diff --git a/include/c_tokenizer.h b/include/c_tokenizer.h
index abe0fdb30d..4444ca2e6a 100644
--- a/include/c_tokenizer.h
+++ b/include/c_tokenizer.h
@@ -1,5 +1,3 @@
-/* c_tokenizer.h */
-// some code borrowed from http://www.cplusplus.com/faq/sequences/strings/split/
 
 #pragma once
 #ifndef C_TOKENIZER_H
@@ -34,7 +32,6 @@ const char* free_tokenizer( tokenizer_t* tokenizer );
 const char* tokenize( tokenizer_t* tokenizer );
 char * mysql_query_digest_first_stage(const char* const q, int q_len, char** const fst_cmnt, char* const buf);
 char * mysql_query_digest_second_stage(const char* const q, int q_len, char** const fst_cmnt, char* const buf);
-char * mysql_query_digest_and_first_comment(char *s , int len , char **first_comment, char *buf);
 char * mysql_query_digest_and_first_comment_2(const char* const q, int q_len, char** const fst_cmnt, char* const buf);
 char * mysql_query_digest_and_first_comment_one_it(char *s , int len , char **first_comment, char *buf);
 char * mysql_query_strip_comments(char *s , int len);
diff --git a/lib/c_tokenizer.cpp b/lib/c_tokenizer.cpp
index c468e0b185..5b35ef0fb3 100644
--- a/lib/c_tokenizer.cpp
+++ b/lib/c_tokenizer.cpp
@@ -1,6 +1,3 @@
-/* c_tokenizer.c */
-// Borrowed from http://www.cplusplus.com/faq/sequences/strings/split/
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -234,591 +231,6 @@ static inline void replace_with_q_mark(
 	}
 }
 
-char *mysql_query_digest_and_first_comment(char *s, int _len, char **first_comment, char *buf){
-	int i = 0;
-
-	char cur_comment[FIRST_COMMENT_MAX_LENGTH];
-	cur_comment[0]=0;
-	int ccl=0;
-	int cmd=0;
-
-	int len = _len;
-	if (_len > mysql_thread___query_digests_max_query_length) {
-		len = mysql_thread___query_digests_max_query_length;
-	}
-	char *r = buf;
-	if (r==NULL) {
-		r = (char *) malloc(len + SIZECHAR);
-	}
-	char *p_r = r;
-	char *p_r_t = r;
-
-	char prev_char = 0;
-	char qutr_char = 0;
-
-	char flag = 0;
-	char fc=0;
-	int fc_len=0;
-
-	char fns=0;
-
-	bool lowercase=0;
-	bool replace_null=0;
-	bool replace_number=0;
-
-	char grouping_digest=0;
-	char grouping_limit_exceeded=0;
-	int grouping_count=0;
-	int grouping_lim = mysql_thread___query_digests_grouping_limit;
-
-	lowercase=mysql_thread___query_digests_lowercase;
-	replace_null = mysql_thread___query_digests_replace_null;
-	replace_number = mysql_thread___query_digests_no_digits;
-
-	while(i < len)
-	{
-		// Handy for debugging purposes
-		// ============================
-		// printf(
-		// 	"state-1: { flag: `%d`, prev_char: `%c`, s: `%s`, p_r: `%s`, r: `%s`}\n",
-		// 	flag, prev_char, s, p_r, r
-		// );
-		// ============================
-
-		// =================================================
-		// START - read token char and set flag what's going on.
-		// =================================================
-		if(flag == 0)
-		{
-			// store current position
-			p_r_t = p_r;
-
-			// comment type 1 - start with '/*'
-			if(prev_char == '/' && *s == '*')
-			{
-				ccl=0;
-				flag = 1;
-				if (i != (len-1) && *(s+1)=='!')
-					cmd=1;
-			}
-
-			// comment type 2 - start with '#'
-			else if(*s == '#')
-			{
-				flag = 2;
-			}
-
-			// comment type 3 - start with '--'
-
-			// NOTE: Looks like the general rule for parsing comments of this type could simply be:
-			//
-			//  - `.*--.*` which could be translated into `(*s == '-' && *(s+1) == '-')`.
-			//
-			// But this can not hold, since the first '-' could have been consumed previously, for example
-			// during the parsing of a digit:
-			//
-			// - `select 1.1-- final_comment\n`
-			//
-			// For this reason 'prev_char' needs to be checked too when searching for the `--` pattern.
-			else if(i != (len-1) && prev_char == '-' && *s == '-' && ((*(s+1)==' ') || (*(s+1)=='\n') || (*(s+1)=='\r') || (*(s+1)=='\t') ))
-			{
-				flag = 3;
-			}
-
-			// Previous character can be a consumed ' ' instead of '-' as in the previous case, for this
-			// reason, we need to look ahead for '--'.
