fix myrocks_hotbackup for python3

[i18nsite]

see https://peps.python.org/pep-0469/

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[grooverdan]

Thanks for the contribution.

Can you rebase this to 10.5.

Also first commit should be titled more like the pr - 'fix myrocksdb_hostbackup for python3`. Can you also mention the python version it is now finally failing with.

Can the commit be squashed up too. Micro changes aren't adding value to the commit history.

[grooverdan]

Can you describe the significance of this? It looks like a backwards/forwards utf8 coding/decoding.

[i18nsite]

In python3, I don't know why, db and filename is bytes , not str.

After I modified it like this, it can run.Otherwise, an error will be reported.

[i18nsite]

see this https://github.com/oppia/oppia/wiki/Bytes-and-string-handling-in-Python-3

[i18nsite]

By the way, I have a question.

I use this can recover data , but failed on MariaDB 11.5.2 boot

recover cmd

DATADIR=/mnt/data/i18n/mariadb/data
systemctl stop mariadb
/usr/bin/python3 /usr/local/mysql/bin/myrocks_hotbackup --move_back \
--datadir=$DATADIR --rocksdb_datadir=$DATADIR \
--rocksdb_waldir=$DATADIR --backup_dir=/tmp/myrocks.bak
chown -R mysql:mysql $DATADIR
systemctl start mariadb

failed log

2024-11-13 12:53:00 0 [Warning] RocksDB: Schema mismatch - A .frm file exists for table i18n.authUidMail, but that table is not registered in RocksDB
2024-11-13 12:53:00 0 [Warning] RocksDB: Schema mismatch - A .frm file exists for table i18n.authUa, but that table is not registered in RocksDB
2024-11-13 12:53:00 0 [Warning] RocksDB: Schema mismatch - A .frm file exists for table i18n.authHardware, but that table is not registered in RocksDB
2024-11-13 12:53:00 0 [Warning] RocksDB: Schema mismatch - A .frm file exists for table i18n.uidHost, but that table is not registered in RocksDB
2024-11-13 12:53:00 0 [ERROR] RocksDB: Problems validating data dictionary against .frm files, exiting
2024-11-13 12:53:00 0 [ERROR] RocksDB: Failed to initialize DDL manager.
2024-11-13 12:53:00 0 [ERROR] Plugin 'ROCKSDB' registration as a STORAGE ENGINE failed.
2024-11-13 12:53:00 0 [Note] Plugin 'InnoDB' is disabled.
2024-11-13 12:53:00 0 [Note] Plugin 'FEEDBACK' is disabled.
2024-11-13 12:53:00 0 [Note] Plugin 'wsrep-provider' is disabled.
2024-11-13 12:53:00 0 [Note] Semi-sync replication enabled on the master.
2024-11-13 12:53:00 0 [ERROR] Unknown/unsupported storage engine: rocksdb
2024-11-13 12:53:00 0 [ERROR] Aborting

ls dir

❯ ls /mnt/data/i18n/mariadb/data
#rocksdb    000265.sst  000269.sst  000272.sst         aria_log_control  i18n             mariadb_upgrade_info  OPTIONS-000251      sys
000261.sst  000267.sst  000271.sst  aria_log.00000001  CURRENT           MANIFEST-000244  mysql                 performance_schema
/tmp/myrocks.bak                                                                                                                         

[i18nsite]

I originally wanted to use mariadb-backup to back up myrocks, but found that it was impossible to back up myrocks without InnoDB.

For details, see:
https://lists.mariadb.org/hyperkitty/list/[email protected]/thread/7Z64ZTVLUESRSTU5QIED4OLNOCMT5DON/

I tried to use myrocks_hotbackup to backup and restore, but got stuck again. A .frm file exists for table i18n.uidHost, but that table is not registered in RocksDB

this is frustrating

[i18nsite]

fixed , I use charset='utf8' for mysql connection , fix is return bytes in python3