Merge revert of BUG#31360522 from 'mysql-5.7' into mysql-8.0

Change-Id: Ib7914c4c0bc399a7a7ff0bcca3db3271cc491db2

Author: karthik-kamath

sql/sql_partition.cc

@@ -770,11 +770,6 @@ static bool handle_list_of_fields(List_iterator<char> it, TABLE *table,
       */
       for (i = 0; i < num_key_parts; i++) {
         Field *field = table->key_info[primary_key].key_part[i].field;
-        // BLOB/TEXT columns are not allowed in partitioning keys.
-        if (field->is_flag_set(BLOB_FLAG)) {
-          my_error(ER_BLOB_FIELD_IN_PART_FUNC_ERROR, MYF(0));
-          return true;
-        }
         field->set_flag(GET_FIXED_FIELDS_FLAG);
       }
     } else {

sql/table.cc

@@ -2822,15 +2822,8 @@ bool create_key_part_field_with_prefix_length(TABLE *table, MEM_ROOT *root) {
          key_part < key_part_end; key_part++) {
       Field *field = key_part->field = table->field[key_part->fieldnr - 1];
 
-      /*
-        For spatial indexes, the key parts are assigned the length (4 *
-        sizeof(double)) in prepare_key_column() and the field->key_length() is
-        set to 0. This makes it appear like a prefixed index. However, prefixed
-        indexes are not allowed on Geometric columns. Hence skipping new field
-        creation for Geometric columns.
-      */
       if (field->key_length() != key_part->length &&
-          field->type() != MYSQL_TYPE_GEOMETRY) {
+          !field->is_flag_set(BLOB_FLAG)) {
         /*
           We are using only a prefix of the column as a key:
           Create a new field for the key part that matches the index