+static bool create_parse_tree(THD* thd);
+static skygw_query_type_t resolve_query_type(THD* thd);
 static bool skygw_stmt_causes_implicit_commit(
         LEX*  lex,
         int* autocommit_stmt);
 
-static int is_autocommit_stmt(
-        LEX* lex);
+static int is_autocommit_stmt(LEX* lex);
+static void parsing_info_set_plain_str(void* ptr, char* str);
+static void* skygw_get_affected_tables(void* lexptr);
 
-static void parsing_info_set_plain_str(void* ptr, 
-        char* str);
 
 /**
  * Calls parser for the query includede in the buffer. Creates and adds parsing 
@@ -107,6 +97,11 @@ skygw_query_type_t query_classifier_get_type(
         
         ss_info_dassert(querybuf != NULL, ("querybuf is NULL"));
         
+	if (querybuf == NULL)
+	{
+		succp = false;
+		goto retblock;
+	}
         /** Create parsing info for the query and store it to buffer */
         succp = query_is_parsed(querybuf);
         
@@ -133,6 +128,7 @@ skygw_query_type_t query_classifier_get_type(
                         }
                 }
         }
+retblock:
         return qtype;
 }
 
@@ -158,7 +154,7 @@ bool parse_query (
         /** Do not parse without releasing previous parse info first */
         ss_dassert(!query_is_parsed(querybuf));
          
-        if (query_is_parsed(querybuf))
+        if (querybuf == NULL || query_is_parsed(querybuf))
         {
                 return false;
         }
@@ -225,7 +221,7 @@ bool query_is_parsed(
         GWBUF* buf)
 {
         CHK_GWBUF(buf);
-        return GWBUF_IS_PARSED(buf);
+        return (buf != NULL && GWBUF_IS_PARSED(buf));
 }
 
 
@@ -957,13 +953,25 @@ return_rc:
         return rc;
 }
 
-
+#if defined(NOT_USED)
 char* skygw_query_classifier_get_stmtname(
-        MYSQL* mysql)
+	GWBUF* buf)
 {
+	MYSQL* mysql;
+	
+	if (buf == NULL ||
+		buf->gwbuf_bufobj == NULL ||
+		buf->gwbuf_bufobj->bo_data == NULL ||
+		(mysql = (MYSQL *)((parsing_info_t *)buf->gwbuf_bufobj->bo_data)->pi_handle) == NULL ||
+		mysql->thd == NULL || 
+		(THD *)(mysql->thd))->lex == NULL || 
+		(THD *)(mysql->thd))->lex->prepared_stmt_name == NULL)
+	{
+		return NULL;
+	}
         return ((THD *)(mysql->thd))->lex->prepared_stmt_name.str;
-        
 }
+#endif
 
 /**
  * Get the parse tree from parsed querybuf.
@@ -975,31 +983,29 @@ char* skygw_query_classifier_get_stmtname(
 LEX* get_lex(GWBUF* querybuf)
 {
 
-  parsing_info_t* pi;
-  MYSQL*          mysql;
-  THD*            thd;
-        
-  if (!GWBUF_IS_PARSED(querybuf))
-    {
-      return NULL;
-    }
-  pi = (parsing_info_t *)gwbuf_get_buffer_object_data(querybuf, 
-						      GWBUF_PARSING_INFO);
+	parsing_info_t* pi;
+	MYSQL*          mysql;
+	THD*            thd;
+		
+	if (querybuf == NULL || !GWBUF_IS_PARSED(querybuf))
+	{
+		return NULL;
+	}
+	pi = (parsing_info_t *)gwbuf_get_buffer_object_data(querybuf, 
+							    GWBUF_PARSING_INFO);
 
-  if (pi == NULL)
-    {
-      return NULL;
-    }
-        
-  if ((mysql = (MYSQL *)pi->pi_handle) == NULL || 
-      (thd = (THD *)mysql->thd) == NULL)
-    {
-      ss_dassert(mysql != NULL && 
-		 thd != NULL);
-      return NULL;
-    }
-
-  return thd->lex;
+	if (pi == NULL)
+	{
+		return NULL;
+	}
+		
+	if ((mysql = (MYSQL *)pi->pi_handle) == NULL || 
+		(thd = (THD *)mysql->thd) == NULL)
+	{
+		ss_dassert(mysql != NULL && thd != NULL);
+		return NULL;
+	}
+	return thd->lex;
 }
 
