Improve diagnostics in order to catch MDEV-18868 and similar bugs

storage/innobase/fts/fts0fts.cc

@@ -2546,7 +2546,8 @@ fts_get_max_cache_size(
 		}
 	} else {
 		ib::error() << "(" << error << ") reading max"
-			" cache config value from config table";
+			" cache config value from config table "
+			<< fts_table->table->name;
 	}
 
 	ut_free(value.f_str);
@@ -2719,7 +2720,8 @@ fts_cmp_set_sync_doc_id(
 	} else {
 		*doc_id = 0;
 
-		ib::error() << "(" << error << ") while getting next doc id.";
+		ib::error() << "(" << error << ") while getting next doc id "
+			"for table " << table->name;
 		fts_sql_rollback(trx);
 
 		if (error == DB_DEADLOCK) {
@@ -2799,7 +2801,8 @@ fts_update_sync_doc_id(
 			cache->synced_doc_id = doc_id;
 		} else {
 			ib::error() << "(" << error << ") while"
-				" updating last doc id.";
+				" updating last doc id for table"
+				<< table->name;
 
 			fts_sql_rollback(trx);
 		}
@@ -4044,7 +4047,8 @@ fts_sync_write_words(
 
 		if (UNIV_UNLIKELY(error != DB_SUCCESS) && !print_error) {
 			ib::error() << "(" << error << ") writing"
-				" word node to FTS auxiliary index table.";
+				" word node to FTS auxiliary index table "
+				<< table->name;
 			print_error = TRUE;
 		}
 	}
@@ -4199,7 +4203,8 @@ fts_sync_commit(
 		fts_sql_commit(trx);
 	} else {
 		fts_sql_rollback(trx);
-		ib::error() << "(" << error << ") during SYNC.";
+		ib::error() << "(" << error << ") during SYNC of "
+			"table " << sync->table->name;
 	}
 
 	if (UNIV_UNLIKELY(fts_enable_diag_print) && elapsed_time) {
@@ -4970,7 +4975,8 @@ fts_get_rows_count(
 				trx->error_state = DB_SUCCESS;
 			} else {
 				ib::error() << "(" << error
-					<< ") while reading FTS table.";
+					<< ") while reading FTS table "
+					<< table_name;
 
 				break;			/* Exit the loop. */
 			}

storage/innobase/include/btr0bulk.h

@@ -326,6 +326,8 @@ class BtrBulk
 	/** Re-latch all latches */
 	void latch();
 
+	dict_index_t* index() { return m_index; }
+
 private:
 	/** Insert a tuple to a page in a level
 	@param[in]	tuple	tuple to insert

storage/innobase/row/row0ftsort.cc

@@ -924,7 +924,7 @@ fts_parallel_tokenization(
 				<< " records, the sort queue has "
 				<< UT_LIST_GET_LEN(psort_info->fts_doc_list)
 				<< " records. But sort cannot get the next"
-				" records";
+				" records during alter table " << table->name;
 			goto exit;
 		}
 	} else if (psort_info->state == FTS_PARENT_EXITING) {
@@ -1220,7 +1220,9 @@ row_merge_write_fts_word(
 
 		if (UNIV_UNLIKELY(error != DB_SUCCESS)) {
 			ib::error() << "Failed to write word to FTS auxiliary"
-				" index table, error " << error;
+				" index table "
+				<< ins_ctx->btr_bulk->index()->table->name
+				<< ", error " << error;
 			ret = error;
 		}