MDEV-19241 InnoDB fails to write MLOG_INDEX_LOAD upon completing ALTER TABLE

Similar to what was done in commit aa3f7a10
for FULLTEXT INDEX, we must ensure that MLOG_INDEX_LOAD records will always
be written if redo logging was disabled.

row_merge_build_indexes(): Invoke row_merge_write_redo() also when
online operation is not being executed or an error occurs.
In case of an error, invoke flush_observer->interrupted() so that
the pages will not be flushed but merely evicted from the buffer pool.
Before resuming redo logging, it is crucial for the correctness of
mariabackup and InnoDB crash recovery to flush or evict all affected pages
and to write MLOG_INDEX_LOAD records.

mysql-test/suite/innodb/r/log_alter_table.result

@@ -7,11 +7,11 @@
 #
 CREATE TABLE t1 (a INT NOT NULL, b INT UNIQUE) ENGINE=InnoDB;
 INSERT INTO t1 VALUES (1,2);
-ALTER TABLE t1 ADD PRIMARY KEY(a), ALGORITHM=INPLACE;
-ALTER TABLE t1 DROP INDEX b, ADD INDEX (b);
+ALTER TABLE t1 ADD PRIMARY KEY(a), LOCK=SHARED, ALGORITHM=INPLACE;
+ALTER TABLE t1 DROP INDEX b, ADD INDEX (b), LOCK=SHARED;
 # Kill the server
-FOUND 1 /scan .*: multi-log rec MLOG_FILE_CREATE2.*page .*:0/ in mysqld.1.err
-FOUND 1 /scan .*: log rec MLOG_INDEX_LOAD/ in mysqld.1.err
+FOUND 2 /scan \d+: multi-log rec MLOG_FILE_CREATE2 len \d+ page \d+:0/ in mysqld.1.err
+FOUND 3 /scan \d+: log rec MLOG_INDEX_LOAD/ in mysqld.1.err
 CHECK TABLE t1;
 Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK

mysql-test/suite/innodb/t/log_alter_table.test

@@ -19,9 +19,9 @@ CREATE TABLE t1 (a INT NOT NULL, b INT UNIQUE) ENGINE=InnoDB;
 # MLOG_INDEX_LOAD will not be emitted for empty tables. Insert a row.
 INSERT INTO t1 VALUES (1,2);
 # We should get two MLOG_INDEX_LOAD for this.
-ALTER TABLE t1 ADD PRIMARY KEY(a), ALGORITHM=INPLACE;
+ALTER TABLE t1 ADD PRIMARY KEY(a), LOCK=SHARED, ALGORITHM=INPLACE;
 # And one MLOG_INDEX_LOAD for this.
-ALTER TABLE t1 DROP INDEX b, ADD INDEX (b);
+ALTER TABLE t1 DROP INDEX b, ADD INDEX (b), LOCK=SHARED;
 
 --let CLEANUP_IF_CHECKPOINT=DROP TABLE t1;
 --source include/no_checkpoint_end.inc
@@ -32,10 +32,10 @@ ALTER TABLE t1 DROP INDEX b, ADD INDEX (b);
 let SEARCH_FILE = $MYSQLTEST_VARDIR/log/mysqld.1.err;
 let SEARCH_ABORT=NOT FOUND;
 # ensure that we have exactly 2 records there.
-let SEARCH_PATTERN=scan .*: multi-log rec MLOG_FILE_CREATE2.*page .*:0;
+let SEARCH_PATTERN=scan \d+: multi-log rec MLOG_FILE_CREATE2 len \d+ page \d+:0;
 --source include/search_pattern_in_file.inc
 # ensure that we have exactly 3 records there.
-let SEARCH_PATTERN=scan .*: log rec MLOG_INDEX_LOAD;
+let SEARCH_PATTERN=scan \d+: log rec MLOG_INDEX_LOAD;
 --source include/search_pattern_in_file.inc
 
 CHECK TABLE t1;

storage/innobase/row/row0merge.cc

@@ -4893,23 +4893,28 @@ row_merge_build_indexes(
 		if (indexes[i]->type & DICT_FTS) {
 			row_fts_psort_info_destroy(psort_info, merge_info);
 			fts_psort_initiated = false;
-		} else if (error != DB_SUCCESS || !online) {
-			/* Do not apply any online log. */
+		} else if (dict_index_is_spatial(indexes[i])) {
+			/* We never disable redo logging for
+			creating SPATIAL INDEX. Avoid writing any
+			unnecessary MLOG_INDEX_LOAD record. */
 		} else if (old_table != new_table) {
 			ut_ad(!sort_idx->online_log);
 			ut_ad(sort_idx->online_status
 			      == ONLINE_INDEX_COMPLETE);
-		} else {
-			if (dict_index_is_spatial(indexes[i])) {
-				/* We never disable redo logging for
-				creating SPATIAL INDEX. Avoid writing any
-				unnecessary MLOG_INDEX_LOAD record. */
-			} else if (FlushObserver* flush_observer =
-					trx->get_flush_observer()) {
-				flush_observer->flush();
-				row_merge_write_redo(indexes[i]);
+		} else if (FlushObserver* flush_observer =
+			   trx->get_flush_observer()) {
+			if (error != DB_SUCCESS) {
+				flush_observer->interrupted();
 			}
+			flush_observer->flush();
+			row_merge_write_redo(indexes[i]);
+		}
 
+		if (old_table != new_table
+		    || (indexes[i]->type & (DICT_FTS | DICT_SPATIAL))
+		    || error != DB_SUCCESS || !online) {
+			/* Do not apply any online log. */
+		} else {
 			if (global_system_variables.log_warnings > 2) {
 				sql_print_information(
 					"InnoDB: Online DDL : Applying"
@@ -5016,13 +5021,7 @@ row_merge_build_indexes(
 
 		flush_observer->flush();
 
-		trx->remove_flush_observer();
-
-		if (trx_is_interrupted(trx)) {
-			error = DB_INTERRUPTED;
-		}
-
-		if (error == DB_SUCCESS && old_table != new_table) {
+		if (old_table != new_table) {
 			for (const dict_index_t* index
 				     = dict_table_get_first_index(new_table);
 			     index != NULL;
@@ -5033,6 +5032,12 @@ row_merge_build_indexes(
 				}
 			}
 		}
+
+		trx->remove_flush_observer();
+
+		if (trx_is_interrupted(trx)) {
+			error = DB_INTERRUPTED;
+		}
 	}
 
 	DBUG_RETURN(error);