MDEV-27591 Connect tables (FIX/DOS) don't work with DESC keys - wrong results

disallow descending indexes in connect

storage/connect/ha_connect.cc

@@ -1812,6 +1812,12 @@ PIXDEF ha_connect::GetIndexInfo(TABLE_SHARE *s)
       pn= (char*)kp.key_part[k].field->field_name.str;
       name= PlugDup(g, pn);
 
+      if (kp.key_part[k].key_part_flag & HA_REVERSE_SORT)
+      {
+        strcpy(g->Message, "Descending indexes are not supported");
+        xdp->Invalid= true;
+      }
+
       // Allocate the key part description block
       kpp= new(g) KPARTDEF(name, k + 1);
       kpp->SetKlen(kp.key_part[k].length);
@@ -6944,6 +6950,9 @@ int ha_connect::create(const char *name, TABLE *table_arg,
         strcpy(g->Message, "Compressed tables are not indexable");
         my_message(ER_UNKNOWN_ERROR, g->Message, MYF(0));
         rc= HA_ERR_UNSUPPORTED;
+      } else if (xdp->Invalid) {
+        my_message(ER_UNKNOWN_ERROR, g->Message, MYF(0));
+        rc= HA_ERR_UNSUPPORTED;
       } else if (GetIndexType(type) == 1) {
         PDBUSER dup= PlgGetUser(g);
         PCATLG  cat= (dup) ? dup->Catalog : NULL;

storage/connect/mysql-test/connect/r/index.result

@@ -139,3 +139,12 @@ DELETE FROM t1;
 DROP TABLE t1;
 DROP TABLE t2;
 DROP TABLE t3;
+#
+# MDEV-27591 Connect tables (FIX/DOS) don't work with DESC keys - wrong results
+#
+CREATE TABLE t1 (
+id INT,
+f VARCHAR(32),
+PRIMARY KEY (id DESC)
+) ENGINE=CONNECT TABLE_TYPE=DOS FILE_NAME='emp.txt';
+ERROR HY000: Descending indexes are not supported

storage/connect/mysql-test/connect/t/index.test

@@ -78,6 +78,16 @@ DROP TABLE t1;
 DROP TABLE t2;
 DROP TABLE t3;
 
+--echo #
+--echo # MDEV-27591 Connect tables (FIX/DOS) don't work with DESC keys - wrong results
+--echo #
+--error ER_UNKNOWN_ERROR
+CREATE TABLE t1 (
+  id INT,
+  f VARCHAR(32),
+  PRIMARY KEY (id DESC)
+) ENGINE=CONNECT TABLE_TYPE=DOS FILE_NAME='emp.txt';
+
 #
 # Clean up
 #