-			//
-			// NOTE: There is no reason for not checking for the subsequent space char that should follow
-			// the '-- ', otherwise we would consider valid queries as `SELECT --1` like comments.
-			else if (i != (len-1) && *s == '-' && (*(s+1)=='-')) {
-				if (prev_char != '-') {
-					flag = 3;
-				}
-				else if (i==0) {
-					flag = 3;
-				}
-			}
-
-			// string - start with '
-			else if(*s == '\'' || *s == '"')
-			{
-				flag = 4;
-				qutr_char = *s;
-			}
-
-			// may be digit - start with digit
-			else if(is_token_char(prev_char) && is_digit_char(*s))
-			{
-				flag = 5;
-				if(len == i+1)
-					continue;
-			}
-
-			// not above case - remove duplicated space char
-			else
-			{
-				flag = 0;
-				if (fns==0 && is_space_char(*s)) {
-					s++;
-					i++;
-					continue;
-				}
-				if (fns==0) fns=1;
-				if(is_space_char(prev_char) && is_space_char(*s)){
-					prev_char = ' ';
-					*p_r = ' ';
-					s++;
-					i++;
-					continue;
-				}
-				if (replace_number) {
-					if (!is_digit_char(prev_char) && is_digit_char(*s)) {
-						*p_r++ = '?';
-						while(*s != '\0' && is_digit_char(*s)) {
-							s++;
-							i++;
-						}
-					}
-				}
-				{
-					char* p = p_r - 2;
-					// suppress spaces before arithmetic operators
-					if (p >= r && is_space_char(prev_char) && is_arithmetic_op(*s)) {
-						if (*p == '?') {
-							prev_char = *s;
-							--p_r;
-							*p_r++ = *s;
-							s++;
-							i++;
-							continue;
-						}
-					}
-					// suppress spaces before and after commas
-					if (p >= r && is_space_char(prev_char) && ((*s == ',') || (*p == ','))) {
-						if (*s == ',') {
-							--p_r;
-							// only copy the comma if we are not grouping a query
-							if (!grouping_limit_exceeded) {
-								*p_r++ = *s;
-							}
-							prev_char = ',';
-							s++;
-							i++;
-						} else {
-							prev_char = ',';
-							--p_r;
-						}
-						continue;
-					}
-					// suppress spaces before closing brackets when grouping or mark is present
-					if (p >= r && (*p == '.' || *p == '?') && is_space_char(prev_char) && (*s == ')')) {
-						prev_char = *s;
-						--p_r;
-						*p_r++ = *s;
-						s++;
-						i++;
-						continue;
-					}
-				}
-				if (replace_null) {
-				if (*s == 'n' || *s == 'N') { // we search for NULL , #2171
-					if (i && is_token_char(prev_char)) {
-						if (len>=4) {
-							if (i<len-3) {
-								// it is only 4 chars, let's skip strncasecmp
-								if (*(s+1) == 'u' || *(s+1) == 'U') {
-									if (*(s+2) == 'l' || *(s+2) == 'L') {
-										if (*(s+3) == 'l' || *(s+3) == 'L') {
-											if (i==len-4) {
-												// replace spaces before NULL values
-												if (*(p_r - 1) == ' ' && is_token_char(*(p_r - 2))) {
-													p_r--;
-												}
-
-												replace_with_q_mark(
-													grouping_digest, grouping_lim, &grouping_count,
-													&p_r, &grouping_limit_exceeded
-												);
-
-												*p_r = 0;
-												return r;
-											} else {
-												if (is_token_char(*(s+4))){
-													// replace spaces before NULL values
-													if (*(p_r - 1) == ' ' && is_token_char(*(p_r - 2))) {
-														p_r--;
-													}
-
-													replace_with_q_mark(
-														grouping_digest, grouping_lim, &grouping_count,
-														&p_r, &grouping_limit_exceeded
-													);
-
-													s+=4;
-													i+=4;
-												}
-											}
-										}