 
@@ -1009,7 +1015,7 @@ LEX* get_lex(GWBUF* querybuf)
  * @param thd Pointer to a valid THD
  * @return Pointer to the head of the TABLE_LIST chain or NULL in case of an error
  */
-void* skygw_get_affected_tables(void* lexptr)
+static void* skygw_get_affected_tables(void* lexptr)
 {
         LEX* lex = (LEX*)lexptr;
         
@@ -1027,87 +1033,93 @@ void* skygw_get_affected_tables(void* lexptr)
 
 /**
  * Reads the parsetree and lists all the affected tables and views in the query.
- * In the case of an error, the size of the table is set to zero and no memory is allocated.
- * The caller must free the allocated memory.
+ * In the case of an error, the size of the table is set to zero and no memory 
+ * is allocated. The caller must free the allocated memory.
  *
  * @param querybuf GWBUF where the table names are extracted from
  * @param tblsize Pointer where the number of tables is written
  * @return Array of null-terminated strings with the table names
  */
-char** skygw_get_table_names(GWBUF* querybuf,int* tblsize, bool fullnames)
+char** skygw_get_table_names(GWBUF* querybuf, int* tblsize, bool fullnames)
 {
-  LEX*			lex;
-  TABLE_LIST*		tbl;
-  int			i = 0,
+	LEX*		lex;
+	TABLE_LIST*	tbl;
+	int		i = 0,
 			currtblsz = 0;
-  char			**tables = NULL,
+	char		**tables = NULL,
 			**tmp = NULL;
 
-  if( (lex = get_lex(querybuf)) == NULL || 
-	  lex->current_select == NULL )
+	if(querybuf == NULL || 
+		tblsize == NULL || 
+		(lex = get_lex(querybuf)) == NULL || 
+		lex->current_select == NULL)
 	{
-      goto retblock;
-    }        
+		goto retblock;
+	}        
 
-  lex->current_select = lex->all_selects_list;
+	lex->current_select = lex->all_selects_list;
 
-  while(lex->current_select){
-    
-    tbl = (TABLE_LIST*)skygw_get_affected_tables(lex);
+	while(lex->current_select)
+	{
+		tbl = (TABLE_LIST*)skygw_get_affected_tables(lex);
 
-    while (tbl) 
-      {
-	if(i >= currtblsz){
-	  
-	  tmp = (char**)malloc(sizeof(char*)*(currtblsz*2+1));
-
-	  if(tmp){
-	    if(currtblsz > 0){
-	      int x;
-	      for(x = 0;x<currtblsz;x++){
-		tmp[x] = tables[x]; 
-	      }
-	      free(tables);
-	    }
-
-	    tables = tmp;
-	    currtblsz = currtblsz*2 + 1;
-
-	  }	  
-	  
-	}
-	if(tmp != NULL){
-		char *catnm = NULL;
-
-		if(fullnames)
+		while (tbl) 
+		{
+			if (i >= currtblsz)
 			{
-				if(tbl->db && strcmp(tbl->db,"skygw_virtual") != 0)
+				tmp = (char**)malloc(sizeof(char*)*(currtblsz*2+1));
+
+				if(tmp)
+				{
+					if(currtblsz > 0)
 					{
-						catnm = (char*)calloc(strlen(tbl->db) + strlen(tbl->table_name) + 2,sizeof(char));
+						int x;
+						for(x = 0; x<currtblsz; x++)
+						{
+							tmp[x] = tables[x]; 
+						}
+						free(tables);
+					}
+					tables = tmp;
+					currtblsz = currtblsz*2 + 1;
+				}
+			}
+			
+			if(tmp != NULL)
+			{
+				char *catnm = NULL;
+				
+				if(fullnames)
+				{
+					if (tbl->db && 
+						strcmp(tbl->db,"skygw_virtual") != 0)
+					{
+						catnm = (char*)calloc(strlen(tbl->db) + 
+							strlen(tbl->table_name) + 
+							2,
+						sizeof(char));
 						strcpy(catnm,tbl->db);
 						strcat(catnm,".");
 						strcat(catnm,tbl->table_name);
 					}
+				}
+			
+				if(catnm)
+				{
+					tables[i++] = catnm;
+				}
+				else
+				{
+					tables[i++] = strdup(tbl->table_name);
+				}
+				tbl=tbl->next_local;
 			}
-	
-		if(catnm)
-			{
-				tables[i++] = catnm;
-			}
-		else
-			{
-				tables[i++] = strdup(tbl->table_name);
-			}
-
-		tbl=tbl->next_local;
-	}
-      }
-    lex->current_select = lex->current_select->next_select_in_list();
-  }
-
- retblock:
-  *tblsize = i;
-  return tables;
+		} /*< while (tbl) */
+		lex->current_select = lex->current_select->next_select_in_list();
+	} /*< while(lex->current_select) */
+retblock:
+	*tblsize = i;
+	return tables;
 }
 
