MDEV-23162 Improve Protocol performance for numeric data

Avoid character set conversion for numeric data in this scenario:

SET NAMES utf8;
CREATE OR REPLACE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1);
SELECT a FROM t1;

1 files changed, 18 insertions, 9 deletions

diff --git a/sql/protocol.cc b/sql/protocol.cc
index 07d09ecb4ee..a97e0d0997d 100644
--- a/sql/protocol.cc
+++ b/sql/protocol.cc
@@ -853,7 +853,7 @@ bool Protocol_text::store_field_metadata(const THD * thd,
   if (thd->client_capabilities & CLIENT_PROTOCOL_41)
   {
     const LEX_CSTRING def= {STRING_WITH_LEN("def")};
-    if (store_ident(def) ||
+    if (store_ident(def, MY_REPERTOIRE_ASCII) ||
         store_ident(field.db_name) ||
         store_ident(field.table_name) ||
         store_ident(field.org_table_name) ||
@@ -868,7 +868,8 @@ bool Protocol_text::store_field_metadata(const THD * thd,
         Don't apply character set conversion:
         extended metadata is a binary encoded data.
       */
-      if (store_lex_cstring(metadata.lex_cstring(), cs, &my_charset_bin))
+      if (store_lex_cstring(metadata.lex_cstring(), cs,
+                            MY_REPERTOIRE_UNICODE30, &my_charset_bin))
         return true;
     }
     if (packet->realloc(packet->length() + 12))
@@ -1182,10 +1183,12 @@ bool Protocol_text::store_null()
 */
 
 bool Protocol::store_string_aux(const char *from, size_t length,
-                                CHARSET_INFO *fromcs, CHARSET_INFO *tocs)
+                                CHARSET_INFO *fromcs,
+                                my_repertoire_t from_repertoire,
+                                CHARSET_INFO *tocs)
 {
   /* 'tocs' is set 0 when client issues SET character_set_results=NULL */
-  if (needs_conversion(fromcs, tocs))
+  if (needs_conversion(fromcs, from_repertoire, tocs))
   {
     /* Store with conversion */
     return net_store_data_cs((uchar*) from, length, fromcs, tocs);
@@ -1208,7 +1211,9 @@ bool Protocol::store_warning(const char *from, size_t length)
 
 
 bool Protocol_text::store_str(const char *from, size_t length,
-                              CHARSET_INFO *fromcs, CHARSET_INFO *tocs)
+                              CHARSET_INFO *fromcs,
+                              my_repertoire_t from_repertoire,
+                              CHARSET_INFO *tocs)
 {
 #ifndef DBUG_OFF
   DBUG_PRINT("info", ("Protocol_text::store field %u (%u): %.*b", field_pos,
@@ -1217,7 +1222,7 @@ bool Protocol_text::store_str(const char *from, size_t length,
   DBUG_ASSERT(valid_handler(field_pos, PROTOCOL_SEND_STRING));
   field_pos++;
 #endif
-  return store_string_aux(from, length, fromcs, tocs);
+  return store_string_aux(from, length, fromcs, from_repertoire, tocs);
 }
 
 
@@ -1330,7 +1335,8 @@ bool Protocol_text::store(Field *field)
     dbug_tmp_restore_column_map(table->read_set, old_map);
 #endif
 
-  return store_string_aux(str.ptr(), str.length(), str.charset(), tocs);
+  return store_string_aux(str.ptr(), str.length(), str.charset(),
+                          field->dtcollation().repertoire, tocs);
 }
 
 
@@ -1449,10 +1455,12 @@ void Protocol_binary::prepare_for_resend()
 
 
 bool Protocol_binary::store_str(const char *from, size_t length,
-                                CHARSET_INFO *fromcs, CHARSET_INFO *tocs)
+                                CHARSET_INFO *fromcs,
+                                my_repertoire_t from_repertoire,
+                                CHARSET_INFO *tocs)
 {
   field_pos++;
-  return store_string_aux(from, length, fromcs, tocs);
+  return store_string_aux(from, length, fromcs, from_repertoire, tocs);
 }
 
 bool Protocol_binary::store_null()
@@ -1515,6 +1523,7 @@ bool Protocol_binary::store_decimal(const my_decimal *d)
   StringBuffer<DECIMAL_MAX_STR_LENGTH> str;
   (void) d->to_string(&str);
   return store_str(str.ptr(), str.length(), str.charset(),
+                   MY_REPERTOIRE_ASCII,
                    thd->variables.character_set_results);
 }