-									}
-								}
-							}
-						}
-					}
-				}
-				}
-			}
-		}
-
-		// =================================================
-		// PROCESS and FINISH - do something on each case
-		// =================================================
-		else
-		{
-			// --------
-			// comment
-			// --------
-			if (flag == 1) {
-				if (cmd) {
-					if (ccl<FIRST_COMMENT_MAX_LENGTH-1) {
-						cur_comment[ccl]=*s;
-						ccl++;
-					}
-				}
-				if (fc==0) {
-					fc=1;
-				}
-				if (fc==1) {
-					if (fc_len<FIRST_COMMENT_MAX_LENGTH-1) {
-						if (*first_comment==NULL) {
-							*first_comment=(char *)malloc(FIRST_COMMENT_MAX_LENGTH);
-							*(*first_comment + FIRST_COMMENT_MAX_LENGTH - 1) = 0;
-						}
-						char *c=*first_comment+fc_len;
-						*c = !is_space_char(*s) ? *s : ' ';
-						fc_len++;
-					}
-					if (prev_char == '*' && *s == '/') {
-						if (fc_len>=2) fc_len-=2;
-						char *c=*first_comment+fc_len;
-						*c=0;
-						//*first_comment[fc_len]=0;
-						fc=2;
-					}
-				}
-			}
-			if(
-				// comment type 1 - /* .. */
-				(flag == 1 && prev_char == '*' && *s == '/') ||
-
-				// comment type 2 - # ... \n
-				(flag == 2 && (*s == '\n' || *s == '\r' || (i == len - 1) ))
-				||
-				// comment type 3 - -- ... \n
-				(flag == 3 && (*s == '\n' || *s == '\r' || (i == len -1) ))
-			)
-			{
-				p_r = p_r_t;
-				if (flag == 1 || (i == len -1)) {
-					p_r -= SIZECHAR;
-				}
-				if (cmd) {
-					cur_comment[ccl]=0;
-					if (ccl>=2) {
-						ccl-=2;
-						cur_comment[ccl]=0;
-						char el=0;
-						int fcc=0;
-						while (el==0 && fcc<ccl ) {
-							switch (cur_comment[fcc]) {
-								case '/':
-								case '*':
-								case '!':
-								case '0':
-								case '1':
-								case '2':
-								case '3':
-								case '4':
-								case '5':
-								case '6':
-								case '7':
-								case '8':
-								case '9':
-								case ' ':
-									fcc++;
-									break;
-								default:
-									el=1;
-									break;
-							}
-						}
-						if (el) {
-							memcpy(p_r,cur_comment+fcc,ccl-fcc);
-							p_r+=(ccl-fcc);
-							*p_r++=' ';
-						}
-					}
-					cmd=0;
-				}
-				if (flag == 1 && prev_char == '*' && *s == '/') {
-					if (r != p_r && *p_r != ' ') { // not at the beginning, and previous char is not ' '
-						*p_r++ = ' ';
-					}
-				}
-				prev_char = ' ';
-				flag = 0;
-				s++;
-				i++;
-				continue;
-			}
-
-			// --------
-			// string
-			// --------
-			else if(flag == 4)
-			{
-				// Last char process
-				if(len == i + 1)
-				{
-					char *_p = p_r_t;
-					_p-=3;
-					p_r = p_r_t;
-					if ( _p >= r && ( *(_p+2) == '-' || *(_p+2) == '+') ) {
-						if  (
-							( *(_p+1) == ',' ) || ( *(_p+1) == '(' ) ||
-							( ( *(_p+1) == ' ' ) && ( *_p == ',' || *_p == '(' ) )
-						) {
-							p_r--;
-						}
-					}
-
-					replace_with_q_mark(
-						grouping_digest, grouping_lim, &grouping_count, &p_r, &grouping_limit_exceeded
-					);
-
-					flag = 0;
-					break;
-				}
-
-				// need to be ignored case
-				if(p_r > p_r_t + SIZECHAR)
-				{
-					if(
-						(prev_char == '\\' && *s == '\\') ||		// to process '\\\\', '\\'
-						(prev_char == '\\' && *s == qutr_char) ||	// to process '\''
-						(prev_char == qutr_char && *s == qutr_char)	// to process ''''
-					)
-					{
-						prev_char = 'X';
-						s++;
-						i++;
-						continue;
-					}
-				}
-
-				// satisfied closing string - swap string to ?