 /**
@@ -1117,52 +1129,70 @@ char** skygw_get_table_names(GWBUF* querybuf,int* tblsize, bool fullnames)
  */
 char* skygw_get_created_table_name(GWBUF* querybuf)
 {
-  LEX* lex;
-  
-  if((lex = get_lex(querybuf)) == NULL)
-    {
-      return NULL;
-    }
+	LEX* lex;
+	
+	if(querybuf == NULL || (lex = get_lex(querybuf)) == NULL)
+	{
+		return NULL;
+	}
 
-  if(lex->create_last_non_select_table && 
-     lex->create_last_non_select_table->table_name){
-    char* name = strdup(lex->create_last_non_select_table->table_name);
-    return name;
-  }else{
-    return NULL;
-  }
-  
+	if (lex->create_last_non_select_table && 
+		lex->create_last_non_select_table->table_name)
+	{
+		char* name = strdup(lex->create_last_non_select_table->table_name);
+		return name;
+	}
+	else
+	{
+		return NULL;
+	}
 }
 
 /**
- * Checks whether the query is a "real" query ie. SELECT,UPDATE,INSERT,DELETE or any variation of these.
- * Queries that affect the underlying database are not considered as real queries and the queries that target
- * specific row or variable data are regarded as the real queries.
+ * Checks whether the query is a "real" query ie. SELECT,UPDATE,INSERT,DELETE or 
+ * any variation of these. Queries that affect the underlying database are not 
+ * considered as real queries and the queries that target specific row or 
+ * variable data are regarded as the real queries.
+ * 
  * @param GWBUF to analyze
+ * 
  * @return true if the query is a real query, otherwise false
  */
 bool skygw_is_real_query(GWBUF* querybuf)
 {
-  LEX* lex = get_lex(querybuf);
-  if(lex){
-    switch(lex->sql_command){
-    case SQLCOM_SELECT:
-      return lex->all_selects_list->table_list.elements > 0;
-    case SQLCOM_UPDATE:
-    case SQLCOM_INSERT:
-    case SQLCOM_INSERT_SELECT:
-    case SQLCOM_DELETE:
-    case SQLCOM_TRUNCATE:
-    case SQLCOM_REPLACE:
-    case SQLCOM_REPLACE_SELECT:
-    case SQLCOM_PREPARE:
-    case SQLCOM_EXECUTE:
-      return true;
-    default:
-      return false;
+	bool succp;
+	LEX* lex;
+	
+	if (querybuf == NULL ||
+		(lex = get_lex(querybuf)) == NULL)
+	{
+		succp = false;
+		goto retblock;
 	}
-  }
-  return false;
+	switch(lex->sql_command) {
+		case SQLCOM_SELECT:
+			succp = lex->all_selects_list->table_list.elements > 0;
+			goto retblock;
+			break;
+		case SQLCOM_UPDATE:
+		case SQLCOM_INSERT:
+		case SQLCOM_INSERT_SELECT:
+		case SQLCOM_DELETE:
+		case SQLCOM_TRUNCATE:
+		case SQLCOM_REPLACE:
+		case SQLCOM_REPLACE_SELECT:
+		case SQLCOM_PREPARE:
+		case SQLCOM_EXECUTE:
+			succp = true;
+			goto retblock;
+			break;
+		default:
+			succp = false;
+			goto retblock;
+			break;
+	}
+retblock:
+	return succp;
 }
 
