MDEV-29853 Assertion `!strstr(table->name.m_name, "/FTS_") || purge_s…

…ys.must_wait_FTS()' failed in trx_t::commit

  - Failing debug assertion is to indicate whether the purge thread
is waiting when fts auxilary table is being dropped. But assertion
fails if the table name contains FTS_. So in fts_drop_table(), InnoDB
sets the auxilary table flag in transaction modified table list.

storage/innobase/dict/drop.cc

@@ -267,8 +267,7 @@ void trx_t::commit(std::vector<pfs_os_file_t> &deleted)
         if (btr_defragment_active)
           btr_defragment_remove_table(table);
         const fil_space_t *space= table->space;
-        ut_ad(!strstr(table->name.m_name, "/FTS_") ||
-              purge_sys.must_wait_FTS());
+        ut_ad(!p.second.is_aux_table() || purge_sys.must_wait_FTS());
         dict_sys.remove(table);
         if (const auto id= space ? space->id : 0)
         {

storage/innobase/fts/fts0fts.cc

@@ -1373,6 +1373,13 @@ static dberr_t fts_drop_table(trx_t *trx, const char *table_name, bool rename)
       return err;
     }
 
+#ifdef UNIV_DEBUG
+    for (auto &p : trx->mod_tables)
+    {
+      if (p.first == table)
+	p.second.set_aux_table();
+    }
+#endif /* UNIV_DEBUG */
     return DB_SUCCESS;
   }
 

storage/innobase/include/trx0trx.h

@@ -429,6 +429,10 @@ class trx_mod_table_time_t
   /** First modification of a system versioned column
   (NONE= no versioning, BULK= the table was dropped) */
   undo_no_t first_versioned= NONE;
+#ifdef UNIV_DEBUG
+  /** Whether the modified table is a FTS auxiliary table */
+  bool fts_aux_table= false;
+#endif /* UNIV_DEBUG */
 public:
   /** Constructor
   @param rows   number of modified rows so far */
@@ -483,6 +487,12 @@ class trx_mod_table_time_t
       first_versioned= NONE;
     return false;
   }
+
+#ifdef UNIV_DEBUG
+  void set_aux_table() { fts_aux_table= true; }
+
+  bool is_aux_table() const { return fts_aux_table; }
+#endif /* UNIV_DEBUG */
 };
 
 /** Collection of persistent tables and their first modification