-				if(*s == qutr_char && (len == i+1 || *(s + SIZECHAR) != qutr_char))
-				{
-					char *_p = p_r_t;
-					_p-=3;
-					p_r = p_r_t;
-					if ( _p >= r && ( *(_p+2) == '-' || *(_p+2) == '+') ) {
-						if  (
-							( *(_p+1) == ',' ) || ( *(_p+1) == '(' ) ||
-							( ( *(_p+1) == ' ' ) && ( *_p == ',' || *_p == '(' ) )
-						) {
-							p_r--;
-						}
-					}
-
-					// Remove spaces before each literal found
-					if ( _p >= r && is_space_char(*(_p + 2)) && !is_normal_char(*(_p + 1))) {
-						if ( _p >= r && ( *(_p+3) == '\''|| *(_p+3) == '"' )) {
-							p_r--;
-						}
-					}
-
-					replace_with_q_mark(
-						grouping_digest, grouping_lim, &grouping_count, &p_r, &grouping_limit_exceeded
-					);
-
-					prev_char = qutr_char;
-					qutr_char = 0;
-					flag = 0;
-					if(i < len)
-						s++;
-					i++;
-					continue;
-				}
-			}
-
-			// --------
-			// digit
-			// --------
-			else if(flag == 5)
-			{
-				// last single char
-				if(p_r_t == p_r)
-				{
-					char *_p = p_r_t;
-					_p-=3;
-					if ( _p >= r && ( *(_p+2) == '-' || *(_p+2) == '+') ) {
-						if  (
-							( *(_p+1) == ',' ) || ( *(_p+1) == '(' ) ||
-							( ( *(_p+1) == ' ' ) && ( *_p == ',' || *_p == '(' ) )
-						) {
-							p_r--;
-						}
-					}
-					if ( _p >= r && is_space_char(*(_p + 2))) {
-						if ( _p >= r && ( *(_p+1) == '-' || *(_p+1) == '+' || *(_p+1) == '*' || *(_p+1) == '/' || *(_p+1) == '%' || *(_p+1) == ',')) {
-							p_r--;
-						}
-					}
-					*p_r++ = '?';
-					i++;
-					continue;
-				}
-
-				// is float
-				if (*s == '.' || *s == 'e' || ((*s == '+' || *s == '-') && prev_char == 'e')) {
-					prev_char = *s;
-					i++;
-					s++;
-					continue;
-				}
-
-				// token char or last char
-				if(is_token_char(*s) || len == i+1)
-				{
-					if(is_digit_string(p_r_t, p_r))
-					{
-						char *_p = p_r_t;
-						_p-=3;
-						p_r = p_r_t;
-						// remove symbol and keep parenthesis or comma
-						if ( _p >= r && ( *(_p+2) == '-' || *(_p+2) == '+') ) {
-							if  (
-								( *(_p+1) == ',' ) || ( *(_p+1) == '(' ) ||
-								( ( *(_p+1) == ' ' ) && ( *_p == ',' || *_p == '(' ) )
-							) {
-								p_r--;
-							}
-						}
-
-						// Remove spaces before number counting with possible '.' presence
-						if (_p >= r && *_p == '.' && (*(_p + 1) == ' ' || *(_p + 1) == '.') && (*(_p+2) == '-' || *(_p+2) == '+') ) {
-							if (*(_p + 1) == ' ') {
-								p_r--;
-							}
-							p_r--;
-						}
-
-						// Remove spaces after a opening bracket when followed by a number
-						if (_p >= r && *(_p+1) == '(' && *(_p+2) == ' ') {
-							p_r--;
-						}
-
-						// Remove spaces before number
-						if ( _p >= r && is_space_char(*(_p + 2))) {
-							// A point can be found prior to a number in case of query grouping
-							if ( _p >= r && ( *(_p+1) == '-' || *(_p+1) == '+' || *(_p+1) == '*' || *(_p+1) == '/' || *(_p+1) == '%' || *(_p+1) == ',' || *(_p+1) == '.')) {
-								p_r--;
-							}
-						}
-
-						replace_with_q_mark(
-							grouping_digest, grouping_lim, &grouping_count, &p_r, &grouping_limit_exceeded
-						);
-
-						if(len == i+1)
-						{
-							if(is_token_char(*s))
-								*p_r++ = *s;
-							i++;
-							continue;
-						}
-					} else {
-						// collapse any digits found in the string
-						if (replace_number) {
-							int str_len = p_r - p_r_t + 1;
-							int collapsed = 0;
-
-							for (int j = 0; j < str_len; j++) {
-								char* const c_p_r_t = ((char*)p_r_t + j);
-								char* const n_p_r_t = ((char*)p_r_t + j + 1);
-
-								if (is_digit_char(*c_p_r_t) && is_digit_char(*n_p_r_t)) {
-									memmove(c_p_r_t, c_p_r_t + 1, str_len - j);
-									collapsed += 1;
-								}
-							}
-
-							p_r -= collapsed;
-
-							int new_str_len = p_r - p_r_t + 1;
-							for (int j = 0; j < new_str_len; j++) {
-								char* const c_p_r_t = ((char*)p_r_t + j);
-								if (is_digit_char(*c_p_r_t)) {
-									*c_p_r_t = '?';
-								}
-							}
-						}
-					}
-
-					flag = 0;
-				}
-			}
-		}
-
-		// =================================================
-		// COPY CHAR
-		// =================================================
-		// convert every space char to ' '
-		if (*s == ')') {
-			if (grouping_digest > 0) {
-				grouping_digest -= 1;
-			};
-			grouping_count = 0;
-			grouping_limit_exceeded = 0;
-		}
-
-		if (lowercase==0) {
-			*p_r++ = !is_space_char(*s) ? *s : ' ';
-		} else {
-			*p_r++ = !is_space_char(*s) ? (tolower(*s)) : ' ';
-		}
-
-		if (*s == '(') {
-			grouping_digest += 1;
-			grouping_count = 0;
-			grouping_limit_exceeded = 0;
-		}
-
-		prev_char = *s++;
-
-		i++;
-	}
-
-	// remove a trailing space
-	if (p_r>r) {
-		char *e=p_r;
-		e--;
-		if (*e==' ') {
-			*e=0;
-			// maybe 2 trailing spaces . It happens with comments
-			e--;
-			if (*e==' ') {
-				*e=0;
-			}
-		}
-	}
-
-	*p_r = 0;
-
-	// process query stats
-	return r;
-}
-
 /**
  * @brief Struct for holding all the configuration options used for query digests generation.