 
@@ -1173,10 +1203,11 @@ bool skygw_is_real_query(GWBUF* querybuf)
  */
 bool is_drop_table_query(GWBUF* querybuf)
 {
-  LEX* lex;
+	LEX* lex;
         
-  return (lex = get_lex(querybuf)) != NULL &&
-	  lex->sql_command == SQLCOM_DROP_TABLE;
+	return (querybuf != NULL &&
+		(lex = get_lex(querybuf)) != NULL &&
+		lex->sql_command == SQLCOM_DROP_TABLE);
 }
 
 /**
@@ -1202,7 +1233,8 @@ char* skygw_get_canonical(
         Item*           item;
         char*           querystr;
         
-        if (!GWBUF_IS_PARSED(querybuf))
+        if (querybuf == NULL ||
+		!GWBUF_IS_PARSED(querybuf))
         {
                 querystr = NULL;
                 goto retblock;
@@ -1339,25 +1371,30 @@ retblock:
 void parsing_info_done(
         void* ptr)
 {
-        parsing_info_t* pi = (parsing_info_t *)ptr;
+        parsing_info_t* pi;
+	
+	if (ptr)
+	{
+		pi = (parsing_info_t *)ptr;
         
-        if (pi->pi_handle != NULL)
-        {
-                MYSQL* mysql = (MYSQL *)pi->pi_handle;
-                
-                if (mysql->thd != NULL)
-                {
-                        (*mysql->methods->free_embedded_thd)(mysql);
-                        mysql->thd = NULL;
-                }
-                mysql_close(mysql);
-        }
-        /** Free plain text query string */
-        if (pi->pi_query_plain_str != NULL)
-        {
-                free(pi->pi_query_plain_str);
-        }
-        free(pi);
+		if (pi->pi_handle != NULL)
+		{
+			MYSQL* mysql = (MYSQL *)pi->pi_handle;
+			
+			if (mysql->thd != NULL)
+			{
+				(*mysql->methods->free_embedded_thd)(mysql);
+				mysql->thd = NULL;
+			}
+			mysql_close(mysql);
+		}
+		/** Free plain text query string */
+		if (pi->pi_query_plain_str != NULL)
+		{
+			free(pi->pi_query_plain_str);
+		}
+		free(pi);
+	}
 }
 
 /**
diff --git a/query_classifier/query_classifier.h b/query_classifier/query_classifier.h
index 3600bce5a..5837b81c7 100644
--- a/query_classifier/query_classifier.h
+++ b/query_classifier/query_classifier.h
@@ -83,12 +83,13 @@ typedef struct parsing_info_st {
 skygw_query_type_t query_classifier_get_type(GWBUF* querybuf);
 
 /** Free THD context and close MYSQL */
-char*           skygw_query_classifier_get_stmtname(MYSQL* mysql);
+#if defined(NOT_USED)
+char*           skygw_query_classifier_get_stmtname(GWBUF* buf);
+#endif
 char*		skygw_get_created_table_name(GWBUF* querybuf);
 bool		is_drop_table_query(GWBUF* querybuf);
 bool		skygw_is_real_query(GWBUF* querybuf);
-void*		skygw_get_affected_tables(void* lexptr);
-char**		skygw_get_table_names(GWBUF* querybuf,int* tblsize,bool fullnames);
+char**		skygw_get_table_names(GWBUF* querybuf, int* tblsize, bool fullnames);
 char*           skygw_get_canonical(GWBUF* querybuf);
 bool            parse_query (GWBUF* querybuf);
 parsing_info_t* parsing_info_init(void (*donefun)(void *));