MDEV-18310: Aria engine: Undo phase failed with "Got error 121 when

executing undo undo_key_delete" upon startup on datadir restored from
incremental backup

aria_log* files were not copied on --prepare --incremental-dir step from
incremental to destination backup directory.

extra/mariabackup/backup_copy.cc

@@ -1669,6 +1669,9 @@ ibx_copy_incremental_over_full()
 			}
 		}
 
+		if (!(ret = backup_files_from_datadir(xtrabackup_incremental_dir)))
+			goto cleanup;
+
 		/* copy buffer pool dump */
 		if (innobase_buffer_pool_filename) {
 			const char *src_name;
@@ -2180,20 +2183,26 @@ static bool backup_files_from_datadir(const char *dir_path)
 		if (info.type != OS_FILE_TYPE_FILE)
 			continue;
 
-		const char *pname = strrchr(info.name, IF_WIN('\\', '/'));
+		const char *pname = strrchr(info.name, OS_PATH_SEPARATOR);
 		if (!pname)
 			pname = info.name;
 
-		/* Copy aria log files, and aws keys for encryption plugins.*/
-		const char *prefixes[] = { "aria_log", "aws-kms-key" };
-		for (size_t i = 0; i < array_elements(prefixes); i++) {
-			if (starts_with(pname, prefixes[i])) {
-				ret = copy_file(ds_data, info.name, info.name, 1);
-				if (!ret) {
-					break;
-				}
-			}
-		}
+		if (!starts_with(pname, "aws-kms-key") &&
+			!starts_with(pname, "aria_log"))
+			/* For ES exchange the above line with the following code:
+			(!xtrabackup_prepare || !xtrabackup_incremental_dir ||
+				!starts_with(pname, "aria_log")))
+			*/
+			continue;
+
+		if (xtrabackup_prepare && xtrabackup_incremental_dir &&
+			file_exists(info.name))
+			unlink(info.name);
+
+		std::string full_path(dir_path);
+		full_path.append(1, OS_PATH_SEPARATOR).append(info.name);
+		if (!(ret = copy_file(ds_data, full_path.c_str() , info.name, 1)))
+			break;
 	}
 	os_file_closedir(dir);
 	return ret;

mysql-test/suite/mariabackup/incremental_backup.result

 call mtr.add_suppression("InnoDB: New log files created");
+CREATE TABLE t_aria(i INT) ENGINE ARIA;
 CREATE TABLE t(i INT PRIMARY KEY) ENGINE INNODB;
 BEGIN;
 INSERT INTO t VALUES(2);
@@ -11,11 +12,13 @@ INSERT INTO t VALUES(0);
 DELETE FROM t WHERE i=0;
 connection default;
 COMMIT;
+# Generate enough aria log records to increase area log file size
 SELECT * FROM t;
 i
 1
 2
 # Prepare full backup, apply incremental one
+# Aria log file was updated during applying incremental backup
 disconnect con1;
 # Restore and check results
 # shutdown server
@@ -27,3 +30,4 @@ i
 1
 2
 DROP TABLE t;
+DROP TABLE t_aria;

mysql-test/suite/mariabackup/incremental_backup.test

+--source include/have_aria.inc
 --source include/innodb_page_size.inc
 
 call mtr.add_suppression("InnoDB: New log files created");
 
-let $basedir=$MYSQLTEST_VARDIR/tmp/backup;
-let $incremental_dir=$MYSQLTEST_VARDIR/tmp/backup_inc1;
+let basedir=$MYSQLTEST_VARDIR/tmp/backup;
+let incremental_dir=$MYSQLTEST_VARDIR/tmp/backup_inc1;
 
+CREATE TABLE t_aria(i INT) ENGINE ARIA;
 CREATE TABLE t(i INT PRIMARY KEY) ENGINE INNODB;
 BEGIN;
 INSERT INTO t VALUES(2);
@@ -14,21 +16,73 @@ INSERT INTO t VALUES(1);
 
 echo # Create full backup , modify table, then create incremental/differential backup;
 --disable_result_log
-exec $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf  --backup --target-dir=$basedir;
+exec $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf  --backup --parallel=10 --target-dir=$basedir;
 --enable_result_log
 BEGIN;
 INSERT INTO t VALUES(0);
 DELETE FROM t WHERE i=0;
 connection default;
 COMMIT;
+
+--echo # Generate enough aria log records to increase area log file size
+--disable_query_log
+--disable_result_log
+INSERT INTO t_aria VALUES
+  (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
+  (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
+  (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
+  (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
+  (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
+  (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
+  (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
+  (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
+  (0), (1), (2), (3), (4), (5), (6), (7), (8), (9),
+  (0), (1), (2), (3), (4), (5), (6), (7), (8), (9);
+--let $i = 4
+while ($i) {
+INSERT INTO t_aria SELECT * FROM seq_1_to_2000;
+--dec $i
+}
+--enable_query_log
+--enable_result_log
+
 SELECT * FROM t;
-exec $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf  --backup --ftwrl-wait-timeout=5 --ftwrl-wait-threshold=300 --ftwrl-wait-query-type=all --target-dir=$incremental_dir --incremental-basedir=$basedir;
+# wf_incremental_init() allocates (page_size/4)*page_size bytes with mmap()
+# in each data file copy thread, what can fail on 32-bit platforms if threads
+# are too much, that's why don't set too big --parallel option value.
+exec $XTRABACKUP --defaults-file=$MYSQLTEST_VARDIR/my.cnf --backup --parallel=2 --ftwrl-wait-timeout=5 --ftwrl-wait-threshold=300 --ftwrl-wait-query-type=all --target-dir=$incremental_dir --incremental-basedir=$basedir;
 
 --disable_result_log
 echo # Prepare full backup, apply incremental one;
 exec $XTRABACKUP --prepare --target-dir=$basedir;
 exec $XTRABACKUP --prepare --target-dir=$basedir --incremental-dir=$incremental_dir ;
 
+let perl_result_file=$MYSQLTEST_VARDIR/tmp/check_file_size_result.inc;
+
+--perl END_OF_FILE
+  use strict;
+  use warnings;
+
+  my $dst_file = "$ENV{'basedir'}/aria_log.00000001";
+  my $src_file = "$ENV{'incremental_dir'}/aria_log.00000001";
+  my $out_file = $ENV{'perl_result_file'};
+
+  my $dst_size = -s $dst_file;
+  my $src_size = -s $src_file;
+
+  open (my $output, '>', $out_file) or die $!;
+  if ($dst_size >= $src_size) {
+    print $output '--echo # Aria log file was updated during applying incremental backup'."\n";
+  }
+  else {
+    print $output '--echo #  Aria log file was NOT updated during applying incremental backup'."\n";
+  }
+  close $output;
+END_OF_FILE
+
+--source $perl_result_file
+--remove_file $perl_result_file
+
 disconnect con1;
 echo # Restore and check results;
 let $targetdir=$basedir;
@@ -37,6 +91,7 @@ let $targetdir=$basedir;
 
 SELECT * FROM t;
 DROP TABLE t;
+DROP TABLE t_aria;
 
 # Cleanup
 rmdir $basedir;