  */
diff --git a/lib/c_tokenizer_legacy.cpp b/lib/c_tokenizer_legacy.cpp
new file mode 100644
index 0000000000..ae93027afe
--- /dev/null
+++ b/lib/c_tokenizer_legacy.cpp
@@ -0,0 +1,588 @@
+/*
+	this file is here only for reference.
+	It includes the old mysql_query_digest_and_first_comment() , outdated since ProxySQL 2.4.0
+*/
+char *mysql_query_digest_and_first_comment(char *s, int _len, char **first_comment, char *buf){
+	int i = 0;
+
+	char cur_comment[FIRST_COMMENT_MAX_LENGTH];
+	cur_comment[0]=0;
+	int ccl=0;
+	int cmd=0;
+
+	int len = _len;
+	if (_len > mysql_thread___query_digests_max_query_length) {
+		len = mysql_thread___query_digests_max_query_length;
+	}
+	char *r = buf;
+	if (r==NULL) {
+		r = (char *) malloc(len + SIZECHAR);
+	}
+	char *p_r = r;
+	char *p_r_t = r;
+
+	char prev_char = 0;
+	char qutr_char = 0;
+
+	char flag = 0;
+	char fc=0;
+	int fc_len=0;
+
+	char fns=0;
+
+	bool lowercase=0;
+	bool replace_null=0;
+	bool replace_number=0;
+
+	char grouping_digest=0;
+	char grouping_limit_exceeded=0;
+	int grouping_count=0;
+	int grouping_lim = mysql_thread___query_digests_grouping_limit;
+
+	lowercase=mysql_thread___query_digests_lowercase;
+	replace_null = mysql_thread___query_digests_replace_null;
+	replace_number = mysql_thread___query_digests_no_digits;
+
+	while(i < len)
+	{
+		// Handy for debugging purposes
+		// ============================
+		// printf(
+		// 	"state-1: { flag: `%d`, prev_char: `%c`, s: `%s`, p_r: `%s`, r: `%s`}\n",
+		// 	flag, prev_char, s, p_r, r
+		// );
+		// ============================
+
+		// =================================================
+		// START - read token char and set flag what's going on.
+		// =================================================
+		if(flag == 0)
+		{
+			// store current position
+			p_r_t = p_r;
+
+			// comment type 1 - start with '/*'
+			if(prev_char == '/' && *s == '*')
+			{
+				ccl=0;
+				flag = 1;
+				if (i != (len-1) && *(s+1)=='!')
+					cmd=1;
+			}
+
+			// comment type 2 - start with '#'
+			else if(*s == '#')
+			{
+				flag = 2;
+			}
+
+			// comment type 3 - start with '--'
+
+			// NOTE: Looks like the general rule for parsing comments of this type could simply be:
+			//
+			//  - `.*--.*` which could be translated into `(*s == '-' && *(s+1) == '-')`.
+			//
+			// But this can not hold, since the first '-' could have been consumed previously, for example
+			// during the parsing of a digit:
+			//
+			// - `select 1.1-- final_comment\n`
+			//
+			// For this reason 'prev_char' needs to be checked too when searching for the `--` pattern.
+			else if(i != (len-1) && prev_char == '-' && *s == '-' && ((*(s+1)==' ') || (*(s+1)=='\n') || (*(s+1)=='\r') || (*(s+1)=='\t') ))
+			{
+				flag = 3;
+			}
+
+			// Previous character can be a consumed ' ' instead of '-' as in the previous case, for this
+			// reason, we need to look ahead for '--'.
+			//
+			// NOTE: There is no reason for not checking for the subsequent space char that should follow
+			// the '-- ', otherwise we would consider valid queries as `SELECT --1` like comments.
