Check consistency between frm and MyRocks data dictionary at startup about mysql-5.6

[hermanlee]

Comment by jkedgar
Thursday Sep 10, 2015 at 18:55 GMT

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I have this working to check the number of keys in the table. I thought about attempting to compare the table names, but wondered if that would run into problems when aliases were used. What other information do we store in the MyRocks data dictionary that you would like to see compared?

[hermanlee]

Comment by yoshinorim
Thursday Sep 10, 2015 at 22:21 GMT

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We store database_name.table_name in MyRocks data dictionary idx_id=0x1 (https://github.com/MySQLOnRocksDB/mysql-5.6/wiki/MyRocks-data-dictionary-format). We don't store aliases in MyRocks data dictionary.

[hermanlee]

Comment by jkedgar
Thursday Sep 10, 2015 at 22:23 GMT

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Okay. I'll look into the table name further. Besides these two things, what should we check the consistency of?

[hermanlee]

Comment by yoshinorim
Thursday Sep 17, 2015 at 00:52 GMT

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Sorry I missed the last comment. I think checking database_name.table_name for all tables is fine. Checking indexes will need to parse frm file itself, which will make things more complex.

[hermanlee]

Is failing the system when there are tables with .frm files but not using the rocksdb storage engine too restrictive? It seems like there could be generic uses cases for creating tables with other storage engines.

[yoshinorim]

As far as it's configurable, I think failing the system at startup is ok. Creating tables with other storage engines may happen on temporary tables, but tmp tables can easily be filtered out.

[hermanlee]

There are also tables created using the blackhole engine though that persist across restarts. The current checks would always fail for them.

[jkedgar]

Fixed: https://reviews.facebook.net/D47619