row0vers.c:

  Add diagnostic code to track a probable table corruption reported by a user

innobase/row/row0vers.c

@@ -58,6 +58,7 @@ row_vers_impl_x_locked_off_kernel(
 	ibool		rec_del;
 	ulint		err;
 	mtr_t		mtr;
+	char            err_buf[1000];
 	
 	ut_ad(mutex_own(&kernel_mutex));
 	ut_ad(!rw_lock_own(&(purge_sys->latch), RW_LOCK_SHARED));
@@ -74,7 +75,26 @@ row_vers_impl_x_locked_off_kernel(
 
 	clust_rec = row_get_clust_rec(BTR_SEARCH_LEAF, rec, index,
 							&clust_index, &mtr);
-	ut_a(clust_rec);
+	if (!clust_rec) {
+	        rec_sprintf(err_buf, 900, rec);
+
+	        ut_print_timestamp(stderr);
+	        fprintf(stderr,
+"  InnoDB: Error: cannot find the clustered index record\n"
+"InnoDB: for a secondary index record in table %s index %s.\n"
+"InnoDB: Secondary index record %s.\n"
+"InnoDB: The table is probably corrupt. Please run CHECK TABLE on it.\n"
+"InnoDB: You can try to repair the table by dump + drop + reimport.\n"
+"InnoDB: Send a detailed bug report to mysql@lists.mysql.com.\n",
+		  index->table_name, index->name, err_buf);
+	        mutex_enter(&kernel_mutex);
+	        mtr_commit(&mtr);
+
+	        /* We assume there is no lock on the record, though this
+	        is not certain because the table is apparently corrupt */
+
+	        return(NULL);
+	}
 
 	trx_id = row_get_rec_trx_id(clust_rec, clust_index);