+			else if (i != (len-1) && *s == '-' && (*(s+1)=='-')) {
+				if (prev_char != '-') {
+					flag = 3;
+				}
+				else if (i==0) {
+					flag = 3;
+				}
+			}
+
+			// string - start with '
+			else if(*s == '\'' || *s == '"')
+			{
+				flag = 4;
+				qutr_char = *s;
+			}
+
+			// may be digit - start with digit
+			else if(is_token_char(prev_char) && is_digit_char(*s))
+			{
+				flag = 5;
+				if(len == i+1)
+					continue;
+			}
+
+			// not above case - remove duplicated space char
+			else
+			{
+				flag = 0;
+				if (fns==0 && is_space_char(*s)) {
+					s++;
+					i++;
+					continue;
+				}
+				if (fns==0) fns=1;
+				if(is_space_char(prev_char) && is_space_char(*s)){
+					prev_char = ' ';
+					*p_r = ' ';
+					s++;
+					i++;
+					continue;
+				}
+				if (replace_number) {
+					if (!is_digit_char(prev_char) && is_digit_char(*s)) {
+						*p_r++ = '?';
+						while(*s != '\0' && is_digit_char(*s)) {
+							s++;
+							i++;
+						}
+					}
+				}
+				{
+					char* p = p_r - 2;
+					// suppress spaces before arithmetic operators
+					if (p >= r && is_space_char(prev_char) && is_arithmetic_op(*s)) {
+						if (*p == '?') {
+							prev_char = *s;
+							--p_r;
+							*p_r++ = *s;
+							s++;
+							i++;
+							continue;
+						}
+					}
+					// suppress spaces before and after commas
+					if (p >= r && is_space_char(prev_char) && ((*s == ',') || (*p == ','))) {
+						if (*s == ',') {
+							--p_r;
+							// only copy the comma if we are not grouping a query
+							if (!grouping_limit_exceeded) {
+								*p_r++ = *s;
+							}
+							prev_char = ',';
+							s++;
+							i++;
+						} else {
+							prev_char = ',';
+							--p_r;
+						}
+						continue;
+					}
+					// suppress spaces before closing brackets when grouping or mark is present
+					if (p >= r && (*p == '.' || *p == '?') && is_space_char(prev_char) && (*s == ')')) {
+						prev_char = *s;
+						--p_r;
+						*p_r++ = *s;
+						s++;
+						i++;
+						continue;
+					}
+				}
+				if (replace_null) {
+				if (*s == 'n' || *s == 'N') { // we search for NULL , #2171
+					if (i && is_token_char(prev_char)) {
+						if (len>=4) {
+							if (i<len-3) {
+								// it is only 4 chars, let's skip strncasecmp
+								if (*(s+1) == 'u' || *(s+1) == 'U') {
+									if (*(s+2) == 'l' || *(s+2) == 'L') {
+										if (*(s+3) == 'l' || *(s+3) == 'L') {
+											if (i==len-4) {
+												// replace spaces before NULL values
+												if (*(p_r - 1) == ' ' && is_token_char(*(p_r - 2))) {
+													p_r--;
+												}
+
+												replace_with_q_mark(
+													grouping_digest, grouping_lim, &grouping_count,
+													&p_r, &grouping_limit_exceeded
+												);
+
+												*p_r = 0;
+												return r;
+											} else {
+												if (is_token_char(*(s+4))){
+													// replace spaces before NULL values
+													if (*(p_r - 1) == ' ' && is_token_char(*(p_r - 2))) {
+														p_r--;
+													}
+
+													replace_with_q_mark(
+														grouping_digest, grouping_lim, &grouping_count,
+														&p_r, &grouping_limit_exceeded
+													);
+
+													s+=4;
+													i+=4;
+												}
+											}
+										}
+									}
+								}
+							}
+						}
+					}
+				}
+				}
+			}
+		}
+
+		// =================================================
+		// PROCESS and FINISH - do something on each case
+		// =================================================
+		else
+		{
+			// --------
+			// comment
+			// --------
+			if (flag == 1) {
+				if (cmd) {
+					if (ccl<FIRST_COMMENT_MAX_LENGTH-1) {
+						cur_comment[ccl]=*s;
+						ccl++;
+					}
+				}
+				if (fc==0) {
+					fc=1;
+				}
+				if (fc==1) {
+					if (fc_len<FIRST_COMMENT_MAX_LENGTH-1) {
+						if (*first_comment==NULL) {
+							*first_comment=(char *)malloc(FIRST_COMMENT_MAX_LENGTH);
+							*(*first_comment + FIRST_COMMENT_MAX_LENGTH - 1) = 0;
+						}
+						char *c=*first_comment+fc_len;
+						*c = !is_space_char(*s) ? *s : ' ';
+						fc_len++;
+					}
+					if (prev_char == '*' && *s == '/') {
+						if (fc_len>=2) fc_len-=2;
+						char *c=*first_comment+fc_len;
+						*c=0;
+						//*first_comment[fc_len]=0;
+						fc=2;
+					}
+				}
+			}
+			if(
+				// comment type 1 - /* .. */
+				(flag == 1 && prev_char == '*' && *s == '/') ||
+
+				// comment type 2 - # ... \n
+				(flag == 2 && (*s == '\n' || *s == '\r' || (i == len - 1) ))
+				||
+				// comment type 3 - -- ... \n
+				(flag == 3 && (*s == '\n' || *s == '\r' || (i == len -1) ))
+			)
+			{
+				p_r = p_r_t;
+				if (flag == 1 || (i == len -1)) {
+					p_r -= SIZECHAR;
+				}
+				if (cmd) {
+					cur_comment[ccl]=0;
+					if (ccl>=2) {
+						ccl-=2;
+						cur_comment[ccl]=0;
+						char el=0;
+						int fcc=0;
+						while (el==0 && fcc<ccl ) {
+							switch (cur_comment[fcc]) {
+								case '/':
+								case '*':
+								case '!':
+								case '0':
+								case '1':
+								case '2':
+								case '3':
+								case '4':
+								case '5':
+								case '6':
+								case '7':
+								case '8':
+								case '9':
+								case ' ':
+									fcc++;
+									break;
+								default:
+									el=1;
+									break;
+							}
+						}
+						if (el) {
+							memcpy(p_r,cur_comment+fcc,ccl-fcc);
+							p_r+=(ccl-fcc);
+							*p_r++=' ';
+						}
+					}
+					cmd=0;
+				}
+				if (flag == 1 && prev_char == '*' && *s == '/') {
+					if (r != p_r && *p_r != ' ') { // not at the beginning, and previous char is not ' '
+						*p_r++ = ' ';
+					}
+				}
+				prev_char = ' ';
+				flag = 0;
+				s++;
+				i++;
+				continue;
+			}
+
+			// --------
+			// string
+			// --------
+			else if(flag == 4)
+			{
+				// Last char process
+				if(len == i + 1)
+				{
+					char *_p = p_r_t;
+					_p-=3;
+					p_r = p_r_t;
+					if ( _p >= r && ( *(_p+2) == '-' || *(_p+2) == '+') ) {
+						if  (
+							( *(_p+1) == ',' ) || ( *(_p+1) == '(' ) ||
+							( ( *(_p+1) == ' ' ) && ( *_p == ',' || *_p == '(' ) )
+						) {
+							p_r--;
+						}
+					}
+
+					replace_with_q_mark(
+						grouping_digest, grouping_lim, &grouping_count, &p_r, &grouping_limit_exceeded
+					);
+
+					flag = 0;
+					break;
+				}
+
+				// need to be ignored case
+				if(p_r > p_r_t + SIZECHAR)
+				{
+					if(
+						(prev_char == '\\' && *s == '\\') ||		// to process '\\\\', '\\'
+						(prev_char == '\\' && *s == qutr_char) ||	// to process '\''
+						(prev_char == qutr_char && *s == qutr_char)	// to process ''''
+					)
+					{
+						prev_char = 'X';
+						s++;
+						i++;
+						continue;
+					}
+				}
+
+				// satisfied closing string - swap string to ?
+				if(*s == qutr_char && (len == i+1 || *(s + SIZECHAR) != qutr_char))
+				{
+					char *_p = p_r_t;
+					_p-=3;
+					p_r = p_r_t;
+					if ( _p >= r && ( *(_p+2) == '-' || *(_p+2) == '+') ) {
+						if  (
+							( *(_p+1) == ',' ) || ( *(_p+1) == '(' ) ||
+							( ( *(_p+1) == ' ' ) && ( *_p == ',' || *_p == '(' ) )
+						) {
+							p_r--;
+						}
+					}
+
+					// Remove spaces before each literal found
+					if ( _p >= r && is_space_char(*(_p + 2)) && !is_normal_char(*(_p + 1))) {
+						if ( _p >= r && ( *(_p+3) == '\''|| *(_p+3) == '"' )) {
+							p_r--;
+						}
+					}
+
+					replace_with_q_mark(
+						grouping_digest, grouping_lim, &grouping_count, &p_r, &grouping_limit_exceeded
+					);
+
+					prev_char = qutr_char;
+					qutr_char = 0;
+					flag = 0;
+					if(i < len)
+						s++;
+					i++;
+					continue;
+				}
+			}
+
+			// --------
+			// digit
+			// --------
+			else if(flag == 5)
+			{
+				// last single char
+				if(p_r_t == p_r)
+				{
+					char *_p = p_r_t;
+					_p-=3;
+					if ( _p >= r && ( *(_p+2) == '-' || *(_p+2) == '+') ) {
+						if  (
+							( *(_p+1) == ',' ) || ( *(_p+1) == '(' ) ||
+							( ( *(_p+1) == ' ' ) && ( *_p == ',' || *_p == '(' ) )
+						) {
+							p_r--;
+						}
+					}
+					if ( _p >= r && is_space_char(*(_p + 2))) {
+						if ( _p >= r && ( *(_p+1) == '-' || *(_p+1) == '+' || *(_p+1) == '*' || *(_p+1) == '/' || *(_p+1) == '%' || *(_p+1) == ',')) {
+							p_r--;
+						}
+					}
+					*p_r++ = '?';
+					i++;
+					continue;
+				}
+
+				// is float
+				if (*s == '.' || *s == 'e' || ((*s == '+' || *s == '-') && prev_char == 'e')) {
+					prev_char = *s;
+					i++;
+					s++;
+					continue;
+				}
+
+				// token char or last char
+				if(is_token_char(*s) || len == i+1)
+				{
+					if(is_digit_string(p_r_t, p_r))
+					{
+						char *_p = p_r_t;
+						_p-=3;
+						p_r = p_r_t;
+						// remove symbol and keep parenthesis or comma
+						if ( _p >= r && ( *(_p+2) == '-' || *(_p+2) == '+') ) {
+							if  (
+								( *(_p+1) == ',' ) || ( *(_p+1) == '(' ) ||
+								( ( *(_p+1) == ' ' ) && ( *_p == ',' || *_p == '(' ) )
+							) {
+								p_r--;
+							}
+						}
+
+						// Remove spaces before number counting with possible '.' presence
+						if (_p >= r && *_p == '.' && (*(_p + 1) == ' ' || *(_p + 1) == '.') && (*(_p+2) == '-' || *(_p+2) == '+') ) {
+							if (*(_p + 1) == ' ') {
+								p_r--;
+							}
+							p_r--;
+						}
+
+						// Remove spaces after a opening bracket when followed by a number
+						if (_p >= r && *(_p+1) == '(' && *(_p+2) == ' ') {
+							p_r--;
+						}
+
+						// Remove spaces before number
+						if ( _p >= r && is_space_char(*(_p + 2))) {
+							// A point can be found prior to a number in case of query grouping
+							if ( _p >= r && ( *(_p+1) == '-' || *(_p+1) == '+' || *(_p+1) == '*' || *(_p+1) == '/' || *(_p+1) == '%' || *(_p+1) == ',' || *(_p+1) == '.')) {
+								p_r--;
+							}
+						}
+
+						replace_with_q_mark(
+							grouping_digest, grouping_lim, &grouping_count, &p_r, &grouping_limit_exceeded
+						);
+
+						if(len == i+1)
+						{
+							if(is_token_char(*s))
+								*p_r++ = *s;
+							i++;
+							continue;
+						}
+					} else {
+						// collapse any digits found in the string
+						if (replace_number) {
+							int str_len = p_r - p_r_t + 1;
+							int collapsed = 0;
+
+							for (int j = 0; j < str_len; j++) {
+								char* const c_p_r_t = ((char*)p_r_t + j);
+								char* const n_p_r_t = ((char*)p_r_t + j + 1);
+
+								if (is_digit_char(*c_p_r_t) && is_digit_char(*n_p_r_t)) {
+									memmove(c_p_r_t, c_p_r_t + 1, str_len - j);
+									collapsed += 1;
+								}
+							}
+
+							p_r -= collapsed;
+
+							int new_str_len = p_r - p_r_t + 1;
+							for (int j = 0; j < new_str_len; j++) {
+								char* const c_p_r_t = ((char*)p_r_t + j);
+								if (is_digit_char(*c_p_r_t)) {
+									*c_p_r_t = '?';
+								}
+							}
+						}
+					}
+
+					flag = 0;
+				}
+			}
+		}
+
+		// =================================================
+		// COPY CHAR
+		// =================================================
+		// convert every space char to ' '
+		if (*s == ')') {
+			if (grouping_digest > 0) {
+				grouping_digest -= 1;
+			};
+			grouping_count = 0;
+			grouping_limit_exceeded = 0;
+		}
+
+		if (lowercase==0) {
+			*p_r++ = !is_space_char(*s) ? *s : ' ';
+		} else {
+			*p_r++ = !is_space_char(*s) ? (tolower(*s)) : ' ';
+		}
+
+		if (*s == '(') {
+			grouping_digest += 1;
+			grouping_count = 0;
+			grouping_limit_exceeded = 0;
+		}
+
+		prev_char = *s++;
+
+		i++;
+	}
+
+	// remove a trailing space
+	if (p_r>r) {
+		char *e=p_r;
+		e--;
+		if (*e==' ') {
+			*e=0;
+			// maybe 2 trailing spaces . It happens with comments
+			e--;
+			if (*e==' ') {
+				*e=0;
+			}
+		}
+	}
+
+	*p_r = 0;
+
+	// process query stats
+	return r;
+}